rust-lang · JonathanBrouwer · Jan 19, 2026 · May 29, 2026 · May 29, 2026 · May 31, 2026
diff --git a/Cargo.lock b/Cargo.lock
@@ -6213,9 +6213,9 @@ dependencies = [
 
 [[package]]
 name = "wasi-preview1-component-adapter-provider"
-version = "44.0.2"
+version = "46.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2211ca2d69a88055eefb06bad741dde3180c9d4020f7e42fea72caba83f9c10c"
+checksum = "1b6c48003fe59c201c97a7786ff55feabe6b6f83b598aa9ff5bcc4f94d940bf3"
 
 [[package]]
 name = "wasip2"
@@ -6282,9 +6282,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-component-ld"
-version = "0.5.25"
+version = "0.5.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ee72c06c556db23aca2d29e1e183d96efdffa7110b24915629a5091de600a894"
+checksum = "51a12709376d4ce64f472699500db3b0e5902cc2bef16fb6ca3098bfdac032fa"
 dependencies = [
  "anyhow",
  "clap",
@@ -6293,12 +6293,12 @@ dependencies = [
  "libc",
  "tempfile",
  "wasi-preview1-component-adapter-provider",
- "wasmparser 0.252.0",
+ "wasmparser 0.253.0",
  "wat",
  "windows-sys 0.61.2",
  "winsplit",
- "wit-component 0.252.0",
- "wit-parser 0.252.0",
+ "wit-component 0.253.0",
+ "wit-parser 0.253.0",
 ]
 
 [[package]]
@@ -6330,12 +6330,12 @@ dependencies = [
 
 [[package]]
 name = "wasm-encoder"
-version = "0.252.0"
+version = "0.253.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8185ae345fa5687c054626ff9a50e7089797a343d9904d1dc9820eb4c4d3196f"
+checksum = "59972d6cd272259de647b7c1f1912e45e289c75ffd4be04e10695507cd7e1b59"
 dependencies = [
  "leb128fmt",
- "wasmparser 0.252.0",
+ "wasmparser 0.253.0",
 ]
 
 [[package]]
@@ -6352,14 +6352,14 @@ dependencies = [
 
 [[package]]
 name = "wasm-metadata"
-version = "0.252.0"
+version = "0.253.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b7e08e02a3cd55bf778009d4cd6faae50da011f293644daf78a531a32d6d142"
+checksum = "b3f45816ef616806f48498bcd831377de578c4fa51db0c83ab8ceb78cc13523b"
 dependencies = [
  "anyhow",
  "indexmap",
- "wasm-encoder 0.252.0",
- "wasmparser 0.252.0",
+ "wasm-encoder 0.253.0",
+ "wasmparser 0.253.0",
 ]
 
 [[package]]
@@ -6396,9 +6396,9 @@ dependencies = [
 
 [[package]]
 name = "wasmparser"
-version = "0.252.0"
+version = "0.253.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d3eb099dcadcde5be9eef55e3a337128efd4e44b4c93122487e4d2e4e1c6627c"
+checksum = "19db11f87d2486580e1e8b6f494c54df7e0566b87d0b599db843c24019667339"
 dependencies = [
  "bitflags",
  "hashbrown 0.17.0",
@@ -6409,22 +6409,22 @@ dependencies = [
 
 [[package]]
 name = "wast"
-version = "252.0.0"
+version = "253.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "942a3449d6a593fccc111a6241c8df52bda168af30e40bf9580d4394d7374c65"
+checksum = "d3264542f8965c5d84fb1085d924bfba9a6314bb228eff13a2de14d7627664d0"
 dependencies = [
  "bumpalo",
  "leb128fmt",
  "memchr",
  "unicode-width 0.2.2",
- "wasm-encoder 0.252.0",
+ "wasm-encoder 0.253.0",
 ]
 
 [[package]]
 name = "wat"
-version = "1.252.0"
+version = "1.253.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c72a4ba7088f7bac94cf516e49882bdf97068904a563768cf249efc839ec42cb"
+checksum = "4bfc5ce906144200c972ec617470aa35bd847472e170b26dde3e80541c674055"
 dependencies = [
  "wast",
 ]
@@ -6872,9 +6872,9 @@ dependencies = [
 
 [[package]]
 name = "wit-component"
-version = "0.252.0"
+version = "0.253.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "76db0662b590f45d33d0e363fa13539a5a1eecd35d5a12fe208c335461c1053d"
+checksum = "dbbd2500ac3488489ee8c6e59b79d7e47e6da5bfb019efd35d5dca57b78af624"
 dependencies = [
  "anyhow",
  "bitflags",
@@ -6883,10 +6883,10 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
- "wasm-encoder 0.252.0",
- "wasm-metadata 0.252.0",
- "wasmparser 0.252.0",
- "wit-parser 0.252.0",
+ "wasm-encoder 0.253.0",
+ "wasm-metadata 0.253.0",
+ "wasmparser 0.253.0",
+ "wit-parser 0.253.0",
 ]
 
