diff --git a/src/bindgen/ir/enumeration.rs b/src/bindgen/ir/enumeration.rs
index f0af34bcc..aa83a7802 100644
--- a/src/bindgen/ir/enumeration.rs
+++ b/src/bindgen/ir/enumeration.rs
@@ -680,15 +680,20 @@ impl Enum {
                     }
                     write!(out, " {tag_name}");
 
-                    if config.cpp_compatible_c() {
-                        out.new_line();
-                        out.write("#ifdef __cplusplus");
-                        out.new_line();
-                        write!(out, "  : {prim}");
-                        out.new_line();
-                        out.write("#endif // __cplusplus");
-                        out.new_line();
-                    }
+                    // Emit typed enum syntax (valid in C23 or later or C++)
+                    let cond = if config.cpp_compatible_c() {
+                        "defined(__cplusplus) || __STDC_VERSION__ >= 202311L"
+                    } else {
+                        "__STDC_VERSION__ >= 202311L"
+                    };
+
+                    out.new_line();
+                    write!(out, "#if {cond}");
+                    out.new_line();
+                    write!(out, "  : {prim}");
+                    out.new_line();
+                    write!(out, "#endif // {cond}");
+                    out.new_line();
                 } else {
                     if config.style.generate_typedef() {
                         out.write("typedef ");
@@ -759,8 +764,8 @@ impl Enum {
         }
 
         // Emit typedef specifying the tag enum's size if necessary.
-        // In C++ enums can "inherit" from numeric types (`enum E: uint8_t { ... }`),
-        // but in C `typedef uint8_t E` is the only way to give a fixed size to `E`.
+        // In C++ or C23 enums can "inherit" from numeric types (`enum E: uint8_t { ... }`),
+        // but in older versions of C `typedef uint8_t E` is the only way to give a fixed size to `E`.
         if let Some(prim) = size {
             if config.cpp_compatible_c() {
                 out.new_line_if_not_start();
@@ -768,8 +773,30 @@ impl Enum {
             }
 
             if config.language != Language::Cxx {
+                if config.language == Language::C {
+                    out.new_line();
+                    out.write("#if __STDC_VERSION__ >= 202311L");
+
+                    out.new_line();
+                    write!(
+                        out,
+                        "{} enum {} {};",
+                        config.language.typedef(),
+                        tag_name,
+                        tag_name
+                    );
+
+                    out.new_line();
+                    out.write("#else");
+                }
+
                 out.new_line();
                 write!(out, "{} {} {};", config.language.typedef(), prim, tag_name);
+
+                if config.language == Language::C {
+                    out.new_line();
+                    out.write("#endif // __STDC_VERSION__ >= 202311L");
+                }
             }
 
             if config.cpp_compatible_c() {
diff --git a/tests/expectations/alias.c b/tests/expectations/alias.c
index 90478299a..31a559001 100644
--- a/tests/expectations/alias.c
+++ b/tests/expectations/alias.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Status {
+enum Status
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Ok,
   Err,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   int32_t a;
diff --git a/tests/expectations/alias.compat.c b/tests/expectations/alias.compat.c
index 565fb53fe..7b65350ef 100644
--- a/tests/expectations/alias.compat.c
+++ b/tests/expectations/alias.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Status
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Ok,
   Err,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/alias_both.c b/tests/expectations/alias_both.c
index 1c537b5d9..ac4ae5953 100644
--- a/tests/expectations/alias_both.c
+++ b/tests/expectations/alias_both.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Status {
+enum Status
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Ok,
   Err,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Dep {
   int32_t a;
diff --git a/tests/expectations/alias_both.compat.c b/tests/expectations/alias_both.compat.c
index a48b899ed..9115d550e 100644
--- a/tests/expectations/alias_both.compat.c
+++ b/tests/expectations/alias_both.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Status
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Ok,
   Err,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Dep {
diff --git a/tests/expectations/alias_tag.c b/tests/expectations/alias_tag.c
index 82f12dd52..e3360f2c8 100644
--- a/tests/expectations/alias_tag.c
+++ b/tests/expectations/alias_tag.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Status {
+enum Status
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Ok,
   Err,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Dep {
   int32_t a;
diff --git a/tests/expectations/alias_tag.compat.c b/tests/expectations/alias_tag.compat.c
index 9f04708cf..180777a05 100644
--- a/tests/expectations/alias_tag.compat.c
+++ b/tests/expectations/alias_tag.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Status
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Ok,
   Err,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Status Status;
+#else
 typedef uint32_t Status;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Dep {
diff --git a/tests/expectations/annotation.c b/tests/expectations/annotation.c
index 9d72830a6..538014d4d 100644
--- a/tests/expectations/annotation.c
+++ b/tests/expectations/annotation.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   int32_t m0;
@@ -18,12 +26,20 @@ typedef struct {
   float y;
 } B;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   F_Tag tag;
@@ -40,12 +56,20 @@ typedef union {
   Bar_Body bar;
 } F;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;
diff --git a/tests/expectations/annotation.compat.c b/tests/expectations/annotation.compat.c
index 4a90fcabc..be3372cc7 100644
--- a/tests/expectations/annotation.compat.c
+++ b/tests/expectations/annotation.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -25,16 +29,20 @@ typedef struct {
 } B;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -53,16 +61,20 @@ typedef union {
 } F;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/annotation_both.c b/tests/expectations/annotation_both.c
index 17c4fd7bc..f9117a091 100644
--- a/tests/expectations/annotation_both.c
+++ b/tests/expectations/annotation_both.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct A {
   int32_t m0;
@@ -18,12 +26,20 @@ typedef struct B {
   float y;
 } B;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Bar_Body {
   F_Tag tag;
@@ -40,12 +56,20 @@ typedef union F {
   Bar_Body bar;
 } F;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct There_Body {
   uint8_t x;
diff --git a/tests/expectations/annotation_both.compat.c b/tests/expectations/annotation_both.compat.c
index 57d9f297e..bb52eec34 100644
--- a/tests/expectations/annotation_both.compat.c
+++ b/tests/expectations/annotation_both.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct A {
@@ -25,16 +29,20 @@ typedef struct B {
 } B;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Bar_Body {
@@ -53,16 +61,20 @@ typedef union F {
 } F;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct There_Body {
diff --git a/tests/expectations/annotation_tag.c b/tests/expectations/annotation_tag.c
index 826c41ab7..86a105a58 100644
--- a/tests/expectations/annotation_tag.c
+++ b/tests/expectations/annotation_tag.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct A {
   int32_t m0;
@@ -18,12 +26,20 @@ struct B {
   float y;
 };
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Bar_Body {
   F_Tag tag;
@@ -40,12 +56,20 @@ union F {
   struct Bar_Body bar;
 };
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct There_Body {
   uint8_t x;
diff --git a/tests/expectations/annotation_tag.compat.c b/tests/expectations/annotation_tag.compat.c
index ab022610c..37db89b9f 100644
--- a/tests/expectations/annotation_tag.compat.c
+++ b/tests/expectations/annotation_tag.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct A {
@@ -25,16 +29,20 @@ struct B {
 };
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Bar_Body {
@@ -53,16 +61,20 @@ union F {
 };
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct There_Body {
diff --git a/tests/expectations/asserted_cast.c b/tests/expectations/asserted_cast.c
index 5dad52255..c8bb3f99d 100644
--- a/tests/expectations/asserted_cast.c
+++ b/tests/expectations/asserted_cast.c
@@ -9,12 +9,20 @@
 
 typedef struct I I;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   H_Foo,
   H_Bar,
   H_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;
@@ -31,12 +39,20 @@ typedef struct {
   };
 } H;
 
-enum J_Tag {
+enum J_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   J_Foo,
   J_Bar,
   J_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum J_Tag J_Tag;
+#else
 typedef uint8_t J_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;
@@ -53,12 +69,20 @@ typedef struct {
   };
 } J;
 
-enum K_Tag {
+enum K_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   K_Foo,
   K_Bar,
   K_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum K_Tag K_Tag;
+#else
 typedef uint8_t K_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   K_Tag tag;
diff --git a/tests/expectations/asserted_cast.compat.c b/tests/expectations/asserted_cast.compat.c
index 2d75731f0..58b0a2aa3 100644
--- a/tests/expectations/asserted_cast.compat.c
+++ b/tests/expectations/asserted_cast.compat.c
@@ -10,16 +10,20 @@
 typedef struct I I;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   H_Foo,
   H_Bar,
   H_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -38,16 +42,20 @@ typedef struct {
 } H;
 
 enum J_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   J_Foo,
   J_Bar,
   J_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum J_Tag J_Tag;
+#else
 typedef uint8_t J_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -66,16 +74,20 @@ typedef struct {
 } J;
 
 enum K_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   K_Foo,
   K_Bar,
   K_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum K_Tag K_Tag;
+#else
 typedef uint8_t K_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/asserted_cast_both.c b/tests/expectations/asserted_cast_both.c
index 1cb6854a2..a87e72e45 100644
--- a/tests/expectations/asserted_cast_both.c
+++ b/tests/expectations/asserted_cast_both.c
@@ -9,12 +9,20 @@
 
 typedef struct I I;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   H_Foo,
   H_Bar,
   H_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct H_Bar_Body {
   uint8_t x;
@@ -31,12 +39,20 @@ typedef struct H {
   };
 } H;
 
-enum J_Tag {
+enum J_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   J_Foo,
   J_Bar,
   J_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum J_Tag J_Tag;
+#else
 typedef uint8_t J_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct J_Bar_Body {
   uint8_t x;
@@ -53,12 +69,20 @@ typedef struct J {
   };
 } J;
 
-enum K_Tag {
+enum K_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   K_Foo,
   K_Bar,
   K_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum K_Tag K_Tag;
+#else
 typedef uint8_t K_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct K_Bar_Body {
   K_Tag tag;
diff --git a/tests/expectations/asserted_cast_both.compat.c b/tests/expectations/asserted_cast_both.compat.c
index 815190b51..104995c44 100644
--- a/tests/expectations/asserted_cast_both.compat.c
+++ b/tests/expectations/asserted_cast_both.compat.c
@@ -10,16 +10,20 @@
 typedef struct I I;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   H_Foo,
   H_Bar,
   H_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct H_Bar_Body {
@@ -38,16 +42,20 @@ typedef struct H {
 } H;
 
 enum J_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   J_Foo,
   J_Bar,
   J_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum J_Tag J_Tag;
+#else
 typedef uint8_t J_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct J_Bar_Body {
@@ -66,16 +74,20 @@ typedef struct J {
 } J;
 
 enum K_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   K_Foo,
   K_Bar,
   K_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum K_Tag K_Tag;
+#else
 typedef uint8_t K_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct K_Bar_Body {
diff --git a/tests/expectations/asserted_cast_tag.c b/tests/expectations/asserted_cast_tag.c
index f953fbe1b..af5a2c3e4 100644
--- a/tests/expectations/asserted_cast_tag.c
+++ b/tests/expectations/asserted_cast_tag.c
@@ -9,12 +9,20 @@
 
 struct I;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   H_Foo,
   H_Bar,
   H_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct H_Bar_Body {
   uint8_t x;
@@ -31,12 +39,20 @@ struct H {
   };
 };
 
-enum J_Tag {
+enum J_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   J_Foo,
   J_Bar,
   J_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum J_Tag J_Tag;
+#else
 typedef uint8_t J_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct J_Bar_Body {
   uint8_t x;
@@ -53,12 +69,20 @@ struct J {
   };
 };
 
-enum K_Tag {
+enum K_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   K_Foo,
   K_Bar,
   K_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum K_Tag K_Tag;
+#else
 typedef uint8_t K_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct K_Bar_Body {
   K_Tag tag;
diff --git a/tests/expectations/asserted_cast_tag.compat.c b/tests/expectations/asserted_cast_tag.compat.c
index 005aadc7d..878f515bf 100644
--- a/tests/expectations/asserted_cast_tag.compat.c
+++ b/tests/expectations/asserted_cast_tag.compat.c
@@ -10,16 +10,20 @@
 struct I;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   H_Foo,
   H_Bar,
   H_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct H_Bar_Body {
@@ -38,16 +42,20 @@ struct H {
 };
 
 enum J_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   J_Foo,
   J_Bar,
   J_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum J_Tag J_Tag;
+#else
 typedef uint8_t J_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct J_Bar_Body {
@@ -66,16 +74,20 @@ struct J {
 };
 
 enum K_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   K_Foo,
   K_Bar,
   K_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum K_Tag K_Tag;
+#else
 typedef uint8_t K_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct K_Bar_Body {
diff --git a/tests/expectations/cfg.c b/tests/expectations/cfg.c
index c5d3d116d..2cd41ceac 100644
--- a/tests/expectations/cfg.c
+++ b/tests/expectations/cfg.c
@@ -13,21 +13,37 @@ DEF M_32 = 0
 #include <stdlib.h>
 
 #if (defined(PLATFORM_UNIX) && defined(X11))
-enum FooType {
+enum FooType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
   C,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum FooType FooType;
+#else
 typedef uint32_t FooType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif
 
 #if (defined(PLATFORM_WIN) || defined(M_32))
-enum BarType {
+enum BarType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
   C,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum BarType BarType;
+#else
 typedef uint32_t BarType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif
 
 typedef struct {
@@ -59,7 +75,11 @@ typedef struct {
 } FooHandle;
 #endif
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C1,
   C2,
 #if defined(PLATFORM_WIN)
@@ -69,7 +89,11 @@ enum C_Tag {
   C5,
 #endif
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 #if defined(PLATFORM_UNIX)
 typedef struct {
diff --git a/tests/expectations/cfg.compat.c b/tests/expectations/cfg.compat.c
index 9532f71af..891e4ca05 100644
--- a/tests/expectations/cfg.compat.c
+++ b/tests/expectations/cfg.compat.c
@@ -14,31 +14,39 @@ DEF M_32 = 0
 
 #if (defined(PLATFORM_UNIX) && defined(X11))
 enum FooType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
   C,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum FooType FooType;
+#else
 typedef uint32_t FooType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 #endif
 
 #if (defined(PLATFORM_WIN) || defined(M_32))
 enum BarType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
   C,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum BarType BarType;
+#else
 typedef uint32_t BarType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 #endif
 
@@ -72,9 +80,9 @@ typedef struct {
 #endif
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C1,
   C2,
@@ -86,7 +94,11 @@ enum C_Tag
 #endif
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 #if defined(PLATFORM_UNIX)
diff --git a/tests/expectations/cfg_both.c b/tests/expectations/cfg_both.c
index 71e7e8a4e..e0fd3b6b9 100644
--- a/tests/expectations/cfg_both.c
+++ b/tests/expectations/cfg_both.c
@@ -13,21 +13,37 @@ DEF M_32 = 0
 #include <stdlib.h>
 
