Rollup merge of #93269 - jacobbramley:dev/pauth-option-1, r=petrochenkov

Use error-on-mismatch policy for PAuth module flags.

This agrees with Clang, and avoids an error when using LTO with mixed
C/Rust. LLVM considers different behaviour flags to be a mismatch,
even when the flag value itself is the same.

This also makes the flag setting explicit for all uses of
LLVMRustAddModuleFlag.

----

I believe that this fixes #92885, but have only reproduced it locally on Linux hosts so cannot confirm that it fixes the issue as reported.

I have not included a test for this because it is covered by an existing test (`src/test/run-make-fulldeps/cross-lang-lto-clang`). It is not without its problems, though:
* The test requires Clang and `--run-clang-based-tests-with=...` to run, and this is not the case on the CI.
   * Any test I add would have a similar requirement.
* With this patch applied, the test gets further, but it still fails (for other reasons). I don't think that affects #92885.

1 files changed, 6 insertions, 3 deletions

diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index c21e4acbefe..dcd6327c92f 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -722,9 +722,12 @@ extern "C" bool LLVMRustIsRustLLVM() {
 #endif
 }
 
-extern "C" void LLVMRustAddModuleFlag(LLVMModuleRef M, const char *Name,
-                                      uint32_t Value) {
-  unwrap(M)->addModuleFlag(Module::Warning, Name, Value);
+extern "C" void LLVMRustAddModuleFlag(
+    LLVMModuleRef M,
+    Module::ModFlagBehavior MergeBehavior,
+    const char *Name,
+    uint32_t Value) {
+  unwrap(M)->addModuleFlag(MergeBehavior, Name, Value);
 }
 
 extern "C" LLVMValueRef LLVMRustMetadataAsValue(LLVMContextRef C, LLVMMetadataRef MD) {