 [[package]]
@@ -6909,9 +6909,9 @@ dependencies = [
 
 [[package]]
 name = "wit-parser"
-version = "0.252.0"
+version = "0.253.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4266bea110371c620ccf3201c5023676046bc4556e5c7cfb5d500bda5ebc162d"
+checksum = "4d997b8e5920fcbeec742b58e583325d6419a6aca617ae8075c406a61c65ba8a"
 dependencies = [
  "anyhow",
  "hashbrown 0.17.0",
@@ -6923,7 +6923,7 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "unicode-ident",
- "wasmparser 0.252.0",
+ "wasmparser 0.253.0",
 ]
 
 [[package]]

diff --git a/RELEASES.md b/RELEASES.md
@@ -1,3 +1,93 @@
+Version 1.97.0 (2026-07-09)
+==========================
+
+<a id="1.97.0-Language"></a>
+
+Language
+--------
+- [Consider `Result<T, Uninhabited>` and `ControlFlow<Uninhabited, T>` to be equivalent to `T` for must use lint](https://github.com/rust-lang/rust/pull/148214)
+- [Add allow-by-default `dead_code_pub_in_binary` lint for unused pub items in binary crates](https://github.com/rust-lang/rust/pull/149509)
+- [Stabilize the `div32`, `lam-bh`, `lamcas`, `ld-seq-sa` and `scq` target features](https://github.com/rust-lang/rust/pull/154510)
+- [Stabilize `cfg(target_has_atomic_primitive_alignment)`](https://github.com/rust-lang/rust/pull/155006)
+- [Allow trailing `self` in imports in more cases](https://github.com/rust-lang/rust/pull/155137)
+
+
+<a id="1.97.0-Platform-Support"></a>
+
+Platform Support
+----------------
+- [nvptx64-nvidia-cuda: drop support for old architectures and old ISAs](https://github.com/rust-lang/rust/pull/152443)
+
+
+Refer to Rust's [platform support page][platform-support-doc]
+for more information on Rust's tiered platform support.
+
+[platform-support-doc]: https://doc.rust-lang.org/rustc/platform-support.html
+
+
+<a id="1.97.0-Stabilized-APIs"></a>
+
+Stabilized APIs
+---------------
+
+- [`Default for RepeatN`](https://doc.rust-lang.org/stable/std/iter/struct.RepeatN.html#impl-Default-for-RepeatN%3CA%3E)
+- [`Copy for ffi::FromBytesUntilNulError`](https://doc.rust-lang.org/stable/std/ffi/struct.FromBytesUntilNulError.html#impl-Copy-for-FromBytesUntilNulError)
+- [`Send for std::fs::File` on UEFI](https://github.com/rust-lang/rust/pull/154003)
+- [`<{integer}>::isolate_highest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.isolate_highest_one)
+- [`<{integer}>::isolate_lowest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.isolate_lowest_one)
+- [`<{integer}>::highest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.highest_one)
+- [`<{integer}>::lowest_one`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.lowest_one)
+- [`<{integer}>::bit_width`](https://doc.rust-lang.org/stable/std/primitive.u32.html#method.bit_width)
+- [`NonZero<{integer}>::isolate_highest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.isolate_highest_one)
+- [`NonZero<{integer}>::isolate_lowest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.isolate_lowest_one)
+- [`NonZero<{integer}>::highest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.highest_one)
+- [`NonZero<{integer}>::lowest_one`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.lowest_one)
+- [`NonZero<{integer}>::bit_width`](https://doc.rust-lang.org/stable/std/num/struct.NonZero.html#method.bit_width)
+
+
+These previously stable APIs are now stable in const contexts:
+
+- [`char::is_control`](https://doc.rust-lang.org/stable/std/primitive.char.html#method.is_control)
+
+
+<a id="1.97.0-Cargo"></a>
+
+Cargo
+-----
+- [Stabilize `build.warnings` config.](https://github.com/rust-lang/cargo/pull/16796) This controls how lint warnings from local packages are treated. Useful for enforcing a warning-free build in CI, replacing `-Dwarnings`. [docs](https://doc.rust-lang.org/nightly/cargo/reference/config.html#buildwarnings)
+- [Stabilize `resolver.lockfile-path` config.](https://github.com/rust-lang/cargo/pull/16694) This allows specifying the path to the lockfile to use when resolving dependencies. Useful when working with read-only source directories. [docs](https://doc.rust-lang.org/nightly/cargo/reference/config.html#resolverlockfile-path)
+- [cargo-clean: Error when `--target-dir` doesn't look like a Cargo target directory.](https://github.com/rust-lang/cargo/pull/16712) This prevents accidental deletion of non-target directories.
+- [Add `-m` shorthand for `--manifest-path`](https://github.com/rust-lang/cargo/pull/16858)
+- [Remove `curl` dependency from `crates-io` crate](https://github.com/rust-lang/cargo/pull/16936)
+
+<a id="1.97.0-Rustdoc"></a>
+
+Rustdoc
+-----
+- [Stabilize `--emit` flag](https://github.com/rust-lang/rust/pull/146220)
+- [Stabilize `--remap-path-prefix`](https://github.com/rust-lang/rust/pull/155307)
+
+
+<a id="1.97.0-Compatibility-Notes"></a>
+
+Compatibility Notes
+-------------------
+- [Emit a future-compatibility warning when relying on `f32: From<{float}>` to constrain `{float}`](https://github.com/rust-lang/rust/pull/139087)
+- [Rust will use the v0 symbol mangling scheme by default.](https://github.com/rust-lang/rust/pull/151994) This may cause some tools (such as debuggers or profilers, especially with old versions) to fail to demangle symbols emitted by Rust. It may also cause the formatting of text in backtraces to change.
+- [Prevent deref coercions in `pin!`, in order to prevent unsoundness.](https://github.com/rust-lang/rust/pull/153457) The most likely case where this might impact users is: writing `pin!(x)` where `x` has type `&mut T` will now always correctly produce a value of type `Pin<&mut &mut T>`, instead of sometimes allowing a coercion that produces a value of type `Pin<&mut T>`. This coercion was previously incorrectly allowed since Rust 1.88.0.
+- [Deprecate `std::char` constants and functions](https://github.com/rust-lang/rust/pull/153873)
+- [Warn on linker output by default](https://github.com/rust-lang/rust/pull/153968)
+- [Remove hidden `f64` methods which have been deprecated since 1.0](https://github.com/rust-lang/rust/pull/153975)
+- [report the `varargs_without_pattern` lint in deps](https://github.com/rust-lang/rust/pull/154599)
+- [Forbid passing generic arguments to module path segments even if the module reexports a generic enum variant](https://github.com/rust-lang/rust/pull/154971)
+- [Error on invalid macho `link_section` specifier](https://github.com/rust-lang/rust/pull/155065)
+- The encoding of certain `enum`s [have changed](https://github.com/rust-lang/rust/pull/155473).  This is not a breaking change, as it only applies to `enum`s without layout guarantees, but is noted here as we've seen people impacted from having made assumptions about the layout algorithm.
+- [Error on `#[export_name = "..."]` where the name is empty](https://github.com/rust-lang/rust/pull/155515)
+- [Syntactically reject tuple index shorthands in struct patterns](https://github.com/rust-lang/rust/pull/155698)
+- [validate `#[link_name = "..."]` & `#[link(name = "...")]` parameters](https://github.com/rust-lang/rust/pull/155817)
+- On Windows, after calling `shutdown` on a socket to shut down the write side, attempting to write to the socket will now produce a `BrokenPipe` error rather than `Other`. [Map `WSAESHUTDOWN` to `io::ErrorKind::BrokenPipe`](https://github.com/rust-lang/rust/pull/156063)
+
+
 Version 1.96.1 (2026-06-30)
 ===========================
 