 #if (defined(PLATFORM_UNIX) && defined(X11))
-enum FooType {
+enum FooType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
   C,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum FooType FooType;
+#else
 typedef uint32_t FooType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif
 
 #if (defined(PLATFORM_WIN) || defined(M_32))
-enum BarType {
+enum BarType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
   C,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum BarType BarType;
+#else
 typedef uint32_t BarType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif
 
 typedef struct Flags {
@@ -59,7 +75,11 @@ typedef struct FooHandle {
 } FooHandle;
 #endif
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C1,
   C2,
 #if defined(PLATFORM_WIN)
@@ -69,7 +89,11 @@ enum C_Tag {
   C5,
 #endif
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 #if defined(PLATFORM_UNIX)
 typedef struct C5_Body {
diff --git a/tests/expectations/cfg_both.compat.c b/tests/expectations/cfg_both.compat.c
index bedee0d7e..b4bc7f7e2 100644
--- a/tests/expectations/cfg_both.compat.c
+++ b/tests/expectations/cfg_both.compat.c
@@ -14,31 +14,39 @@ DEF M_32 = 0
 
 #if (defined(PLATFORM_UNIX) && defined(X11))
 enum FooType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
   C,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum FooType FooType;
+#else
 typedef uint32_t FooType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 #endif
 
 #if (defined(PLATFORM_WIN) || defined(M_32))
 enum BarType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
   C,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum BarType BarType;
+#else
 typedef uint32_t BarType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 #endif
 
@@ -72,9 +80,9 @@ typedef struct FooHandle {
 #endif
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C1,
   C2,
@@ -86,7 +94,11 @@ enum C_Tag
 #endif
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 #if defined(PLATFORM_UNIX)
diff --git a/tests/expectations/cfg_tag.c b/tests/expectations/cfg_tag.c
index 96ccf90cd..aab076d66 100644
--- a/tests/expectations/cfg_tag.c
+++ b/tests/expectations/cfg_tag.c
@@ -13,21 +13,37 @@ DEF M_32 = 0
 #include <stdlib.h>
 
 #if (defined(PLATFORM_UNIX) && defined(X11))
-enum FooType {
+enum FooType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
   C,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum FooType FooType;
+#else
 typedef uint32_t FooType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif
 
 #if (defined(PLATFORM_WIN) || defined(M_32))
-enum BarType {
+enum BarType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
   C,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum BarType BarType;
+#else
 typedef uint32_t BarType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif
 
 struct Flags {
@@ -59,7 +75,11 @@ struct FooHandle {
 };
 #endif
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C1,
   C2,
 #if defined(PLATFORM_WIN)
@@ -69,7 +89,11 @@ enum C_Tag {
   C5,
 #endif
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 #if defined(PLATFORM_UNIX)
 struct C5_Body {
diff --git a/tests/expectations/cfg_tag.compat.c b/tests/expectations/cfg_tag.compat.c
index ec879c687..b10a46dc2 100644
--- a/tests/expectations/cfg_tag.compat.c
+++ b/tests/expectations/cfg_tag.compat.c
@@ -14,31 +14,39 @@ DEF M_32 = 0
 
 #if (defined(PLATFORM_UNIX) && defined(X11))
 enum FooType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
   C,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum FooType FooType;
+#else
 typedef uint32_t FooType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 #endif
 
 #if (defined(PLATFORM_WIN) || defined(M_32))
 enum BarType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
   C,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum BarType BarType;
+#else
 typedef uint32_t BarType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 #endif
 
@@ -72,9 +80,9 @@ struct FooHandle {
 #endif
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C1,
   C2,
@@ -86,7 +94,11 @@ enum C_Tag
 #endif
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 #if defined(PLATFORM_UNIX)
diff --git a/tests/expectations/decl_name_conflicting.c b/tests/expectations/decl_name_conflicting.c
index 41a148e4d..a92617fc6 100644
--- a/tests/expectations/decl_name_conflicting.c
+++ b/tests/expectations/decl_name_conflicting.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum BindingType {
+enum BindingType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Buffer = 0,
   NotBuffer = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum BindingType BindingType;
+#else
 typedef uint32_t BindingType;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   BindingType ty;
diff --git a/tests/expectations/decl_name_conflicting.compat.c b/tests/expectations/decl_name_conflicting.compat.c
index 6866bb812..5a65c879e 100644
--- a/tests/expectations/decl_name_conflicting.compat.c
+++ b/tests/expectations/decl_name_conflicting.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum BindingType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Buffer = 0,
   NotBuffer = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum BindingType BindingType;
+#else
 typedef uint32_t BindingType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/decl_name_conflicting_both.c b/tests/expectations/decl_name_conflicting_both.c
index 486b31c60..8a5cec24a 100644
--- a/tests/expectations/decl_name_conflicting_both.c
+++ b/tests/expectations/decl_name_conflicting_both.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum BindingType {
+enum BindingType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Buffer = 0,
   NotBuffer = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum BindingType BindingType;
+#else
 typedef uint32_t BindingType;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct BindGroupLayoutEntry {
   BindingType ty;
diff --git a/tests/expectations/decl_name_conflicting_both.compat.c b/tests/expectations/decl_name_conflicting_both.compat.c
index 143f0d1dc..352317a6f 100644
--- a/tests/expectations/decl_name_conflicting_both.compat.c
+++ b/tests/expectations/decl_name_conflicting_both.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum BindingType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Buffer = 0,
   NotBuffer = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum BindingType BindingType;
+#else
 typedef uint32_t BindingType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct BindGroupLayoutEntry {
diff --git a/tests/expectations/decl_name_conflicting_tag.c b/tests/expectations/decl_name_conflicting_tag.c
index 7504e4aad..e7c513d06 100644
--- a/tests/expectations/decl_name_conflicting_tag.c
+++ b/tests/expectations/decl_name_conflicting_tag.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum BindingType {
+enum BindingType
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Buffer = 0,
   NotBuffer = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum BindingType BindingType;
+#else
 typedef uint32_t BindingType;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct BindGroupLayoutEntry {
   BindingType ty;
diff --git a/tests/expectations/decl_name_conflicting_tag.compat.c b/tests/expectations/decl_name_conflicting_tag.compat.c
index df722be00..c94741f24 100644
--- a/tests/expectations/decl_name_conflicting_tag.compat.c
+++ b/tests/expectations/decl_name_conflicting_tag.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum BindingType
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Buffer = 0,
   NotBuffer = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum BindingType BindingType;
+#else
 typedef uint32_t BindingType;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct BindGroupLayoutEntry {
diff --git a/tests/expectations/deprecated.c b/tests/expectations/deprecated.c
index 48f5574d8..3c76c3d1a 100644
--- a/tests/expectations/deprecated.c
+++ b/tests/expectations/deprecated.c
@@ -13,23 +13,47 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum DEPRECATED_ENUM DeprecatedEnum {
+enum DEPRECATED_ENUM DeprecatedEnum
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A = 0,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnum DeprecatedEnum;
+#else
 typedef int32_t DeprecatedEnum;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote {
+enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   B = 0,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnumWithNote DeprecatedEnumWithNote;
+#else
 typedef int32_t DeprecatedEnumWithNote;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum EnumWithDeprecatedVariants {
+enum EnumWithDeprecatedVariants
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C = 0,
   D DEPRECATED_ENUM_VARIANT = 1,
   E DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 2,
   F DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedVariants EnumWithDeprecatedVariants;
+#else
 typedef int32_t EnumWithDeprecatedVariants;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct DEPRECATED_STRUCT {
   int32_t a;
@@ -39,12 +63,20 @@ typedef struct DEPRECATED_STRUCT_WITH_NOTE("This is a note") {
   int32_t a;
 } DeprecatedStructWithNote;
 
-enum EnumWithDeprecatedStructVariants_Tag {
+enum EnumWithDeprecatedStructVariants_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar DEPRECATED_ENUM_VARIANT,
   Baz DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note"),
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedStructVariants_Tag EnumWithDeprecatedStructVariants_Tag;
+#else
 typedef uint8_t EnumWithDeprecatedStructVariants_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct DEPRECATED_STRUCT {
   EnumWithDeprecatedStructVariants_Tag tag;
diff --git a/tests/expectations/deprecated.compat.c b/tests/expectations/deprecated.compat.c
index dcdede489..0a4b25d49 100644
--- a/tests/expectations/deprecated.compat.c
+++ b/tests/expectations/deprecated.compat.c
@@ -14,31 +14,39 @@
 #include <stdlib.h>
 
 enum DEPRECATED_ENUM DeprecatedEnum
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A = 0,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnum DeprecatedEnum;
+#else
 typedef int32_t DeprecatedEnum;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   B = 0,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnumWithNote DeprecatedEnumWithNote;
+#else
 typedef int32_t DeprecatedEnumWithNote;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum EnumWithDeprecatedVariants
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C = 0,
   D DEPRECATED_ENUM_VARIANT = 1,
@@ -46,7 +54,11 @@ enum EnumWithDeprecatedVariants
   F DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedVariants EnumWithDeprecatedVariants;
+#else
 typedef int32_t EnumWithDeprecatedVariants;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct DEPRECATED_STRUCT {
@@ -58,16 +70,20 @@ typedef struct DEPRECATED_STRUCT_WITH_NOTE("This is a note") {
 } DeprecatedStructWithNote;
 
 enum EnumWithDeprecatedStructVariants_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar DEPRECATED_ENUM_VARIANT,
   Baz DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note"),
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedStructVariants_Tag EnumWithDeprecatedStructVariants_Tag;
+#else
 typedef uint8_t EnumWithDeprecatedStructVariants_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct DEPRECATED_STRUCT {
diff --git a/tests/expectations/deprecated_both.c b/tests/expectations/deprecated_both.c
index e2713c4d1..980225002 100644
--- a/tests/expectations/deprecated_both.c
+++ b/tests/expectations/deprecated_both.c
@@ -13,23 +13,47 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum DEPRECATED_ENUM DeprecatedEnum {
+enum DEPRECATED_ENUM DeprecatedEnum
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A = 0,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnum DeprecatedEnum;
+#else
 typedef int32_t DeprecatedEnum;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote {
+enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   B = 0,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnumWithNote DeprecatedEnumWithNote;
+#else
 typedef int32_t DeprecatedEnumWithNote;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum EnumWithDeprecatedVariants {
+enum EnumWithDeprecatedVariants
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C = 0,
   D DEPRECATED_ENUM_VARIANT = 1,
   E DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 2,
   F DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedVariants EnumWithDeprecatedVariants;
+#else
 typedef int32_t EnumWithDeprecatedVariants;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct DEPRECATED_STRUCT DeprecatedStruct {
   int32_t a;
@@ -39,12 +63,20 @@ typedef struct DEPRECATED_STRUCT_WITH_NOTE("This is a note") DeprecatedStructWit
   int32_t a;
 } DeprecatedStructWithNote;
 
-enum EnumWithDeprecatedStructVariants_Tag {
+enum EnumWithDeprecatedStructVariants_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar DEPRECATED_ENUM_VARIANT,
   Baz DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note"),
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedStructVariants_Tag EnumWithDeprecatedStructVariants_Tag;
+#else
 typedef uint8_t EnumWithDeprecatedStructVariants_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct DEPRECATED_STRUCT Bar_Body {
   EnumWithDeprecatedStructVariants_Tag tag;
diff --git a/tests/expectations/deprecated_both.compat.c b/tests/expectations/deprecated_both.compat.c
index 479aa730f..d01596c7f 100644
--- a/tests/expectations/deprecated_both.compat.c
+++ b/tests/expectations/deprecated_both.compat.c
@@ -14,31 +14,39 @@
 #include <stdlib.h>
 
 enum DEPRECATED_ENUM DeprecatedEnum
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A = 0,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnum DeprecatedEnum;
+#else
 typedef int32_t DeprecatedEnum;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   B = 0,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnumWithNote DeprecatedEnumWithNote;
+#else
 typedef int32_t DeprecatedEnumWithNote;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum EnumWithDeprecatedVariants
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C = 0,
   D DEPRECATED_ENUM_VARIANT = 1,
@@ -46,7 +54,11 @@ enum EnumWithDeprecatedVariants
   F DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedVariants EnumWithDeprecatedVariants;
+#else
 typedef int32_t EnumWithDeprecatedVariants;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct DEPRECATED_STRUCT DeprecatedStruct {
@@ -58,16 +70,20 @@ typedef struct DEPRECATED_STRUCT_WITH_NOTE("This is a note") DeprecatedStructWit
 } DeprecatedStructWithNote;
 
 enum EnumWithDeprecatedStructVariants_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar DEPRECATED_ENUM_VARIANT,
   Baz DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note"),
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedStructVariants_Tag EnumWithDeprecatedStructVariants_Tag;
+#else
 typedef uint8_t EnumWithDeprecatedStructVariants_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct DEPRECATED_STRUCT Bar_Body {
diff --git a/tests/expectations/deprecated_tag.c b/tests/expectations/deprecated_tag.c
index 982cdc555..521d0f38a 100644
--- a/tests/expectations/deprecated_tag.c
+++ b/tests/expectations/deprecated_tag.c
@@ -13,23 +13,47 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum DEPRECATED_ENUM DeprecatedEnum {
+enum DEPRECATED_ENUM DeprecatedEnum
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A = 0,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnum DeprecatedEnum;
+#else
 typedef int32_t DeprecatedEnum;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote {
+enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   B = 0,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnumWithNote DeprecatedEnumWithNote;
+#else
 typedef int32_t DeprecatedEnumWithNote;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum EnumWithDeprecatedVariants {
+enum EnumWithDeprecatedVariants
+#if __STDC_VERSION__ >= 202311L
+  : int32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C = 0,
   D DEPRECATED_ENUM_VARIANT = 1,
   E DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 2,
   F DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedVariants EnumWithDeprecatedVariants;
+#else
 typedef int32_t EnumWithDeprecatedVariants;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct DEPRECATED_STRUCT DeprecatedStruct {
   int32_t a;
@@ -39,12 +63,20 @@ struct DEPRECATED_STRUCT_WITH_NOTE("This is a note") DeprecatedStructWithNote {
   int32_t a;
 };
 
