Revert "Silence -Wunused-parameter warnings in Unwind-wasm.c"

[sbc100]

Reverts #125412

See the discussion in #125412 for why this is necessary. The summary is that:

• Eliding arguments is the C23 extension, but libunwind builds its C files with -std=c99, so this change broke the build.
• -Wno-unused-parameter is part of the build for libunwind, so the codebase does allow them.

[llvmbot]

@llvm/pr-subscribers-libunwind

Author: Sam Clegg (sbc100)

Changes

Reverts llvm/llvm-project#125412

See the discussion in #125412 for why this is necessary. The summary is that:

• Eliding arguments is the C23 extension
• -Wno-unused-parameter is part of the build for libunwind, so the codebase does allow them.

---

Full diff: https://github.com/llvm/llvm-project/pull/175776.diff

1 Files Affected:

• (modified) libunwind/src/Unwind-wasm.c (+4-2)

diff --git a/libunwind/src/Unwind-wasm.c b/libunwind/src/Unwind-wasm.c
index b0d6cd2d00fc5..2f4498c3f3989 100644
--- a/libunwind/src/Unwind-wasm.c
+++ b/libunwind/src/Unwind-wasm.c
@@ -102,7 +102,8 @@ _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIP(struct _Unwind_Context *context) {
 }
 
 /// Not used in Wasm.
-_LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *, uintptr_t) {}
+_LIBUNWIND_EXPORT void _Unwind_SetIP(struct _Unwind_Context *context,
+                                     uintptr_t value) {}
 
 /// Called by personality handler to get LSDA for current frame.
 _LIBUNWIND_EXPORT uintptr_t
@@ -114,7 +115,8 @@ _Unwind_GetLanguageSpecificData(struct _Unwind_Context *context) {
 }
 
 /// Not used in Wasm.
-_LIBUNWIND_EXPORT uintptr_t _Unwind_GetRegionStart(struct _Unwind_Context *) {
+_LIBUNWIND_EXPORT uintptr_t
+_Unwind_GetRegionStart(struct _Unwind_Context *context) {
   return 0;
 }
 

[MaskRay]

Looks good, if idionne is happy.

Eliding arguments is the C23 extension, but libunwind builds its C files with -std=c99, so this change broke the build.

Does it break the build with very new clang? If yes, please include the information.

While I've read comments on #125412, it isn't clear to me why the change, merged on on Feb 17, 2025, was noticed only recently.

[sbc100]

Looks good, if idionne is happy.

Eliding arguments is the C23 extension, but libunwind builds its C files with -std=c99, so this change broke the build.

Does it break the build with very new clang? If yes, please include the information.

While I've read comments on #125412, it isn't clear to me why the change, merged on on Feb 17, 2025, was noticed only recently.

Because in emscripten (which is one of the primary consumers of the WebAssembly build of libunwind) only updates these libraries (libunwind/libcxx/etc) ever major release, and we noticed when trying to update to LLVM 21 in emscripten-core/emscripten#26036.

As far as I know there is no CI action that build these libraries for WebAssembly.