diff --git a/bootstrap.example.toml b/bootstrap.example.toml
@@ -973,6 +973,24 @@
 #dist.vendor = if "is a tarball source" || "is a git repository" { true } else { false }
 
 
+# =============================================================================
+# Profile-guided optimization options
+#
+# Configure the PGO profile to be used for compilation, or a path where the
+# profile will be written by an instrumented binary, for individual components
+# =============================================================================
+
+# Use the following profile to PGO optimize the Rust compiler.
+#pgo.rustc.use = "/tmp/profiles/foo.profraw"
+# Instrument the Rust compiler, so that when executed, it will gather profiles
+# to this path.
+#pgo.rustc.generate = "/tmp/profiles/foo.profraw"
+# Use the following profile to PGO optimize LLVM.
+#pgo.llvm.use = "/tmp/profiles/foo.profraw"
+# Instrument LLVM, so that when executed, it will gather profiles
+# Note: for LLVM specifically, this should be a directory, not a file path.
+#pgo.llvm.generate = "/tmp/profiles"
+
 # =============================================================================
 # Options for specific targets
 #

diff --git a/compiler/rustc_abi/src/callconv.rs b/compiler/rustc_abi/src/callconv.rs
@@ -89,7 +89,7 @@ impl<'a, Ty> TyAndLayout<'a, Ty> {
                 unreachable!("`homogeneous_aggregate` should not be called for scalable vectors")
             }
 