-enum EnumWithDeprecatedStructVariants_Tag {
+enum EnumWithDeprecatedStructVariants_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar DEPRECATED_ENUM_VARIANT,
   Baz DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note"),
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedStructVariants_Tag EnumWithDeprecatedStructVariants_Tag;
+#else
 typedef uint8_t EnumWithDeprecatedStructVariants_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct DEPRECATED_STRUCT Bar_Body {
   EnumWithDeprecatedStructVariants_Tag tag;
diff --git a/tests/expectations/deprecated_tag.compat.c b/tests/expectations/deprecated_tag.compat.c
index 322b79d25..14c32b250 100644
--- a/tests/expectations/deprecated_tag.compat.c
+++ b/tests/expectations/deprecated_tag.compat.c
@@ -14,31 +14,39 @@
 #include <stdlib.h>
 
 enum DEPRECATED_ENUM DeprecatedEnum
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A = 0,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnum DeprecatedEnum;
+#else
 typedef int32_t DeprecatedEnum;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum DEPRECATED_ENUM_WITH_NOTE("This is a note") DeprecatedEnumWithNote
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   B = 0,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DeprecatedEnumWithNote DeprecatedEnumWithNote;
+#else
 typedef int32_t DeprecatedEnumWithNote;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum EnumWithDeprecatedVariants
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C = 0,
   D DEPRECATED_ENUM_VARIANT = 1,
@@ -46,7 +54,11 @@ enum EnumWithDeprecatedVariants
   F DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note") = 3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedVariants EnumWithDeprecatedVariants;
+#else
 typedef int32_t EnumWithDeprecatedVariants;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct DEPRECATED_STRUCT DeprecatedStruct {
@@ -58,16 +70,20 @@ struct DEPRECATED_STRUCT_WITH_NOTE("This is a note") DeprecatedStructWithNote {
 };
 
 enum EnumWithDeprecatedStructVariants_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar DEPRECATED_ENUM_VARIANT,
   Baz DEPRECATED_ENUM_VARIANT_WITH_NOTE("This is a note"),
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum EnumWithDeprecatedStructVariants_Tag EnumWithDeprecatedStructVariants_Tag;
+#else
 typedef uint8_t EnumWithDeprecatedStructVariants_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct DEPRECATED_STRUCT Bar_Body {
diff --git a/tests/expectations/derive_eq.c b/tests/expectations/derive_eq.c
index 339a937d1..eb29ef81a 100644
--- a/tests/expectations/derive_eq.c
+++ b/tests/expectations/derive_eq.c
@@ -8,13 +8,21 @@ typedef struct {
   int32_t b;
 } Foo;
 
-enum Bar_Tag {
+enum Bar_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Baz,
   Bazz,
   FooNamed,
   FooParen,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   Bar_Tag tag;
diff --git a/tests/expectations/derive_eq.compat.c b/tests/expectations/derive_eq.compat.c
index d3037f88a..b1cf09ddd 100644
--- a/tests/expectations/derive_eq.compat.c
+++ b/tests/expectations/derive_eq.compat.c
@@ -9,9 +9,9 @@ typedef struct {
 } Foo;
 
 enum Bar_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Baz,
   Bazz,
@@ -19,7 +19,11 @@ enum Bar_Tag
   FooParen,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/derive_eq_both.c b/tests/expectations/derive_eq_both.c
index eab5b1c16..e64618bf9 100644
--- a/tests/expectations/derive_eq_both.c
+++ b/tests/expectations/derive_eq_both.c
@@ -8,13 +8,21 @@ typedef struct Foo {
   int32_t b;
 } Foo;
 
-enum Bar_Tag {
+enum Bar_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Baz,
   Bazz,
   FooNamed,
   FooParen,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Bazz_Body {
   Bar_Tag tag;
diff --git a/tests/expectations/derive_eq_both.compat.c b/tests/expectations/derive_eq_both.compat.c
index 1a0a366c4..ffad7da29 100644
--- a/tests/expectations/derive_eq_both.compat.c
+++ b/tests/expectations/derive_eq_both.compat.c
@@ -9,9 +9,9 @@ typedef struct Foo {
 } Foo;
 
 enum Bar_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Baz,
   Bazz,
@@ -19,7 +19,11 @@ enum Bar_Tag
   FooParen,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Bazz_Body {
diff --git a/tests/expectations/derive_eq_tag.c b/tests/expectations/derive_eq_tag.c
index 4de1da99f..ad6909895 100644
--- a/tests/expectations/derive_eq_tag.c
+++ b/tests/expectations/derive_eq_tag.c
@@ -8,13 +8,21 @@ struct Foo {
   int32_t b;
 };
 
-enum Bar_Tag {
+enum Bar_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Baz,
   Bazz,
   FooNamed,
   FooParen,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Bazz_Body {
   Bar_Tag tag;
diff --git a/tests/expectations/derive_eq_tag.compat.c b/tests/expectations/derive_eq_tag.compat.c
index 66f02aed1..7c074a1bb 100644
--- a/tests/expectations/derive_eq_tag.compat.c
+++ b/tests/expectations/derive_eq_tag.compat.c
@@ -9,9 +9,9 @@ struct Foo {
 };
 
 enum Bar_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Baz,
   Bazz,
@@ -19,7 +19,11 @@ enum Bar_Tag
   FooParen,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Bazz_Body {
diff --git a/tests/expectations/derive_ostream.c b/tests/expectations/derive_ostream.c
index 2db696dba..ed1971aca 100644
--- a/tests/expectations/derive_ostream.c
+++ b/tests/expectations/derive_ostream.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   int32_t _0;
@@ -24,12 +32,20 @@ typedef struct {
   B Things;
 } D;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   F_Tag tag;
@@ -46,12 +62,20 @@ typedef union {
   Bar_Body bar;
 } F;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;
@@ -68,11 +92,19 @@ typedef struct {
   };
 } H;
 
-enum I_Tag {
+enum I_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   ThereAgain,
   SomethingElse,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum I_Tag I_Tag;
+#else
 typedef uint8_t I_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;
diff --git a/tests/expectations/derive_ostream.compat.c b/tests/expectations/derive_ostream.compat.c
index e235353db..a5c0ac3a7 100644
--- a/tests/expectations/derive_ostream.compat.c
+++ b/tests/expectations/derive_ostream.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -31,16 +35,20 @@ typedef struct {
 } D;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -59,16 +67,20 @@ typedef union {
 } F;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -87,15 +99,19 @@ typedef struct {
 } H;
 
 enum I_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   ThereAgain,
   SomethingElse,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum I_Tag I_Tag;
+#else
 typedef uint8_t I_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/derive_ostream_both.c b/tests/expectations/derive_ostream_both.c
index 8f45660e0..b106f85de 100644
--- a/tests/expectations/derive_ostream_both.c
+++ b/tests/expectations/derive_ostream_both.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct A {
   int32_t _0;
@@ -24,12 +32,20 @@ typedef struct D {
   struct B Things;
 } D;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Bar_Body {
   F_Tag tag;
@@ -46,12 +62,20 @@ typedef union F {
   Bar_Body bar;
 } F;
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct There_Body {
   uint8_t x;
@@ -68,11 +92,19 @@ typedef struct H {
   };
 } H;
 
-enum I_Tag {
+enum I_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   ThereAgain,
   SomethingElse,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum I_Tag I_Tag;
+#else
 typedef uint8_t I_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct ThereAgain_Body {
   uint8_t x;
diff --git a/tests/expectations/derive_ostream_both.compat.c b/tests/expectations/derive_ostream_both.compat.c
index 69165d1d2..d5ec5197b 100644
--- a/tests/expectations/derive_ostream_both.compat.c
+++ b/tests/expectations/derive_ostream_both.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct A {
@@ -31,16 +35,20 @@ typedef struct D {
 } D;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Bar_Body {
@@ -59,16 +67,20 @@ typedef union F {
 } F;
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct There_Body {
@@ -87,15 +99,19 @@ typedef struct H {
 } H;
 
 enum I_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   ThereAgain,
   SomethingElse,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum I_Tag I_Tag;
+#else
 typedef uint8_t I_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct ThereAgain_Body {
diff --git a/tests/expectations/derive_ostream_tag.c b/tests/expectations/derive_ostream_tag.c
index 4217a4be6..fe0dae70b 100644
--- a/tests/expectations/derive_ostream_tag.c
+++ b/tests/expectations/derive_ostream_tag.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   X = 2,
   Y,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct A {
   int32_t _0;
@@ -24,12 +32,20 @@ struct D {
   struct B Things;
 };
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Bar_Body {
   F_Tag tag;
@@ -46,12 +62,20 @@ union F {
   struct Bar_Body bar;
 };
 
-enum H_Tag {
+enum H_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Hello,
   There,
   Everyone,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct There_Body {
   uint8_t x;
@@ -68,11 +92,19 @@ struct H {
   };
 };
 
-enum I_Tag {
+enum I_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   ThereAgain,
   SomethingElse,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum I_Tag I_Tag;
+#else
 typedef uint8_t I_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct ThereAgain_Body {
   uint8_t x;
diff --git a/tests/expectations/derive_ostream_tag.compat.c b/tests/expectations/derive_ostream_tag.compat.c
index f7b1b77b0..a6d4af02f 100644
--- a/tests/expectations/derive_ostream_tag.compat.c
+++ b/tests/expectations/derive_ostream_tag.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   X = 2,
   Y,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint32_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct A {
@@ -31,16 +35,20 @@ struct D {
 };
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Bar_Body {
@@ -59,16 +67,20 @@ union F {
 };
 
 enum H_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Hello,
   There,
   Everyone,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum H_Tag H_Tag;
+#else
 typedef uint8_t H_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct There_Body {
@@ -87,15 +99,19 @@ struct H {
 };
 
 enum I_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   ThereAgain,
   SomethingElse,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum I_Tag I_Tag;
+#else
 typedef uint8_t I_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct ThereAgain_Body {
diff --git a/tests/expectations/destructor_and_copy_ctor.c b/tests/expectations/destructor_and_copy_ctor.c
index 0f616ab26..a3ae1e1d6 100644
--- a/tests/expectations/destructor_and_copy_ctor.c
+++ b/tests/expectations/destructor_and_copy_ctor.c
@@ -7,11 +7,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum FillRule {
+enum FillRule
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum FillRule FillRule;
+#else
 typedef uint8_t FillRule;
+#endif // __STDC_VERSION__ >= 202311L
 
 /**
  * This will have a destructor manually implemented via variant_body, and
@@ -36,7 +44,11 @@ typedef struct {
   int32_t *ptr;
 } OwnedSlice_i32;
 
-enum Foo_u32_Tag {
+enum Foo_u32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar_u32,
   Polygon1_u32,
   Slice1_u32,
@@ -44,7 +56,11 @@ enum Foo_u32_Tag {
   Slice3_u32,
   Slice4_u32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Foo_u32_Tag Foo_u32_Tag;
+#else
 typedef uint8_t Foo_u32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   FillRule fill;
@@ -78,7 +94,11 @@ typedef struct {
   OwnedSlice_i32 coordinates;
 } Polygon_i32;
 
-enum Baz_i32_Tag {
+enum Baz_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar2_i32,
   Polygon21_i32,
   Slice21_i32,
@@ -86,7 +106,11 @@ enum Baz_i32_Tag {
   Slice23_i32,
   Slice24_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Baz_i32_Tag Baz_i32_Tag;
+#else
 typedef uint8_t Baz_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   Baz_i32_Tag tag;
@@ -118,12 +142,20 @@ typedef union {
   Slice24_Body_i32 slice24;
 } Baz_i32;
 
-enum Taz_Tag {
+enum Taz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar3,
   Taz1,
   Taz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Taz_Tag Taz_Tag;
+#else
 typedef uint8_t Taz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   Taz_Tag tag;
@@ -137,11 +169,19 @@ typedef union {
   };
 } Taz;
 
-enum Tazz_Tag {
+enum Tazz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar4,
   Taz2,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazz_Tag Tazz_Tag;
+#else
 typedef uint8_t Tazz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   Tazz_Tag tag;
@@ -151,11 +191,19 @@ typedef union {
   };
 } Tazz;
 
-enum Tazzz_Tag {
+enum Tazzz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar5,
   Taz5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzz_Tag Tazzz_Tag;
+#else
 typedef uint8_t Tazzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   Tazzz_Tag tag;
@@ -165,11 +213,19 @@ typedef union {
   };
 } Tazzz;
 
-enum Tazzzz_Tag {
+enum Tazzzz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Taz6,
   Taz7,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzzz_Tag Tazzzz_Tag;
+#else
 typedef uint8_t Tazzzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   Tazzzz_Tag tag;
@@ -183,11 +239,19 @@ typedef union {
   };
 } Tazzzz;
 
-enum Qux_Tag {
+enum Qux_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Qux1,
   Qux2,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Qux_Tag Qux_Tag;
+#else
 typedef uint8_t Qux_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   Qux_Tag tag;
diff --git a/tests/expectations/destructor_and_copy_ctor.compat.c b/tests/expectations/destructor_and_copy_ctor.compat.c
index f12119b0d..5c48a4909 100644
--- a/tests/expectations/destructor_and_copy_ctor.compat.c
+++ b/tests/expectations/destructor_and_copy_ctor.compat.c
@@ -8,15 +8,19 @@
 #include <stdlib.h>
 
 enum FillRule
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum FillRule FillRule;
+#else
 typedef uint8_t FillRule;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 /**
@@ -43,9 +47,9 @@ typedef struct {
 } OwnedSlice_i32;
 
 enum Foo_u32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar_u32,
   Polygon1_u32,
@@ -55,7 +59,11 @@ enum Foo_u32_Tag
   Slice4_u32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Foo_u32_Tag Foo_u32_Tag;
+#else
 typedef uint8_t Foo_u32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -91,9 +99,9 @@ typedef struct {
 } Polygon_i32;
 
 enum Baz_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar2_i32,
   Polygon21_i32,
@@ -103,7 +111,11 @@ enum Baz_i32_Tag
   Slice24_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Baz_i32_Tag Baz_i32_Tag;
+#else
 typedef uint8_t Baz_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -137,16 +149,20 @@ typedef union {
 } Baz_i32;
 
 enum Taz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar3,
   Taz1,
   Taz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Taz_Tag Taz_Tag;
+#else
 typedef uint8_t Taz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
@@ -162,15 +178,19 @@ typedef union {
 } Taz;
 
 enum Tazz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar4,
   Taz2,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazz_Tag Tazz_Tag;
+#else
 typedef uint8_t Tazz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
@@ -182,15 +202,19 @@ typedef union {
 } Tazz;
 
 enum Tazzz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar5,
   Taz5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzz_Tag Tazzz_Tag;
+#else
 typedef uint8_t Tazzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
@@ -202,15 +226,19 @@ typedef union {
 } Tazzz;
 
 enum Tazzzz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Taz6,
   Taz7,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzzz_Tag Tazzzz_Tag;
+#else
 typedef uint8_t Tazzzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
@@ -226,15 +254,19 @@ typedef union {
 } Tazzzz;
 
 enum Qux_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Qux1,
   Qux2,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Qux_Tag Qux_Tag;
+#else
 typedef uint8_t Qux_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
diff --git a/tests/expectations/destructor_and_copy_ctor_both.c b/tests/expectations/destructor_and_copy_ctor_both.c
index 12910395b..dacdb22ad 100644
--- a/tests/expectations/destructor_and_copy_ctor_both.c
+++ b/tests/expectations/destructor_and_copy_ctor_both.c
@@ -7,11 +7,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum FillRule {
+enum FillRule
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum FillRule FillRule;
+#else
 typedef uint8_t FillRule;
+#endif // __STDC_VERSION__ >= 202311L
 
