rust: Disable cross-unwinding support in llvm libunwind

This is default in LLVM but rust does not use cmake to build itself
so it needs to replicate the behavior

Fixes rust build with clang/musl for aarch64

Signed-off-by: Khem Raj <[email protected]>
Signed-off-by: Mathieu Dubois-Briand <[email protected]>
Signed-off-by: Richard Purdie <[email protected]>
(adapted from oe-core commit f05d42d11e56cbbda6034bd7f773dc690b68bdbd)
Signed-off-by: Scott Murray <[email protected]>

Author: kraj

recipes-devtools/rust/files/0001-Disable-libunwind-cross-architecture-unwinding.patch

@@ -0,0 +1,46 @@
+From 56b669cd7adcc413bb1e64c3d2d7c347a82ae35a Mon Sep 17 00:00:00 2001
+From: Khem Raj <[email protected]>
+Date: Wed, 21 May 2025 18:47:09 -0700
+Subject: [PATCH] Disable libunwind cross-architecture unwinding
+
+Building with _LIBUNWIND_IS_NATIVE_ONLY disables code for cross-architecture unwinding
+it is disabled by default in LLVM [1], replicate the cmake behavior in bootstrap process
+
+It also enables some additional code that handles PAC-specific unwind info
+it helps compiling with the -mbranch-protection=pac or -mbranch-protection=standard flags
+
+This fixes build with clang/musl on aarch64
+
+[1] https://github.com/llvm/llvm-project/commit/85624c5de3e831ffa01fdc2d159e3d69c30de08d
+
+Upstream-Status: Submitted [https://github.com/rust-lang/rust/pull/141375]
+Signed-off-by: Khem Raj <[email protected]>
+---
+ src/bootstrap/src/core/build_steps/llvm.rs | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
+index a3788197471..5e4a1c7d9f0 100644
+--- a/src/bootstrap/src/core/build_steps/llvm.rs
++++ b/src/bootstrap/src/core/build_steps/llvm.rs
+@@ -1430,6 +1430,7 @@ fn run(self, builder: &Builder<'_>) -> Self::Output {
+             cfg.flag("-funwind-tables");
+             cfg.flag("-fvisibility=hidden");
+             cfg.define("_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS", None);
++            cfg.define("_LIBUNWIND_IS_NATIVE_ONLY", "1");
+             cfg.include(root.join("include"));
+             cfg.cargo_metadata(false);
+             cfg.out_dir(&out_dir);
+@@ -1447,12 +1448,10 @@ fn run(self, builder: &Builder<'_>) -> Self::Output {
+                 cfg.define("__NO_STRING_INLINES", None);
+                 cfg.define("__NO_MATH_INLINES", None);
+                 cfg.define("_LIBUNWIND_IS_BAREMETAL", None);
+-                cfg.define("__LIBUNWIND_IS_NATIVE_ONLY", None);
+                 cfg.define("NDEBUG", None);
+             }
+             if self.target.is_windows() {
+                 cfg.define("_LIBUNWIND_HIDE_SYMBOLS", "1");
+-                cfg.define("_LIBUNWIND_IS_NATIVE_ONLY", "1");
+             }
+         }
+ 

recipes-devtools/rust/rust-source.inc

@@ -9,6 +9,7 @@ SRC_URI += "https://static.rust-lang.org/dist/rustc-${RUST_VERSION}-src.tar.xz;n
             file://revert-link-std-statically-in-rustc_driver-feature.patch;patchdir=${RUSTSRC} \
             file://Zdual-proc-macros-additional-check.patch;patchdir=${RUSTSRC} \
             file://0001-libunwind-Use-gcs-instead-of-gcs-target-attribute.patch;patchdir=${RUSTSRC} \
+            file://0001-Disable-libunwind-cross-architecture-unwinding.patch;patchdir=${RUSTSRC} \
 "
 SRC_URI[rust.sha256sum] = "b1fbf809efe9f036939401e142631c201a53bcf43ec1696bd9f5290ba236a266"