1From 56b669cd7adcc413bb1e64c3d2d7c347a82ae35a Mon Sep 17 00:00:00 2001
2From: Khem Raj <raj.khem@gmail.com>
3Date: Wed, 21 May 2025 18:47:09 -0700
4Subject: [PATCH] Disable libunwind cross-architecture unwinding
5
6Building with _LIBUNWIND_IS_NATIVE_ONLY disables code for cross-architecture unwinding
7it is disabled by default in LLVM [1], replicate the cmake behavior in bootstrap process
8
9It also enables some additional code that handles PAC-specific unwind info
10it helps compiling with the -mbranch-protection=pac or -mbranch-protection=standard flags
11
12This fixes build with clang/musl on aarch64
13
14[1] https://github.com/llvm/llvm-project/commit/85624c5de3e831ffa01fdc2d159e3d69c30de08d
15
16Upstream-Status: Submitted [https://github.com/rust-lang/rust/pull/141375]
17Signed-off-by: Khem Raj <raj.khem@gmail.com>
18---
19 src/bootstrap/src/core/build_steps/llvm.rs | 3 +--
20 1 file changed, 1 insertion(+), 2 deletions(-)
21
22diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
23index a3788197471..5e4a1c7d9f0 100644
24--- a/src/bootstrap/src/core/build_steps/llvm.rs
25+++ b/src/bootstrap/src/core/build_steps/llvm.rs
26@@ -1430,6 +1430,7 @@ fn run(self, builder: &Builder<'_>) -> Self::Output {
27             cfg.flag("-funwind-tables");
28             cfg.flag("-fvisibility=hidden");
29             cfg.define("_LIBUNWIND_DISABLE_VISIBILITY_ANNOTATIONS", None);
30+            cfg.define("_LIBUNWIND_IS_NATIVE_ONLY", "1");
31             cfg.include(root.join("include"));
32             cfg.cargo_metadata(false);
33             cfg.out_dir(&out_dir);
34@@ -1447,12 +1448,10 @@ fn run(self, builder: &Builder<'_>) -> Self::Output {
35                 cfg.define("__NO_STRING_INLINES", None);
36                 cfg.define("__NO_MATH_INLINES", None);
37                 cfg.define("_LIBUNWIND_IS_BAREMETAL", None);
38-                cfg.define("__LIBUNWIND_IS_NATIVE_ONLY", None);
39                 cfg.define("NDEBUG", None);
40             }
41             if self.target.is_windows() {
42                 cfg.define("_LIBUNWIND_HIDE_SYMBOLS", "1");
43-                cfg.define("_LIBUNWIND_IS_NATIVE_ONLY", "1");
44             }
45         }
46
47