 /**
  * This will have a destructor manually implemented via variant_body, and
@@ -36,7 +44,11 @@ typedef struct OwnedSlice_i32 {
   int32_t *ptr;
 } OwnedSlice_i32;
 
-enum Foo_u32_Tag {
+enum Foo_u32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar_u32,
   Polygon1_u32,
   Slice1_u32,
@@ -44,7 +56,11 @@ enum Foo_u32_Tag {
   Slice3_u32,
   Slice4_u32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Foo_u32_Tag Foo_u32_Tag;
+#else
 typedef uint8_t Foo_u32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Slice3_Body_u32 {
   FillRule fill;
@@ -78,7 +94,11 @@ typedef struct Polygon_i32 {
   struct OwnedSlice_i32 coordinates;
 } Polygon_i32;
 
-enum Baz_i32_Tag {
+enum Baz_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar2_i32,
   Polygon21_i32,
   Slice21_i32,
@@ -86,7 +106,11 @@ enum Baz_i32_Tag {
   Slice23_i32,
   Slice24_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Baz_i32_Tag Baz_i32_Tag;
+#else
 typedef uint8_t Baz_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Slice23_Body_i32 {
   Baz_i32_Tag tag;
@@ -118,12 +142,20 @@ typedef union Baz_i32 {
   Slice24_Body_i32 slice24;
 } Baz_i32;
 
-enum Taz_Tag {
+enum Taz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar3,
   Taz1,
   Taz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Taz_Tag Taz_Tag;
+#else
 typedef uint8_t Taz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union Taz {
   Taz_Tag tag;
@@ -137,11 +169,19 @@ typedef union Taz {
   };
 } Taz;
 
-enum Tazz_Tag {
+enum Tazz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar4,
   Taz2,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazz_Tag Tazz_Tag;
+#else
 typedef uint8_t Tazz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union Tazz {
   Tazz_Tag tag;
@@ -151,11 +191,19 @@ typedef union Tazz {
   };
 } Tazz;
 
-enum Tazzz_Tag {
+enum Tazzz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar5,
   Taz5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzz_Tag Tazzz_Tag;
+#else
 typedef uint8_t Tazzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union Tazzz {
   Tazzz_Tag tag;
@@ -165,11 +213,19 @@ typedef union Tazzz {
   };
 } Tazzz;
 
-enum Tazzzz_Tag {
+enum Tazzzz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Taz6,
   Taz7,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzzz_Tag Tazzzz_Tag;
+#else
 typedef uint8_t Tazzzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union Tazzzz {
   Tazzzz_Tag tag;
@@ -183,11 +239,19 @@ typedef union Tazzzz {
   };
 } Tazzzz;
 
-enum Qux_Tag {
+enum Qux_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Qux1,
   Qux2,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Qux_Tag Qux_Tag;
+#else
 typedef uint8_t Qux_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union Qux {
   Qux_Tag tag;
diff --git a/tests/expectations/destructor_and_copy_ctor_both.compat.c b/tests/expectations/destructor_and_copy_ctor_both.compat.c
index d151c7d81..797439842 100644
--- a/tests/expectations/destructor_and_copy_ctor_both.compat.c
+++ b/tests/expectations/destructor_and_copy_ctor_both.compat.c
@@ -8,15 +8,19 @@
 #include <stdlib.h>
 
 enum FillRule
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum FillRule FillRule;
+#else
 typedef uint8_t FillRule;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 /**
@@ -43,9 +47,9 @@ typedef struct OwnedSlice_i32 {
 } OwnedSlice_i32;
 
 enum Foo_u32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar_u32,
   Polygon1_u32,
@@ -55,7 +59,11 @@ enum Foo_u32_Tag
   Slice4_u32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Foo_u32_Tag Foo_u32_Tag;
+#else
 typedef uint8_t Foo_u32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Slice3_Body_u32 {
@@ -91,9 +99,9 @@ typedef struct Polygon_i32 {
 } Polygon_i32;
 
 enum Baz_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar2_i32,
   Polygon21_i32,
@@ -103,7 +111,11 @@ enum Baz_i32_Tag
   Slice24_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Baz_i32_Tag Baz_i32_Tag;
+#else
 typedef uint8_t Baz_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Slice23_Body_i32 {
@@ -137,16 +149,20 @@ typedef union Baz_i32 {
 } Baz_i32;
 
 enum Taz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar3,
   Taz1,
   Taz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Taz_Tag Taz_Tag;
+#else
 typedef uint8_t Taz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union Taz {
@@ -162,15 +178,19 @@ typedef union Taz {
 } Taz;
 
 enum Tazz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar4,
   Taz2,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazz_Tag Tazz_Tag;
+#else
 typedef uint8_t Tazz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union Tazz {
@@ -182,15 +202,19 @@ typedef union Tazz {
 } Tazz;
 
 enum Tazzz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar5,
   Taz5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzz_Tag Tazzz_Tag;
+#else
 typedef uint8_t Tazzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union Tazzz {
@@ -202,15 +226,19 @@ typedef union Tazzz {
 } Tazzz;
 
 enum Tazzzz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Taz6,
   Taz7,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzzz_Tag Tazzzz_Tag;
+#else
 typedef uint8_t Tazzzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union Tazzzz {
@@ -226,15 +254,19 @@ typedef union Tazzzz {
 } Tazzzz;
 
 enum Qux_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Qux1,
   Qux2,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Qux_Tag Qux_Tag;
+#else
 typedef uint8_t Qux_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union Qux {
diff --git a/tests/expectations/destructor_and_copy_ctor_tag.c b/tests/expectations/destructor_and_copy_ctor_tag.c
index 537ec6f73..bcd82fb6f 100644
--- a/tests/expectations/destructor_and_copy_ctor_tag.c
+++ b/tests/expectations/destructor_and_copy_ctor_tag.c
@@ -7,11 +7,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum FillRule {
+enum FillRule
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A,
   B,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum FillRule FillRule;
+#else
 typedef uint8_t FillRule;
+#endif // __STDC_VERSION__ >= 202311L
 
 /**
  * This will have a destructor manually implemented via variant_body, and
@@ -36,7 +44,11 @@ struct OwnedSlice_i32 {
   int32_t *ptr;
 };
 
-enum Foo_u32_Tag {
+enum Foo_u32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar_u32,
   Polygon1_u32,
   Slice1_u32,
@@ -44,7 +56,11 @@ enum Foo_u32_Tag {
   Slice3_u32,
   Slice4_u32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Foo_u32_Tag Foo_u32_Tag;
+#else
 typedef uint8_t Foo_u32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Slice3_Body_u32 {
   FillRule fill;
@@ -78,7 +94,11 @@ struct Polygon_i32 {
   struct OwnedSlice_i32 coordinates;
 };
 
-enum Baz_i32_Tag {
+enum Baz_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar2_i32,
   Polygon21_i32,
   Slice21_i32,
@@ -86,7 +106,11 @@ enum Baz_i32_Tag {
   Slice23_i32,
   Slice24_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Baz_i32_Tag Baz_i32_Tag;
+#else
 typedef uint8_t Baz_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Slice23_Body_i32 {
   Baz_i32_Tag tag;
@@ -118,12 +142,20 @@ union Baz_i32 {
   struct Slice24_Body_i32 slice24;
 };
 
-enum Taz_Tag {
+enum Taz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar3,
   Taz1,
   Taz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Taz_Tag Taz_Tag;
+#else
 typedef uint8_t Taz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union Taz {
   Taz_Tag tag;
@@ -137,11 +169,19 @@ union Taz {
   };
 };
 
-enum Tazz_Tag {
+enum Tazz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar4,
   Taz2,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazz_Tag Tazz_Tag;
+#else
 typedef uint8_t Tazz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union Tazz {
   Tazz_Tag tag;
@@ -151,11 +191,19 @@ union Tazz {
   };
 };
 
-enum Tazzz_Tag {
+enum Tazzz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Bar5,
   Taz5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzz_Tag Tazzz_Tag;
+#else
 typedef uint8_t Tazzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union Tazzz {
   Tazzz_Tag tag;
@@ -165,11 +213,19 @@ union Tazzz {
   };
 };
 
-enum Tazzzz_Tag {
+enum Tazzzz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Taz6,
   Taz7,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzzz_Tag Tazzzz_Tag;
+#else
 typedef uint8_t Tazzzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union Tazzzz {
   Tazzzz_Tag tag;
@@ -183,11 +239,19 @@ union Tazzzz {
   };
 };
 
-enum Qux_Tag {
+enum Qux_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Qux1,
   Qux2,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Qux_Tag Qux_Tag;
+#else
 typedef uint8_t Qux_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union Qux {
   Qux_Tag tag;
diff --git a/tests/expectations/destructor_and_copy_ctor_tag.compat.c b/tests/expectations/destructor_and_copy_ctor_tag.compat.c
index e6233263b..7556102b5 100644
--- a/tests/expectations/destructor_and_copy_ctor_tag.compat.c
+++ b/tests/expectations/destructor_and_copy_ctor_tag.compat.c
@@ -8,15 +8,19 @@
 #include <stdlib.h>
 
 enum FillRule
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A,
   B,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum FillRule FillRule;
+#else
 typedef uint8_t FillRule;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 /**
@@ -43,9 +47,9 @@ struct OwnedSlice_i32 {
 };
 
 enum Foo_u32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar_u32,
   Polygon1_u32,
@@ -55,7 +59,11 @@ enum Foo_u32_Tag
   Slice4_u32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Foo_u32_Tag Foo_u32_Tag;
+#else
 typedef uint8_t Foo_u32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Slice3_Body_u32 {
@@ -91,9 +99,9 @@ struct Polygon_i32 {
 };
 
 enum Baz_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar2_i32,
   Polygon21_i32,
@@ -103,7 +111,11 @@ enum Baz_i32_Tag
   Slice24_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Baz_i32_Tag Baz_i32_Tag;
+#else
 typedef uint8_t Baz_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Slice23_Body_i32 {
@@ -137,16 +149,20 @@ union Baz_i32 {
 };
 
 enum Taz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar3,
   Taz1,
   Taz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Taz_Tag Taz_Tag;
+#else
 typedef uint8_t Taz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union Taz {
@@ -162,15 +178,19 @@ union Taz {
 };
 
 enum Tazz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar4,
   Taz2,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazz_Tag Tazz_Tag;
+#else
 typedef uint8_t Tazz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union Tazz {
@@ -182,15 +202,19 @@ union Tazz {
 };
 
 enum Tazzz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Bar5,
   Taz5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzz_Tag Tazzz_Tag;
+#else
 typedef uint8_t Tazzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union Tazzz {
@@ -202,15 +226,19 @@ union Tazzz {
 };
 
 enum Tazzzz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Taz6,
   Taz7,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Tazzzz_Tag Tazzzz_Tag;
+#else
 typedef uint8_t Tazzzz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union Tazzzz {
@@ -226,15 +254,19 @@ union Tazzzz {
 };
 
 enum Qux_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Qux1,
   Qux2,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Qux_Tag Qux_Tag;
+#else
 typedef uint8_t Qux_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union Qux {
diff --git a/tests/expectations/display_list.c b/tests/expectations/display_list.c
index 41a37d6a0..5d3b00690 100644
--- a/tests/expectations/display_list.c
+++ b/tests/expectations/display_list.c
@@ -17,12 +17,20 @@ typedef struct {
   uint8_t a;
 } Color;
 
-enum DisplayItem_Tag {
+enum DisplayItem_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Fill,
   Image,
   ClearScreen,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DisplayItem_Tag DisplayItem_Tag;
+#else
 typedef uint8_t DisplayItem_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   DisplayItem_Tag tag;
diff --git a/tests/expectations/display_list.compat.c b/tests/expectations/display_list.compat.c
index 79c7470dd..20bdcc722 100644
--- a/tests/expectations/display_list.compat.c
+++ b/tests/expectations/display_list.compat.c
@@ -18,16 +18,20 @@ typedef struct {
 } Color;
 
 enum DisplayItem_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Fill,
   Image,
   ClearScreen,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DisplayItem_Tag DisplayItem_Tag;
+#else
 typedef uint8_t DisplayItem_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/display_list_both.c b/tests/expectations/display_list_both.c
index 451eab73e..1b3856635 100644
--- a/tests/expectations/display_list_both.c
+++ b/tests/expectations/display_list_both.c
@@ -17,12 +17,20 @@ typedef struct Color {
   uint8_t a;
 } Color;
 
-enum DisplayItem_Tag {
+enum DisplayItem_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Fill,
   Image,
   ClearScreen,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DisplayItem_Tag DisplayItem_Tag;
+#else
 typedef uint8_t DisplayItem_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Fill_Body {
   DisplayItem_Tag tag;
diff --git a/tests/expectations/display_list_both.compat.c b/tests/expectations/display_list_both.compat.c
index 8dfd5223e..e0d44fc64 100644
--- a/tests/expectations/display_list_both.compat.c
+++ b/tests/expectations/display_list_both.compat.c
@@ -18,16 +18,20 @@ typedef struct Color {
 } Color;
 
 enum DisplayItem_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Fill,
   Image,
   ClearScreen,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DisplayItem_Tag DisplayItem_Tag;
+#else
 typedef uint8_t DisplayItem_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Fill_Body {
diff --git a/tests/expectations/display_list_tag.c b/tests/expectations/display_list_tag.c
index 78f53de3a..fa745e39f 100644
--- a/tests/expectations/display_list_tag.c
+++ b/tests/expectations/display_list_tag.c
@@ -17,12 +17,20 @@ struct Color {
   uint8_t a;
 };
 