-            BackendRepr::ScalarPair(..) | BackendRepr::Memory { sized: true } => {
+            BackendRepr::ScalarPair { .. } | BackendRepr::Memory { sized: true } => {
                 // Helper for computing `homogeneous_aggregate`, allowing a custom
                 // starting offset (used below for handling variants).
                 let from_fields_at =

diff --git a/compiler/rustc_abi/src/layout.rs b/compiler/rustc_abi/src/layout.rs
@@ -476,7 +476,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             Err(AbiMismatch) | Ok(None) => BackendRepr::Memory { sized: true },
             Ok(Some((repr, _))) => match repr {
                 // Mismatched alignment (e.g. union is #[repr(packed)]): disable opt
-                BackendRepr::Scalar(_) | BackendRepr::ScalarPair(_, _)
+                BackendRepr::Scalar(_) | BackendRepr::ScalarPair { .. }
                     if repr.scalar_platform_align(dl).unwrap() != align =>
                 {
                     BackendRepr::Memory { sized: true }
@@ -489,7 +489,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                 }
                 // the alignment tests passed and we can use this
                 BackendRepr::Scalar(..)
-                | BackendRepr::ScalarPair(..)
+                | BackendRepr::ScalarPair { .. }
                 | BackendRepr::SimdVector { .. }
                 | BackendRepr::SimdScalableVector { .. }
                 | BackendRepr::Memory { .. } => repr,
@@ -558,7 +558,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             };
             match &mut st.backend_repr {
                 BackendRepr::Scalar(scalar) => hide_niches(scalar),
-                BackendRepr::ScalarPair(a, b) => {
+                BackendRepr::ScalarPair { a, b, b_offset: _ } => {
                     hide_niches(a);
                     hide_niches(b);
                 }
@@ -701,13 +701,21 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                     // When the total alignment and size match, we can use the
                     // same ABI as the scalar variant with the reserved niche.
                     BackendRepr::Scalar(_) => BackendRepr::Scalar(niche_scalar),
-                    BackendRepr::ScalarPair(first, second) => {
+                    BackendRepr::ScalarPair { a: first, b: second, b_offset } => {
                         // Only the niche is guaranteed to be initialised,
                         // so use union layouts for the other primitive.
                         if niche_offset == Size::ZERO {
-                            BackendRepr::ScalarPair(niche_scalar, second.to_union())
+                            BackendRepr::ScalarPair {
+                                a: niche_scalar,
+                                b: second.to_union(),
+                                b_offset,
+                            }
                         } else {
-                            BackendRepr::ScalarPair(first.to_union(), niche_scalar)
+                            BackendRepr::ScalarPair {
+                                a: first.to_union(),
+                                b: niche_scalar,
+                                b_offset,
+                            }
                         }
                     }
                     _ => BackendRepr::Memory { sized: true },
@@ -1037,7 +1045,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         // If we pick a "clever" (by-value) ABI, we might have to adjust the ABI of the
         // variants to ensure they are consistent. This is because a downcast is
         // semantically a NOP, and thus should not affect layout.
-        if matches!(abi, BackendRepr::Scalar(..) | BackendRepr::ScalarPair(..)) {
+        if matches!(abi, BackendRepr::Scalar(..) | BackendRepr::ScalarPair { .. }) {
             for variant in &mut layout_variants {
                 // We only do this for variants with fields; the others are not accessed anyway.
                 // Also do not overwrite any already existing "clever" ABIs.
@@ -1354,7 +1362,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                             }
                             // But scalar pairs are Rust-specific and get
                             // treated as aggregates by C ABIs anyway.
-                            BackendRepr::ScalarPair(..) => {
+                            BackendRepr::ScalarPair { .. } => {
                                 abi = field.backend_repr;
                             }
                             _ => {}

diff --git a/compiler/rustc_abi/src/layout/simple.rs b/compiler/rustc_abi/src/layout/simple.rs
@@ -110,7 +110,7 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
                 offsets: [Size::ZERO, b_offset].into(),
                 in_memory_order: [FieldIdx::new(0), FieldIdx::new(1)].into(),
             },
-            backend_repr: BackendRepr::ScalarPair(a, b),
+            backend_repr: BackendRepr::ScalarPair { a, b, b_offset },
             largest_niche,
             uninhabited: false,
             align: AbiAlign::new(align),