Hide ImageFormat From traits to avoid LLVM PC32 relocation limits

pixel_bridge/build_defs.bzl

@@ -0,0 +1,18 @@
+"""Build definitions for pixel bridge."""
+
+# Platforms where Rust decoding is unavailable.
+UNSUPPORTED_PLATFORMS_RUST = (
+    "//tools/cc_target_os:chromiumos",
+    "//tools/cc_target_os:darwin",
+    "//tools/cc_target_os:fuchsia",
+    "//tools/cc_target_os:android",
+    "//tools/cc_target_os:wasm",
+    "//tools/cc_target_os:hercules_embedded",
+    "//tools/cc_target_os:platform_ios",
+    "//tools/cc_target_os:platform_tvos",
+    "//tools/cc_target_os:platform_visionos",
+    "//tools/cc_target_os:platform_watchos",
+    "//tools/cc_target_os:mpu64",
+    "//tools/cc_target_os:nestcam_ambarella",
+    "//tools/cc_target_os:windows",
+)

pixel_bridge/rust/image.rs

@@ -286,17 +286,24 @@ impl Frames {
 }
 
 fn format_panic(err: Box<dyn std::any::Any + Send>) -> String {
-    let backtrace = std::backtrace::Backtrace::capture();
     let msg = if let Some(msg) = err.downcast_ref::<&str>() {
         *msg
     } else if let Some(msg) = err.downcast_ref::<String>() {
         msg.as_str()
     } else {
         "Unknown panic payload"
     };
+
+    // Capturing backtraces under TSAN can cause deadlocks.
+    let backtrace = if std::env::var("RUST_BACKTRACE").is_ok() {
+        format!("\nBacktrace:\n{}", std::backtrace::Backtrace::capture())
+    } else {
+        String::new()
+    };
+
     // This error message needs to start with "Rust panic caught", as
     // that is how we identify it on the C++ side.
-    format!("Rust panic caught: {}\nBacktrace:\n{}", msg, backtrace)
+    format!("Rust panic caught: {}{}", msg, backtrace)
 }
 
 fn run_catching_panics<F, T>(f: F) -> Result<T, String>