-enum DisplayItem_Tag {
+enum DisplayItem_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Fill,
   Image,
   ClearScreen,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum DisplayItem_Tag DisplayItem_Tag;
+#else
 typedef uint8_t DisplayItem_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Fill_Body {
   DisplayItem_Tag tag;
diff --git a/tests/expectations/display_list_tag.compat.c b/tests/expectations/display_list_tag.compat.c
index ec7c2cd09..3cae38b21 100644
--- a/tests/expectations/display_list_tag.compat.c
+++ b/tests/expectations/display_list_tag.compat.c
@@ -18,16 +18,20 @@ struct Color {
 };
 
 enum DisplayItem_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Fill,
   Image,
   ClearScreen,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum DisplayItem_Tag DisplayItem_Tag;
+#else
 typedef uint8_t DisplayItem_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Fill_Body {
diff --git a/tests/expectations/enum.c b/tests/expectations/enum.c
index 0562a56a6..7cb12fca4 100644
--- a/tests/expectations/enum.c
+++ b/tests/expectations/enum.c
@@ -17,53 +17,101 @@ using Box = T*;
 #include <stdint.h>
 #include <stdlib.h>
 
-enum A {
+enum A
+#if __STDC_VERSION__ >= 202311L
+  : uint64_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   a1 = 0,
   a2 = 2,
   a3,
   a4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint64_t A;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum B {
+enum B
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   b1 = 0,
   b2 = 2,
   b3,
   b4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint32_t B;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint16_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   c1 = 0,
   c2 = 2,
   c3,
   c4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint16_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum D {
+enum D
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   d1 = 0,
   d2 = 2,
   d3,
   d4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum D D;
+#else
 typedef uint8_t D;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum E {
+enum E
+#if __STDC_VERSION__ >= 202311L
+  : uintptr_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   e1 = 0,
   e2 = 2,
   e3,
   e4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef uintptr_t E;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum F {
+enum F
+#if __STDC_VERSION__ >= 202311L
+  : intptr_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   f1 = 0,
   f2 = 2,
   f3,
   f4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F F;
+#else
 typedef intptr_t F;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef enum {
   l1,
@@ -72,12 +120,20 @@ typedef enum {
   l4,
 } L;
 
-enum M {
+enum M
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   m1 = -1,
   m2 = 0,
   m3 = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum M M;
+#else
 typedef int8_t M;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef enum {
   n1,
@@ -86,13 +142,21 @@ typedef enum {
   n4,
 } N;
 
-enum O {
+enum O
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   o1,
   o2,
   o3,
   o4,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum O O;
+#else
 typedef int8_t O;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct J J;
 
@@ -100,12 +164,20 @@ typedef struct K K;
 
 typedef struct Opaque Opaque;
 
-enum G_Tag {
+enum G_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum G_Tag G_Tag;
+#else
 typedef uint8_t G_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   G_Tag tag;
@@ -143,12 +215,20 @@ typedef struct {
   };
 } H;
 
-enum ExI_Tag {
+enum ExI_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   ExI_Foo,
   ExI_Bar,
   ExI_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum ExI_Tag ExI_Tag;
+#else
 typedef uint8_t ExI_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t x;
@@ -165,11 +245,19 @@ typedef struct {
   };
 } ExI;
 
-enum P_Tag {
+enum P_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   P0,
   P1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum P_Tag P_Tag;
+#else
 typedef uint8_t P_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   uint8_t _0;
diff --git a/tests/expectations/enum.compat.c b/tests/expectations/enum.compat.c
index 86cedb9f2..9c94ff704 100644
--- a/tests/expectations/enum.compat.c
+++ b/tests/expectations/enum.compat.c
@@ -18,9 +18,9 @@ using Box = T*;
 #include <stdlib.h>
 
 enum A
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint64_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   a1 = 0,
   a2 = 2,
@@ -28,13 +28,17 @@ enum A
   a4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint64_t A;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum B
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   b1 = 0,
   b2 = 2,
@@ -42,13 +46,17 @@ enum B
   b4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint32_t B;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint16_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   c1 = 0,
   c2 = 2,
@@ -56,13 +64,17 @@ enum C
   c4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint16_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum D
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   d1 = 0,
   d2 = 2,
@@ -70,13 +82,17 @@ enum D
   d4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum D D;
+#else
 typedef uint8_t D;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uintptr_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   e1 = 0,
   e2 = 2,
@@ -84,13 +100,17 @@ enum E
   e4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef uintptr_t E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum F
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : intptr_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   f1 = 0,
   f2 = 2,
@@ -98,7 +118,11 @@ enum F
   f4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F F;
+#else
 typedef intptr_t F;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef enum {
@@ -109,16 +133,20 @@ typedef enum {
 } L;
 
 enum M
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   m1 = -1,
   m2 = 0,
   m3 = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum M M;
+#else
 typedef int8_t M;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef enum {
@@ -129,9 +157,9 @@ typedef enum {
 } N;
 
 enum O
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   o1,
   o2,
@@ -139,7 +167,11 @@ enum O
   o4,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum O O;
+#else
 typedef int8_t O;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct J J;
@@ -149,16 +181,20 @@ typedef struct K K;
 typedef struct Opaque Opaque;
 
 enum G_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum G_Tag G_Tag;
+#else
 typedef uint8_t G_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -198,16 +234,20 @@ typedef struct {
 } H;
 
 enum ExI_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   ExI_Foo,
   ExI_Bar,
   ExI_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum ExI_Tag ExI_Tag;
+#else
 typedef uint8_t ExI_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -226,15 +266,19 @@ typedef struct {
 } ExI;
 
 enum P_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   P0,
   P1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum P_Tag P_Tag;
+#else
 typedef uint8_t P_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/enum_both.c b/tests/expectations/enum_both.c
index a0f88c13e..32916ebe2 100644
--- a/tests/expectations/enum_both.c
+++ b/tests/expectations/enum_both.c
@@ -17,53 +17,101 @@ using Box = T*;
 #include <stdint.h>
 #include <stdlib.h>
 
-enum A {
+enum A
+#if __STDC_VERSION__ >= 202311L
+  : uint64_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   a1 = 0,
   a2 = 2,
   a3,
   a4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint64_t A;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum B {
+enum B
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   b1 = 0,
   b2 = 2,
   b3,
   b4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint32_t B;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint16_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   c1 = 0,
   c2 = 2,
   c3,
   c4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint16_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum D {
+enum D
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   d1 = 0,
   d2 = 2,
   d3,
   d4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum D D;
+#else
 typedef uint8_t D;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum E {
+enum E
+#if __STDC_VERSION__ >= 202311L
+  : uintptr_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   e1 = 0,
   e2 = 2,
   e3,
   e4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef uintptr_t E;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum F {
+enum F
+#if __STDC_VERSION__ >= 202311L
+  : intptr_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   f1 = 0,
   f2 = 2,
   f3,
   f4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F F;
+#else
 typedef intptr_t F;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef enum L {
   l1,
@@ -72,12 +120,20 @@ typedef enum L {
   l4,
 } L;
 
-enum M {
+enum M
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   m1 = -1,
   m2 = 0,
   m3 = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum M M;
+#else
 typedef int8_t M;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef enum N {
   n1,
@@ -86,13 +142,21 @@ typedef enum N {
   n4,
 } N;
 
-enum O {
+enum O
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   o1,
   o2,
   o3,
   o4,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum O O;
+#else
 typedef int8_t O;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct J J;
 
@@ -100,12 +164,20 @@ typedef struct K K;
 
 typedef struct Opaque Opaque;
 
-enum G_Tag {
+enum G_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum G_Tag G_Tag;
+#else
 typedef uint8_t G_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Bar_Body {
   G_Tag tag;
@@ -143,12 +215,20 @@ typedef struct H {
   };
 } H;
 
-enum ExI_Tag {
+enum ExI_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   ExI_Foo,
   ExI_Bar,
   ExI_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum ExI_Tag ExI_Tag;
+#else
 typedef uint8_t ExI_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct ExI_Bar_Body {
   uint8_t x;
@@ -165,11 +245,19 @@ typedef struct ExI {
   };
 } ExI;
 
-enum P_Tag {
+enum P_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   P0,
   P1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum P_Tag P_Tag;
+#else
 typedef uint8_t P_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct P1_Body {
   uint8_t _0;
diff --git a/tests/expectations/enum_both.compat.c b/tests/expectations/enum_both.compat.c
index 35488252b..4adf18a20 100644
--- a/tests/expectations/enum_both.compat.c
+++ b/tests/expectations/enum_both.compat.c
@@ -18,9 +18,9 @@ using Box = T*;
 #include <stdlib.h>
 
 enum A
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint64_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   a1 = 0,
   a2 = 2,
@@ -28,13 +28,17 @@ enum A
   a4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint64_t A;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum B
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   b1 = 0,
   b2 = 2,
@@ -42,13 +46,17 @@ enum B
   b4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint32_t B;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint16_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   c1 = 0,
   c2 = 2,
@@ -56,13 +64,17 @@ enum C
   c4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint16_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum D
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   d1 = 0,
   d2 = 2,
@@ -70,13 +82,17 @@ enum D
   d4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum D D;
+#else
 typedef uint8_t D;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uintptr_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   e1 = 0,
   e2 = 2,
@@ -84,13 +100,17 @@ enum E
   e4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef uintptr_t E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum F
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : intptr_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   f1 = 0,
   f2 = 2,
@@ -98,7 +118,11 @@ enum F
   f4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F F;
+#else
 typedef intptr_t F;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef enum L {
@@ -109,16 +133,20 @@ typedef enum L {
 } L;
 
 enum M
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   m1 = -1,
   m2 = 0,
   m3 = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum M M;
+#else
 typedef int8_t M;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef enum N {
@@ -129,9 +157,9 @@ typedef enum N {
 } N;
 
 enum O
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   o1,
   o2,
@@ -139,7 +167,11 @@ enum O
   o4,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum O O;
+#else
 typedef int8_t O;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct J J;
@@ -149,16 +181,20 @@ typedef struct K K;
 typedef struct Opaque Opaque;
 
 enum G_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum G_Tag G_Tag;
+#else
 typedef uint8_t G_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Bar_Body {
@@ -198,16 +234,20 @@ typedef struct H {
 } H;
 
 enum ExI_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   ExI_Foo,
   ExI_Bar,
   ExI_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum ExI_Tag ExI_Tag;
+#else
 typedef uint8_t ExI_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct ExI_Bar_Body {
@@ -226,15 +266,19 @@ typedef struct ExI {
 } ExI;
 
 enum P_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   P0,
   P1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum P_Tag P_Tag;
+#else
 typedef uint8_t P_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct P1_Body {
diff --git a/tests/expectations/enum_discriminant.c b/tests/expectations/enum_discriminant.c
index 181dab159..9b7bfc00c 100644
--- a/tests/expectations/enum_discriminant.c
+++ b/tests/expectations/enum_discriminant.c
@@ -5,7 +5,11 @@
 
 #define FOURTY_FOUR 4
 
-enum E {
+enum E
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A = 1,
   B = -1,
   C = (1 + 2),
@@ -14,6 +18,10 @@ enum E {
   G = (int8_t)54,
   H = (int8_t)false,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef int8_t E;
+#endif // __STDC_VERSION__ >= 202311L
 
 void root(const E*);
diff --git a/tests/expectations/enum_discriminant.compat.c b/tests/expectations/enum_discriminant.compat.c
index 381ee4be1..427adb4d0 100644
--- a/tests/expectations/enum_discriminant.compat.c
+++ b/tests/expectations/enum_discriminant.compat.c
@@ -6,9 +6,9 @@
 #define FOURTY_FOUR 4
 
 enum E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A = 1,
   B = -1,
@@ -19,7 +19,11 @@ enum E
   H = (int8_t)false,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef int8_t E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 #ifdef __cplusplus
diff --git a/tests/expectations/enum_self.c b/tests/expectations/enum_self.c
index e383e76ab..9d7a3d4ff 100644
--- a/tests/expectations/enum_self.c
+++ b/tests/expectations/enum_self.c
@@ -7,12 +7,20 @@ typedef struct {
   const int32_t *something;
 } Foo_Bar;
 
-enum Bar_Tag {
+enum Bar_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Min,
   Max,
   Other,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   Bar_Tag tag;
diff --git a/tests/expectations/enum_self.compat.c b/tests/expectations/enum_self.compat.c
index 0b5472dc7..c358cae8f 100644
--- a/tests/expectations/enum_self.compat.c
+++ b/tests/expectations/enum_self.compat.c
@@ -8,16 +8,20 @@ typedef struct {
 } Foo_Bar;
 
 enum Bar_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Min,
   Max,
   Other,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
diff --git a/tests/expectations/enum_self_both.c b/tests/expectations/enum_self_both.c
index cc661216d..d06e76192 100644
--- a/tests/expectations/enum_self_both.c
+++ b/tests/expectations/enum_self_both.c
@@ -7,12 +7,20 @@ typedef struct Foo_Bar {
   const int32_t *something;
 } Foo_Bar;
 
-enum Bar_Tag {
+enum Bar_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Min,
   Max,
   Other,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union Bar {
   Bar_Tag tag;
diff --git a/tests/expectations/enum_self_both.compat.c b/tests/expectations/enum_self_both.compat.c
index 34d08e27f..dace203f9 100644
--- a/tests/expectations/enum_self_both.compat.c
+++ b/tests/expectations/enum_self_both.compat.c
@@ -8,16 +8,20 @@ typedef struct Foo_Bar {
 } Foo_Bar;
 
 enum Bar_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Min,
   Max,
   Other,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union Bar {
diff --git a/tests/expectations/enum_self_flags.c b/tests/expectations/enum_self_flags.c
index 7285d300b..81c717c06 100644
--- a/tests/expectations/enum_self_flags.c
+++ b/tests/expectations/enum_self_flags.c
@@ -22,7 +22,11 @@
  * Specifies which tracks(s) on the axis that the position-area span occupies.
  * Represented as 3 bits: start, center, end track.
  */
-enum PositionAreaTrack {
+enum PositionAreaTrack
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   /**
    * First track
    */
@@ -48,14 +52,22 @@ enum PositionAreaTrack {
    */
   SpanAll = 7,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum PositionAreaTrack PositionAreaTrack;
+#else
 typedef uint8_t PositionAreaTrack;
+#endif // __STDC_VERSION__ >= 202311L
 
 /**
  * A three-bit value that represents the axis in which position-area operates on.
  * Represented as 3 bits: axis type (physical or logical), direction type (physical or logical),
  * axis value.
  */
-enum PositionAreaAxis {
+enum PositionAreaAxis
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Horizontal = 0,
   Vertical = 1,
   X = 2,
@@ -63,7 +75,11 @@ enum PositionAreaAxis {
   Inline = 6,
   Block = 7,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum PositionAreaAxis PositionAreaAxis;
+#else
 typedef uint8_t PositionAreaAxis;
+#endif // __STDC_VERSION__ >= 202311L
 
