Fix typeinfo for undefined sanitizer

[MBkkt]

This happened to me when I compiled my code on x86_64 linux (ubuntu 24.04) with clang-18 and everything except clang, compiler_rt, glibc built from source (llvm 19, llvm source) in debug (-O1)

I found this solution and luckily it works!
emscripten-core/emscripten#13367 emscripten-core/emscripten#13330

I saw that issue is abandoned, so I decided to try to push it in upstream

[github-actions]

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[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Valery Mironov (MBkkt)

Changes

This happened to me when I compiled my code on x86_64 linux (ubuntu 24.04) with clang-18 and everything except glibc built from source (llvm 19, llvm source)

I found this solution and luckily it works!
emscripten-core/emscripten#13367 emscripten-core/emscripten#13330

I saw that issue is abandoned, so I decided to try to push it in upstream

---

Full diff: https://github.com/llvm/llvm-project/pull/121228.diff

1 Files Affected:

• (modified) libcxx/include/typeinfo (+2-1)

diff --git a/libcxx/include/typeinfo b/libcxx/include/typeinfo
index 799c6ebd5ecbbf..a900ccaf7e24bb 100644
--- a/libcxx/include/typeinfo
+++ b/libcxx/include/typeinfo
@@ -315,7 +315,8 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __impl::__hash(__type_name); }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
+  // We need to inline this code because otherwise we will get a stack overflow with undefined sanitizer.
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
     // When evaluated in a constant expression, both type infos simply can't come
     // from different translation units, so it is sufficient to compare their addresses.
     if (__libcpp_is_constant_evaluated()) {

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 815343e7dd32cc4c5c903ac52daf87aaa4e4cd6e 3d8fb18949dba038667e6d8983948b85a73cefdb --extensions  -- libcxx/include/typeinfo

View the diff from clang-format here.

diff --git a/libcxx/include/typeinfo b/libcxx/include/typeinfo
index a900ccaf7e..6bca852e21 100644
--- a/libcxx/include/typeinfo
+++ b/libcxx/include/typeinfo
@@ -316,7 +316,8 @@ public:
   _LIBCPP_HIDE_FROM_ABI size_t hash_code() const _NOEXCEPT { return __impl::__hash(__type_name); }
 
   // We need to inline this code because otherwise we will get a stack overflow with undefined sanitizer.
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const type_info& __arg) const _NOEXCEPT {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_ALWAYS_INLINE _LIBCPP_CONSTEXPR_SINCE_CXX23 bool
+  operator==(const type_info& __arg) const _NOEXCEPT {
     // When evaluated in a constant expression, both type infos simply can't come
     // from different translation units, so it is sufficient to compare their addresses.
     if (__libcpp_is_constant_evaluated()) {