 /**
  * Possible values for the `position-area` property's keywords.
@@ -71,7 +87,11 @@ typedef uint8_t PositionAreaAxis;
  * PositionAreaAxis and yyy is the PositionAreaTrack
  * https://drafts.csswg.org/css-anchor-position-1/#propdef-position-area
  */
-enum PositionAreaKeyword {
+enum PositionAreaKeyword
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   None = 0,
   Center = (uint8_t)PositionAreaTrack_Center,
   SpanAll = (uint8_t)PositionAreaTrack_SpanAll,
@@ -82,7 +102,11 @@ enum PositionAreaKeyword {
   Top = (((uint8_t)PositionAreaAxis_Vertical << AXIS_SHIFT) | (uint8_t)PositionAreaTrack_Start),
   Bottom = (((uint8_t)PositionAreaAxis_Vertical << AXIS_SHIFT) | (uint8_t)PositionAreaTrack_End),
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum PositionAreaKeyword PositionAreaKeyword;
+#else
 typedef uint8_t PositionAreaKeyword;
+#endif // __STDC_VERSION__ >= 202311L
 
 void root(PositionAreaKeyword, PositionAreaTrack, PositionAreaAxis);
 
diff --git a/tests/expectations/enum_self_flags.compat.c b/tests/expectations/enum_self_flags.compat.c
index 69fc0ae26..5d3737101 100644
--- a/tests/expectations/enum_self_flags.compat.c
+++ b/tests/expectations/enum_self_flags.compat.c
@@ -23,9 +23,9 @@
  * Represented as 3 bits: start, center, end track.
  */
 enum PositionAreaTrack
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   /**
    * First track
@@ -53,7 +53,11 @@ enum PositionAreaTrack
   SpanAll = 7,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum PositionAreaTrack PositionAreaTrack;
+#else
 typedef uint8_t PositionAreaTrack;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 /**
@@ -62,9 +66,9 @@ typedef uint8_t PositionAreaTrack;
  * axis value.
  */
 enum PositionAreaAxis
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Horizontal = 0,
   Vertical = 1,
@@ -74,7 +78,11 @@ enum PositionAreaAxis
   Block = 7,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum PositionAreaAxis PositionAreaAxis;
+#else
 typedef uint8_t PositionAreaAxis;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 /**
@@ -84,9 +92,9 @@ typedef uint8_t PositionAreaAxis;
  * https://drafts.csswg.org/css-anchor-position-1/#propdef-position-area
  */
 enum PositionAreaKeyword
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   None = 0,
   Center = (uint8_t)PositionAreaTrack_Center,
@@ -99,7 +107,11 @@ enum PositionAreaKeyword
   Bottom = (((uint8_t)PositionAreaAxis_Vertical << AXIS_SHIFT) | (uint8_t)PositionAreaTrack_End),
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum PositionAreaKeyword PositionAreaKeyword;
+#else
 typedef uint8_t PositionAreaKeyword;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 #ifdef __cplusplus
diff --git a/tests/expectations/enum_self_tag.c b/tests/expectations/enum_self_tag.c
index e09350337..a0dc47ef7 100644
--- a/tests/expectations/enum_self_tag.c
+++ b/tests/expectations/enum_self_tag.c
@@ -7,12 +7,20 @@ struct Foo_Bar {
   const int32_t *something;
 };
 
-enum Bar_Tag {
+enum Bar_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Min,
   Max,
   Other,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union Bar {
   Bar_Tag tag;
diff --git a/tests/expectations/enum_self_tag.compat.c b/tests/expectations/enum_self_tag.compat.c
index 77f5a3813..34541d0c4 100644
--- a/tests/expectations/enum_self_tag.compat.c
+++ b/tests/expectations/enum_self_tag.compat.c
@@ -8,16 +8,20 @@ struct Foo_Bar {
 };
 
 enum Bar_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Min,
   Max,
   Other,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Bar_Tag Bar_Tag;
+#else
 typedef uint8_t Bar_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union Bar {
diff --git a/tests/expectations/enum_tag.c b/tests/expectations/enum_tag.c
index a7f104688..f07faa324 100644
--- a/tests/expectations/enum_tag.c
+++ b/tests/expectations/enum_tag.c
@@ -17,53 +17,101 @@ using Box = T*;
 #include <stdint.h>
 #include <stdlib.h>
 
-enum A {
+enum A
+#if __STDC_VERSION__ >= 202311L
+  : uint64_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   a1 = 0,
   a2 = 2,
   a3,
   a4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint64_t A;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum B {
+enum B
+#if __STDC_VERSION__ >= 202311L
+  : uint32_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   b1 = 0,
   b2 = 2,
   b3,
   b4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint32_t B;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum C {
+enum C
+#if __STDC_VERSION__ >= 202311L
+  : uint16_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   c1 = 0,
   c2 = 2,
   c3,
   c4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint16_t C;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum D {
+enum D
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   d1 = 0,
   d2 = 2,
   d3,
   d4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum D D;
+#else
 typedef uint8_t D;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum E {
+enum E
+#if __STDC_VERSION__ >= 202311L
+  : uintptr_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   e1 = 0,
   e2 = 2,
   e3,
   e4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef uintptr_t E;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum F {
+enum F
+#if __STDC_VERSION__ >= 202311L
+  : intptr_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   f1 = 0,
   f2 = 2,
   f3,
   f4 = 5,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F F;
+#else
 typedef intptr_t F;
+#endif // __STDC_VERSION__ >= 202311L
 
 enum L {
   l1,
@@ -72,12 +120,20 @@ enum L {
   l4,
 };
 
-enum M {
+enum M
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   m1 = -1,
   m2 = 0,
   m3 = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum M M;
+#else
 typedef int8_t M;
+#endif // __STDC_VERSION__ >= 202311L
 
 enum N {
   n1,
@@ -86,13 +142,21 @@ enum N {
   n4,
 };
 
-enum O {
+enum O
+#if __STDC_VERSION__ >= 202311L
+  : int8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   o1,
   o2,
   o3,
   o4,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum O O;
+#else
 typedef int8_t O;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct J;
 
@@ -100,12 +164,20 @@ struct K;
 
 struct Opaque;
 
-enum G_Tag {
+enum G_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
   Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum G_Tag G_Tag;
+#else
 typedef uint8_t G_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Bar_Body {
   G_Tag tag;
@@ -143,12 +215,20 @@ struct H {
   };
 };
 
-enum ExI_Tag {
+enum ExI_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   ExI_Foo,
   ExI_Bar,
   ExI_Baz,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum ExI_Tag ExI_Tag;
+#else
 typedef uint8_t ExI_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct ExI_Bar_Body {
   uint8_t x;
@@ -165,11 +245,19 @@ struct ExI {
   };
 };
 
-enum P_Tag {
+enum P_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   P0,
   P1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum P_Tag P_Tag;
+#else
 typedef uint8_t P_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct P1_Body {
   uint8_t _0;
diff --git a/tests/expectations/enum_tag.compat.c b/tests/expectations/enum_tag.compat.c
index 9662a6529..9b04803fa 100644
--- a/tests/expectations/enum_tag.compat.c
+++ b/tests/expectations/enum_tag.compat.c
@@ -18,9 +18,9 @@ using Box = T*;
 #include <stdlib.h>
 
 enum A
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint64_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   a1 = 0,
   a2 = 2,
@@ -28,13 +28,17 @@ enum A
   a4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint64_t A;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum B
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint32_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   b1 = 0,
   b2 = 2,
@@ -42,13 +46,17 @@ enum B
   b4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint32_t B;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum C
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint16_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   c1 = 0,
   c2 = 2,
@@ -56,13 +64,17 @@ enum C
   c4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C C;
+#else
 typedef uint16_t C;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum D
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   d1 = 0,
   d2 = 2,
@@ -70,13 +82,17 @@ enum D
   d4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum D D;
+#else
 typedef uint8_t D;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uintptr_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   e1 = 0,
   e2 = 2,
@@ -84,13 +100,17 @@ enum E
   e4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E E;
+#else
 typedef uintptr_t E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum F
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : intptr_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   f1 = 0,
   f2 = 2,
@@ -98,7 +118,11 @@ enum F
   f4 = 5,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F F;
+#else
 typedef intptr_t F;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum L {
@@ -109,16 +133,20 @@ enum L {
 };
 
 enum M
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   m1 = -1,
   m2 = 0,
   m3 = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum M M;
+#else
 typedef int8_t M;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum N {
@@ -129,9 +157,9 @@ enum N {
 };
 
 enum O
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : int8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   o1,
   o2,
@@ -139,7 +167,11 @@ enum O
   o4,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum O O;
+#else
 typedef int8_t O;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct J;
@@ -149,16 +181,20 @@ struct K;
 struct Opaque;
 
 enum G_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
   Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum G_Tag G_Tag;
+#else
 typedef uint8_t G_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Bar_Body {
@@ -198,16 +234,20 @@ struct H {
 };
 
 enum ExI_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   ExI_Foo,
   ExI_Bar,
   ExI_Baz,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum ExI_Tag ExI_Tag;
+#else
 typedef uint8_t ExI_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct ExI_Bar_Body {
@@ -226,15 +266,19 @@ struct ExI {
 };
 
 enum P_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   P0,
   P1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum P_Tag P_Tag;
+#else
 typedef uint8_t P_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct P1_Body {
diff --git a/tests/expectations/item_types.c b/tests/expectations/item_types.c
index 3d033a862..1cdb09293 100644
--- a/tests/expectations/item_types.c
+++ b/tests/expectations/item_types.c
@@ -3,8 +3,16 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum OnlyThisShouldBeGenerated {
+enum OnlyThisShouldBeGenerated
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum OnlyThisShouldBeGenerated OnlyThisShouldBeGenerated;
+#else
 typedef uint8_t OnlyThisShouldBeGenerated;
+#endif // __STDC_VERSION__ >= 202311L
diff --git a/tests/expectations/item_types.compat.c b/tests/expectations/item_types.compat.c
index 6eab9e04c..88a67dd31 100644
--- a/tests/expectations/item_types.compat.c
+++ b/tests/expectations/item_types.compat.c
@@ -4,13 +4,17 @@
 #include <stdlib.h>
 
 enum OnlyThisShouldBeGenerated
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum OnlyThisShouldBeGenerated OnlyThisShouldBeGenerated;
+#else
 typedef uint8_t OnlyThisShouldBeGenerated;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
diff --git a/tests/expectations/item_types_renamed.c b/tests/expectations/item_types_renamed.c
index ffa3eaa56..8b565918a 100644
--- a/tests/expectations/item_types_renamed.c
+++ b/tests/expectations/item_types_renamed.c
@@ -3,8 +3,16 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum StyleOnlyThisShouldBeGenerated {
+enum StyleOnlyThisShouldBeGenerated
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo,
   Bar,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleOnlyThisShouldBeGenerated StyleOnlyThisShouldBeGenerated;
+#else
 typedef uint8_t StyleOnlyThisShouldBeGenerated;
+#endif // __STDC_VERSION__ >= 202311L
diff --git a/tests/expectations/item_types_renamed.compat.c b/tests/expectations/item_types_renamed.compat.c
index 4912fa78e..5937055e4 100644
--- a/tests/expectations/item_types_renamed.compat.c
+++ b/tests/expectations/item_types_renamed.compat.c
@@ -4,13 +4,17 @@
 #include <stdlib.h>
 
 enum StyleOnlyThisShouldBeGenerated
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo,
   Bar,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleOnlyThisShouldBeGenerated StyleOnlyThisShouldBeGenerated;
+#else
 typedef uint8_t StyleOnlyThisShouldBeGenerated;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
diff --git a/tests/expectations/must_use.c b/tests/expectations/must_use.c
index 1ecad7294..40550c1a4 100644
--- a/tests/expectations/must_use.c
+++ b/tests/expectations/must_use.c
@@ -8,11 +8,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum MaybeOwnedPtr_i32_Tag {
+enum MaybeOwnedPtr_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Owned_i32,
   None_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum MaybeOwnedPtr_i32_Tag MaybeOwnedPtr_i32_Tag;
+#else
 typedef uint8_t MaybeOwnedPtr_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct MUST_USE_STRUCT {
   MaybeOwnedPtr_i32_Tag tag;
diff --git a/tests/expectations/must_use.compat.c b/tests/expectations/must_use.compat.c
index b6fd17247..4597116b1 100644
--- a/tests/expectations/must_use.compat.c
+++ b/tests/expectations/must_use.compat.c
@@ -9,15 +9,19 @@
 #include <stdlib.h>
 
 enum MaybeOwnedPtr_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Owned_i32,
   None_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum MaybeOwnedPtr_i32_Tag MaybeOwnedPtr_i32_Tag;
+#else
 typedef uint8_t MaybeOwnedPtr_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct MUST_USE_STRUCT {
diff --git a/tests/expectations/must_use_both.c b/tests/expectations/must_use_both.c
index c55ce31c0..e2777f49c 100644
--- a/tests/expectations/must_use_both.c
+++ b/tests/expectations/must_use_both.c
@@ -8,11 +8,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum MaybeOwnedPtr_i32_Tag {
+enum MaybeOwnedPtr_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Owned_i32,
   None_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum MaybeOwnedPtr_i32_Tag MaybeOwnedPtr_i32_Tag;
+#else
 typedef uint8_t MaybeOwnedPtr_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct MUST_USE_STRUCT MaybeOwnedPtr_i32 {
   MaybeOwnedPtr_i32_Tag tag;
diff --git a/tests/expectations/must_use_both.compat.c b/tests/expectations/must_use_both.compat.c
index f56e8f03b..ec18d064e 100644
--- a/tests/expectations/must_use_both.compat.c
+++ b/tests/expectations/must_use_both.compat.c
@@ -9,15 +9,19 @@
 #include <stdlib.h>
 
 enum MaybeOwnedPtr_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Owned_i32,
   None_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum MaybeOwnedPtr_i32_Tag MaybeOwnedPtr_i32_Tag;
+#else
 typedef uint8_t MaybeOwnedPtr_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct MUST_USE_STRUCT MaybeOwnedPtr_i32 {
diff --git a/tests/expectations/must_use_tag.c b/tests/expectations/must_use_tag.c
index 16c3d34a5..4d5505fba 100644
--- a/tests/expectations/must_use_tag.c
+++ b/tests/expectations/must_use_tag.c
@@ -8,11 +8,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum MaybeOwnedPtr_i32_Tag {
+enum MaybeOwnedPtr_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Owned_i32,
   None_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum MaybeOwnedPtr_i32_Tag MaybeOwnedPtr_i32_Tag;
+#else
 typedef uint8_t MaybeOwnedPtr_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct MUST_USE_STRUCT MaybeOwnedPtr_i32 {
   MaybeOwnedPtr_i32_Tag tag;
diff --git a/tests/expectations/must_use_tag.compat.c b/tests/expectations/must_use_tag.compat.c
index 7aa48cefc..7cdbbfa5e 100644
--- a/tests/expectations/must_use_tag.compat.c
+++ b/tests/expectations/must_use_tag.compat.c
@@ -9,15 +9,19 @@
 #include <stdlib.h>
 
 enum MaybeOwnedPtr_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Owned_i32,
   None_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum MaybeOwnedPtr_i32_Tag MaybeOwnedPtr_i32_Tag;
+#else
 typedef uint8_t MaybeOwnedPtr_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct MUST_USE_STRUCT MaybeOwnedPtr_i32 {
diff --git a/tests/expectations/prefix.c b/tests/expectations/prefix.c
index 4ef6a7123..ee187e5ba 100644
--- a/tests/expectations/prefix.c
+++ b/tests/expectations/prefix.c
@@ -13,12 +13,20 @@ typedef int32_t PREFIX_NamedLenArray[PREFIX_LEN];
 
 typedef int32_t PREFIX_ValuedLenArray[22];
 
-enum PREFIX_AbsoluteFontWeight_Tag {
+enum PREFIX_AbsoluteFontWeight_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Weight,
   Normal,
   Bold,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum PREFIX_AbsoluteFontWeight_Tag PREFIX_AbsoluteFontWeight_Tag;
+#else
 typedef uint8_t PREFIX_AbsoluteFontWeight_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   PREFIX_AbsoluteFontWeight_Tag tag;
diff --git a/tests/expectations/prefix.compat.c b/tests/expectations/prefix.compat.c
index a37a15a0a..6e15e861e 100644
--- a/tests/expectations/prefix.compat.c
+++ b/tests/expectations/prefix.compat.c
@@ -14,16 +14,20 @@ typedef int32_t PREFIX_NamedLenArray[PREFIX_LEN];
 typedef int32_t PREFIX_ValuedLenArray[22];
 
 enum PREFIX_AbsoluteFontWeight_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Weight,
   Normal,
   Bold,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum PREFIX_AbsoluteFontWeight_Tag PREFIX_AbsoluteFontWeight_Tag;
+#else
 typedef uint8_t PREFIX_AbsoluteFontWeight_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
diff --git a/tests/expectations/prefix_both.c b/tests/expectations/prefix_both.c
index 1eb9f74cf..57cca6233 100644
--- a/tests/expectations/prefix_both.c
+++ b/tests/expectations/prefix_both.c
@@ -13,12 +13,20 @@ typedef int32_t PREFIX_NamedLenArray[PREFIX_LEN];
 
 typedef int32_t PREFIX_ValuedLenArray[22];
 
-enum PREFIX_AbsoluteFontWeight_Tag {
+enum PREFIX_AbsoluteFontWeight_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Weight,
   Normal,
   Bold,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum PREFIX_AbsoluteFontWeight_Tag PREFIX_AbsoluteFontWeight_Tag;
+#else
 typedef uint8_t PREFIX_AbsoluteFontWeight_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union PREFIX_AbsoluteFontWeight {
   PREFIX_AbsoluteFontWeight_Tag tag;
diff --git a/tests/expectations/prefix_both.compat.c b/tests/expectations/prefix_both.compat.c
index 1b6475c35..30f2c6652 100644
--- a/tests/expectations/prefix_both.compat.c
+++ b/tests/expectations/prefix_both.compat.c
@@ -14,16 +14,20 @@ typedef int32_t PREFIX_NamedLenArray[PREFIX_LEN];
 typedef int32_t PREFIX_ValuedLenArray[22];
 
 enum PREFIX_AbsoluteFontWeight_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Weight,
   Normal,
   Bold,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum PREFIX_AbsoluteFontWeight_Tag PREFIX_AbsoluteFontWeight_Tag;
+#else
 typedef uint8_t PREFIX_AbsoluteFontWeight_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union PREFIX_AbsoluteFontWeight {
diff --git a/tests/expectations/prefix_tag.c b/tests/expectations/prefix_tag.c
index d23d556f7..7e931ef4c 100644
--- a/tests/expectations/prefix_tag.c
+++ b/tests/expectations/prefix_tag.c
@@ -13,12 +13,20 @@ typedef int32_t PREFIX_NamedLenArray[PREFIX_LEN];
 
 typedef int32_t PREFIX_ValuedLenArray[22];
 
-enum PREFIX_AbsoluteFontWeight_Tag {
+enum PREFIX_AbsoluteFontWeight_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Weight,
   Normal,
   Bold,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum PREFIX_AbsoluteFontWeight_Tag PREFIX_AbsoluteFontWeight_Tag;
+#else
 typedef uint8_t PREFIX_AbsoluteFontWeight_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union PREFIX_AbsoluteFontWeight {
   PREFIX_AbsoluteFontWeight_Tag tag;
diff --git a/tests/expectations/prefix_tag.compat.c b/tests/expectations/prefix_tag.compat.c
index e300cdad1..6ed0ea2e9 100644
--- a/tests/expectations/prefix_tag.compat.c
+++ b/tests/expectations/prefix_tag.compat.c
@@ -14,16 +14,20 @@ typedef int32_t PREFIX_NamedLenArray[PREFIX_LEN];
 typedef int32_t PREFIX_ValuedLenArray[22];
 
 enum PREFIX_AbsoluteFontWeight_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Weight,
   Normal,
   Bold,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum PREFIX_AbsoluteFontWeight_Tag PREFIX_AbsoluteFontWeight_Tag;
+#else
 typedef uint8_t PREFIX_AbsoluteFontWeight_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union PREFIX_AbsoluteFontWeight {
diff --git a/tests/expectations/raw_ident.c b/tests/expectations/raw_ident.c
index 4b6ccd982..45a441e35 100644
--- a/tests/expectations/raw_ident.c
+++ b/tests/expectations/raw_ident.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Enum {
+enum Enum
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   a,
   b,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Enum Enum;
+#else
 typedef uint8_t Enum;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   Enum field;
diff --git a/tests/expectations/raw_ident.compat.c b/tests/expectations/raw_ident.compat.c
index a8d149071..e1acba769 100644
--- a/tests/expectations/raw_ident.compat.c
+++ b/tests/expectations/raw_ident.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Enum
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   a,
   b,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Enum Enum;
+#else
 typedef uint8_t Enum;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/raw_ident_both.c b/tests/expectations/raw_ident_both.c
index fc302c327..a630c664d 100644
--- a/tests/expectations/raw_ident_both.c
+++ b/tests/expectations/raw_ident_both.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Enum {
+enum Enum
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   a,
   b,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Enum Enum;
+#else
 typedef uint8_t Enum;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct Struct {
   Enum field;
diff --git a/tests/expectations/raw_ident_both.compat.c b/tests/expectations/raw_ident_both.compat.c
index 07f66e894..19df639c8 100644
--- a/tests/expectations/raw_ident_both.compat.c
+++ b/tests/expectations/raw_ident_both.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Enum
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   a,
   b,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Enum Enum;
+#else
 typedef uint8_t Enum;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct Struct {
diff --git a/tests/expectations/raw_ident_tag.c b/tests/expectations/raw_ident_tag.c
index ae77cf043..0e424e1d8 100644
--- a/tests/expectations/raw_ident_tag.c
+++ b/tests/expectations/raw_ident_tag.c
@@ -3,11 +3,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum Enum {
+enum Enum
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   a,
   b,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum Enum Enum;
+#else
 typedef uint8_t Enum;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct Struct {
   Enum field;
diff --git a/tests/expectations/raw_ident_tag.compat.c b/tests/expectations/raw_ident_tag.compat.c
index afa24586d..239430378 100644
--- a/tests/expectations/raw_ident_tag.compat.c
+++ b/tests/expectations/raw_ident_tag.compat.c
@@ -4,15 +4,19 @@
 #include <stdlib.h>
 
 enum Enum
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   a,
   b,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum Enum Enum;
+#else
 typedef uint8_t Enum;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct Struct {
diff --git a/tests/expectations/rename.c b/tests/expectations/rename.c
index 738907d4e..32633a798 100644
--- a/tests/expectations/rename.c
+++ b/tests/expectations/rename.c
@@ -5,11 +5,19 @@
 
 #define C_H 10
 
-enum C_E {
+enum C_E
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   x = 0,
   y = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_E C_E;
+#else
 typedef uint8_t C_E;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct C_A C_A;
 
diff --git a/tests/expectations/rename.compat.c b/tests/expectations/rename.compat.c
index 75f6644e0..4ce79c36c 100644
--- a/tests/expectations/rename.compat.c
+++ b/tests/expectations/rename.compat.c
@@ -6,15 +6,19 @@
 #define C_H 10
 
 enum C_E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   x = 0,
   y = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_E C_E;
+#else
 typedef uint8_t C_E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct C_A C_A;
diff --git a/tests/expectations/rename_both.c b/tests/expectations/rename_both.c
index 6c6e9a5ab..9385ce5d7 100644
--- a/tests/expectations/rename_both.c
+++ b/tests/expectations/rename_both.c
@@ -5,11 +5,19 @@
 
 #define C_H 10
 
-enum C_E {
+enum C_E
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   x = 0,
   y = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_E C_E;
+#else
 typedef uint8_t C_E;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct C_A C_A;
 
diff --git a/tests/expectations/rename_both.compat.c b/tests/expectations/rename_both.compat.c
index 9361e68b1..4a5d0f5e6 100644
--- a/tests/expectations/rename_both.compat.c
+++ b/tests/expectations/rename_both.compat.c
@@ -6,15 +6,19 @@
 #define C_H 10
 
 enum C_E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   x = 0,
   y = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_E C_E;
+#else
 typedef uint8_t C_E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct C_A C_A;
diff --git a/tests/expectations/rename_tag.c b/tests/expectations/rename_tag.c
index ca127187b..b88879db6 100644
--- a/tests/expectations/rename_tag.c
+++ b/tests/expectations/rename_tag.c
@@ -5,11 +5,19 @@
 
 #define C_H 10
 
-enum C_E {
+enum C_E
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   x = 0,
   y = 1,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_E C_E;
+#else
 typedef uint8_t C_E;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct C_A;
 
diff --git a/tests/expectations/rename_tag.compat.c b/tests/expectations/rename_tag.compat.c
index e952b49eb..f99aa56a9 100644
--- a/tests/expectations/rename_tag.compat.c
+++ b/tests/expectations/rename_tag.compat.c
@@ -6,15 +6,19 @@
 #define C_H 10
 
 enum C_E
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   x = 0,
   y = 1,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_E C_E;
+#else
 typedef uint8_t C_E;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct C_A;
diff --git a/tests/expectations/reserved.c b/tests/expectations/reserved.c
index d4c81c60d..4c050b173 100644
--- a/tests/expectations/reserved.c
+++ b/tests/expectations/reserved.c
@@ -13,10 +13,18 @@ typedef struct {
   float float_;
 } B;
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   D,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   int32_t namespace_;
@@ -30,11 +38,19 @@ typedef struct {
   };
 } C;
 
-enum E_Tag {
+enum E_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Double,
   Float,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E_Tag E_Tag;
+#else
 typedef uint8_t E_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   E_Tag tag;
@@ -48,11 +64,19 @@ typedef struct {
   };
 } E;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   double_,
   float_,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   F_Tag tag;
diff --git a/tests/expectations/reserved.compat.c b/tests/expectations/reserved.compat.c
index ecdade3c9..04386e527 100644
--- a/tests/expectations/reserved.compat.c
+++ b/tests/expectations/reserved.compat.c
@@ -14,14 +14,18 @@ typedef struct {
 } B;
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   D,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -37,15 +41,19 @@ typedef struct {
 } C;
 
 enum E_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Double,
   Float,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E_Tag E_Tag;
+#else
 typedef uint8_t E_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -61,15 +69,19 @@ typedef struct {
 } E;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   double_,
   float_,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/reserved_both.c b/tests/expectations/reserved_both.c
index ce7d6e427..be88d9460 100644
--- a/tests/expectations/reserved_both.c
+++ b/tests/expectations/reserved_both.c
@@ -13,10 +13,18 @@ typedef struct B {
   float float_;
 } B;
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   D,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct D_Body {
   int32_t namespace_;
@@ -30,11 +38,19 @@ typedef struct C {
   };
 } C;
 
-enum E_Tag {
+enum E_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Double,
   Float,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E_Tag E_Tag;
+#else
 typedef uint8_t E_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct E {
   E_Tag tag;
@@ -48,11 +64,19 @@ typedef struct E {
   };
 } E;
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   double_,
   float_,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct F {
   F_Tag tag;
diff --git a/tests/expectations/reserved_both.compat.c b/tests/expectations/reserved_both.compat.c
index 702a1b7e8..2c5c0a0e0 100644
--- a/tests/expectations/reserved_both.compat.c
+++ b/tests/expectations/reserved_both.compat.c
@@ -14,14 +14,18 @@ typedef struct B {
 } B;
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   D,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct D_Body {
@@ -37,15 +41,19 @@ typedef struct C {
 } C;
 
 enum E_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Double,
   Float,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E_Tag E_Tag;
+#else
 typedef uint8_t E_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct E {
@@ -61,15 +69,19 @@ typedef struct E {
 } E;
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   double_,
   float_,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct F {
diff --git a/tests/expectations/reserved_tag.c b/tests/expectations/reserved_tag.c
index d81f89e87..65f83d848 100644
--- a/tests/expectations/reserved_tag.c
+++ b/tests/expectations/reserved_tag.c
@@ -13,10 +13,18 @@ struct B {
   float float_;
 };
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   D,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct D_Body {
   int32_t namespace_;
@@ -30,11 +38,19 @@ struct C {
   };
 };
 
-enum E_Tag {
+enum E_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Double,
   Float,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum E_Tag E_Tag;
+#else
 typedef uint8_t E_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct E {
   E_Tag tag;
@@ -48,11 +64,19 @@ struct E {
   };
 };
 
-enum F_Tag {
+enum F_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   double_,
   float_,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct F {
   F_Tag tag;
diff --git a/tests/expectations/reserved_tag.compat.c b/tests/expectations/reserved_tag.compat.c
index 0ce3ee237..b0238aef1 100644
--- a/tests/expectations/reserved_tag.compat.c
+++ b/tests/expectations/reserved_tag.compat.c
@@ -14,14 +14,18 @@ struct B {
 };
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   D,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct D_Body {
@@ -37,15 +41,19 @@ struct C {
 };
 
 enum E_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Double,
   Float,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum E_Tag E_Tag;
+#else
 typedef uint8_t E_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct E {
@@ -61,15 +69,19 @@ struct E {
 };
 
 enum F_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   double_,
   float_,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum F_Tag F_Tag;
+#else
 typedef uint8_t F_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct F {
diff --git a/tests/expectations/sentinel.c b/tests/expectations/sentinel.c
index 27057f3aa..108c333e7 100644
--- a/tests/expectations/sentinel.c
+++ b/tests/expectations/sentinel.c
@@ -3,7 +3,11 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum A {
+enum A
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A_A1,
   A_A2,
   A_A3,
@@ -12,9 +16,17 @@ enum A {
    */
   A_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint8_t A;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum B {
+enum B
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   B_B1,
   B_B2,
   B_B3,
@@ -23,9 +35,17 @@ enum B {
    */
   B_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint8_t B;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C_C1,
   C_C2,
   C_C3,
@@ -34,7 +54,11 @@ enum C_Tag {
    */
   C_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   C_Tag tag;
diff --git a/tests/expectations/sentinel.compat.c b/tests/expectations/sentinel.compat.c
index 124b06e8c..ab3e60a7c 100644
--- a/tests/expectations/sentinel.compat.c
+++ b/tests/expectations/sentinel.compat.c
@@ -4,9 +4,9 @@
 #include <stdlib.h>
 
 enum A
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A_A1,
   A_A2,
@@ -17,13 +17,17 @@ enum A
   A_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint8_t A;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum B
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   B_B1,
   B_B2,
@@ -34,13 +38,17 @@ enum B
   B_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint8_t B;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C_C1,
   C_C2,
@@ -51,7 +59,11 @@ enum C_Tag
   C_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/sentinel_both.c b/tests/expectations/sentinel_both.c
index 0ffb5afe6..ad4a433b7 100644
--- a/tests/expectations/sentinel_both.c
+++ b/tests/expectations/sentinel_both.c
@@ -3,7 +3,11 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum A {
+enum A
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A_A1,
   A_A2,
   A_A3,
@@ -12,9 +16,17 @@ enum A {
    */
   A_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint8_t A;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum B {
+enum B
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   B_B1,
   B_B2,
   B_B3,
@@ -23,9 +35,17 @@ enum B {
    */
   B_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint8_t B;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C_C1,
   C_C2,
   C_C3,
@@ -34,7 +54,11 @@ enum C_Tag {
    */
   C_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct C_C1_Body {
   C_Tag tag;
diff --git a/tests/expectations/sentinel_both.compat.c b/tests/expectations/sentinel_both.compat.c
index ac26146db..e2e7f50c9 100644
--- a/tests/expectations/sentinel_both.compat.c
+++ b/tests/expectations/sentinel_both.compat.c
@@ -4,9 +4,9 @@
 #include <stdlib.h>
 
 enum A
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A_A1,
   A_A2,
@@ -17,13 +17,17 @@ enum A
   A_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint8_t A;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum B
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   B_B1,
   B_B2,
@@ -34,13 +38,17 @@ enum B
   B_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint8_t B;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C_C1,
   C_C2,
@@ -51,7 +59,11 @@ enum C_Tag
   C_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct C_C1_Body {
diff --git a/tests/expectations/sentinel_tag.c b/tests/expectations/sentinel_tag.c
index 8e376e634..6b9b5d1b2 100644
--- a/tests/expectations/sentinel_tag.c
+++ b/tests/expectations/sentinel_tag.c
@@ -3,7 +3,11 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum A {
+enum A
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   A_A1,
   A_A2,
   A_A3,
@@ -12,9 +16,17 @@ enum A {
    */
   A_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint8_t A;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum B {
+enum B
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   B_B1,
   B_B2,
   B_B3,
@@ -23,9 +35,17 @@ enum B {
    */
   B_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint8_t B;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum C_Tag {
+enum C_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   C_C1,
   C_C2,
   C_C3,
@@ -34,7 +54,11 @@ enum C_Tag {
    */
   C_Sentinel,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct C_C1_Body {
   C_Tag tag;
diff --git a/tests/expectations/sentinel_tag.compat.c b/tests/expectations/sentinel_tag.compat.c
index e4dac92b0..52526c474 100644
--- a/tests/expectations/sentinel_tag.compat.c
+++ b/tests/expectations/sentinel_tag.compat.c
@@ -4,9 +4,9 @@
 #include <stdlib.h>
 
 enum A
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   A_A1,
   A_A2,
@@ -17,13 +17,17 @@ enum A
   A_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum A A;
+#else
 typedef uint8_t A;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum B
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   B_B1,
   B_B2,
@@ -34,13 +38,17 @@ enum B
   B_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum B B;
+#else
 typedef uint8_t B;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum C_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   C_C1,
   C_C2,
@@ -51,7 +59,11 @@ enum C_Tag
   C_Sentinel,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum C_Tag C_Tag;
+#else
 typedef uint8_t C_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct C_C1_Body {
diff --git a/tests/expectations/size_types.c b/tests/expectations/size_types.c
index 5ed52f566..db94a4276 100644
--- a/tests/expectations/size_types.c
+++ b/tests/expectations/size_types.c
@@ -4,15 +4,31 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-enum UE {
+enum UE
+#if __STDC_VERSION__ >= 202311L
+  : size_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   UV,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum UE UE;
+#else
 typedef size_t UE;
+#endif // __STDC_VERSION__ >= 202311L
 
-enum IE {
+enum IE
+#if __STDC_VERSION__ >= 202311L
+  : ptrdiff_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   IV,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum IE IE;
+#else
 typedef ptrdiff_t IE;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef size_t Usize;
 
diff --git a/tests/expectations/size_types.compat.c b/tests/expectations/size_types.compat.c
index 58428612c..f13d6cece 100644
--- a/tests/expectations/size_types.compat.c
+++ b/tests/expectations/size_types.compat.c
@@ -5,25 +5,33 @@
 #include <stdlib.h>
 
 enum UE
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : size_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   UV,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum UE UE;
+#else
 typedef size_t UE;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 enum IE
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : ptrdiff_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   IV,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum IE IE;
+#else
 typedef ptrdiff_t IE;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef size_t Usize;
diff --git a/tests/expectations/transform_op.c b/tests/expectations/transform_op.c
index 640ba5501..5286bc99d 100644
--- a/tests/expectations/transform_op.c
+++ b/tests/expectations/transform_op.c
@@ -13,13 +13,21 @@ typedef struct {
   float y;
 } StylePoint_f32;
 
-enum StyleFoo_i32_Tag {
+enum StyleFoo_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo_i32,
   Bar_i32,
   Baz_i32,
   Bazz_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleFoo_i32_Tag StyleFoo_i32_Tag;
+#else
 typedef uint8_t StyleFoo_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   StyleFoo_i32_Tag tag;
@@ -100,12 +108,20 @@ typedef struct {
   };
 } StyleBar_u32;
 
-enum StyleBaz_Tag {
+enum StyleBaz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Baz1,
   Baz2,
   Baz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleBaz_Tag StyleBaz_Tag;
+#else
 typedef uint8_t StyleBaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union {
   StyleBaz_Tag tag;
@@ -119,12 +135,20 @@ typedef union {
   };
 } StyleBaz;
 
-enum StyleTaz_Tag {
+enum StyleTaz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Taz1,
   Taz2,
   Taz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleTaz_Tag StyleTaz_Tag;
+#else
 typedef uint8_t StyleTaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct {
   StyleTaz_Tag tag;
diff --git a/tests/expectations/transform_op.compat.c b/tests/expectations/transform_op.compat.c
index 8608b43b0..35a635561 100644
--- a/tests/expectations/transform_op.compat.c
+++ b/tests/expectations/transform_op.compat.c
@@ -14,9 +14,9 @@ typedef struct {
 } StylePoint_f32;
 
 enum StyleFoo_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo_i32,
   Bar_i32,
@@ -24,7 +24,11 @@ enum StyleFoo_i32_Tag
   Bazz_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleFoo_i32_Tag StyleFoo_i32_Tag;
+#else
 typedef uint8_t StyleFoo_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
@@ -107,16 +111,20 @@ typedef struct {
 } StyleBar_u32;
 
 enum StyleBaz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Baz1,
   Baz2,
   Baz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleBaz_Tag StyleBaz_Tag;
+#else
 typedef uint8_t StyleBaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union {
@@ -132,16 +140,20 @@ typedef union {
 } StyleBaz;
 
 enum StyleTaz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Taz1,
   Taz2,
   Taz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleTaz_Tag StyleTaz_Tag;
+#else
 typedef uint8_t StyleTaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct {
diff --git a/tests/expectations/transform_op_both.c b/tests/expectations/transform_op_both.c
index e9605c39a..8f93b78d5 100644
--- a/tests/expectations/transform_op_both.c
+++ b/tests/expectations/transform_op_both.c
@@ -13,13 +13,21 @@ typedef struct StylePoint_f32 {
   float y;
 } StylePoint_f32;
 
-enum StyleFoo_i32_Tag {
+enum StyleFoo_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo_i32,
   Bar_i32,
   Baz_i32,
   Bazz_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleFoo_i32_Tag StyleFoo_i32_Tag;
+#else
 typedef uint8_t StyleFoo_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct StyleFoo_Body_i32 {
   StyleFoo_i32_Tag tag;
@@ -100,12 +108,20 @@ typedef struct StyleBar_u32 {
   };
 } StyleBar_u32;
 
-enum StyleBaz_Tag {
+enum StyleBaz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Baz1,
   Baz2,
   Baz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleBaz_Tag StyleBaz_Tag;
+#else
 typedef uint8_t StyleBaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef union StyleBaz {
   StyleBaz_Tag tag;
@@ -119,12 +135,20 @@ typedef union StyleBaz {
   };
 } StyleBaz;
 
-enum StyleTaz_Tag {
+enum StyleTaz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Taz1,
   Taz2,
   Taz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleTaz_Tag StyleTaz_Tag;
+#else
 typedef uint8_t StyleTaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 typedef struct StyleTaz {
   StyleTaz_Tag tag;
diff --git a/tests/expectations/transform_op_both.compat.c b/tests/expectations/transform_op_both.compat.c
index d4ab94d3b..a70b16f62 100644
--- a/tests/expectations/transform_op_both.compat.c
+++ b/tests/expectations/transform_op_both.compat.c
@@ -14,9 +14,9 @@ typedef struct StylePoint_f32 {
 } StylePoint_f32;
 
 enum StyleFoo_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo_i32,
   Bar_i32,
@@ -24,7 +24,11 @@ enum StyleFoo_i32_Tag
   Bazz_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleFoo_i32_Tag StyleFoo_i32_Tag;
+#else
 typedef uint8_t StyleFoo_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct StyleFoo_Body_i32 {
@@ -107,16 +111,20 @@ typedef struct StyleBar_u32 {
 } StyleBar_u32;
 
 enum StyleBaz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Baz1,
   Baz2,
   Baz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleBaz_Tag StyleBaz_Tag;
+#else
 typedef uint8_t StyleBaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef union StyleBaz {
@@ -132,16 +140,20 @@ typedef union StyleBaz {
 } StyleBaz;
 
 enum StyleTaz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Taz1,
   Taz2,
   Taz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleTaz_Tag StyleTaz_Tag;
+#else
 typedef uint8_t StyleTaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 typedef struct StyleTaz {
diff --git a/tests/expectations/transform_op_tag.c b/tests/expectations/transform_op_tag.c
index a97d4ae34..69b1747a5 100644
--- a/tests/expectations/transform_op_tag.c
+++ b/tests/expectations/transform_op_tag.c
@@ -13,13 +13,21 @@ struct StylePoint_f32 {
   float y;
 };
 
-enum StyleFoo_i32_Tag {
+enum StyleFoo_i32_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Foo_i32,
   Bar_i32,
   Baz_i32,
   Bazz_i32,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleFoo_i32_Tag StyleFoo_i32_Tag;
+#else
 typedef uint8_t StyleFoo_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct StyleFoo_Body_i32 {
   StyleFoo_i32_Tag tag;
@@ -100,12 +108,20 @@ struct StyleBar_u32 {
   };
 };
 
-enum StyleBaz_Tag {
+enum StyleBaz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Baz1,
   Baz2,
   Baz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleBaz_Tag StyleBaz_Tag;
+#else
 typedef uint8_t StyleBaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 union StyleBaz {
   StyleBaz_Tag tag;
@@ -119,12 +135,20 @@ union StyleBaz {
   };
 };
 
-enum StyleTaz_Tag {
+enum StyleTaz_Tag
+#if __STDC_VERSION__ >= 202311L
+  : uint8_t
+#endif // __STDC_VERSION__ >= 202311L
+ {
   Taz1,
   Taz2,
   Taz3,
 };
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleTaz_Tag StyleTaz_Tag;
+#else
 typedef uint8_t StyleTaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 
 struct StyleTaz {
   StyleTaz_Tag tag;
diff --git a/tests/expectations/transform_op_tag.compat.c b/tests/expectations/transform_op_tag.compat.c
index 3e6c48d8c..45bbe06ab 100644
--- a/tests/expectations/transform_op_tag.compat.c
+++ b/tests/expectations/transform_op_tag.compat.c
@@ -14,9 +14,9 @@ struct StylePoint_f32 {
 };
 
 enum StyleFoo_i32_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Foo_i32,
   Bar_i32,
@@ -24,7 +24,11 @@ enum StyleFoo_i32_Tag
   Bazz_i32,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleFoo_i32_Tag StyleFoo_i32_Tag;
+#else
 typedef uint8_t StyleFoo_i32_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct StyleFoo_Body_i32 {
@@ -107,16 +111,20 @@ struct StyleBar_u32 {
 };
 
 enum StyleBaz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Baz1,
   Baz2,
   Baz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleBaz_Tag StyleBaz_Tag;
+#else
 typedef uint8_t StyleBaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 union StyleBaz {
@@ -132,16 +140,20 @@ union StyleBaz {
 };
 
 enum StyleTaz_Tag
-#ifdef __cplusplus
+#if defined(__cplusplus) || __STDC_VERSION__ >= 202311L
   : uint8_t
-#endif // __cplusplus
+#endif // defined(__cplusplus) || __STDC_VERSION__ >= 202311L
  {
   Taz1,
   Taz2,
   Taz3,
 };
 #ifndef __cplusplus
+#if __STDC_VERSION__ >= 202311L
+typedef enum StyleTaz_Tag StyleTaz_Tag;
+#else
 typedef uint8_t StyleTaz_Tag;
+#endif // __STDC_VERSION__ >= 202311L
 #endif // __cplusplus
 
 struct StyleTaz {