[libcxx-commits] [libcxx] [libcxxabi] [libc++] Replace uses of _LIBCPP_WEAK with [[gnu::weak]] (PR #171798)
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Jan 9 03:15:48 PST 2026
https://github.com/philnik777 updated https://github.com/llvm/llvm-project/pull/171798
>From 3413c5f76fb060266a2cab587ede3fd41d2d0a1b Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Thu, 11 Dec 2025 11:48:53 +0100
Subject: [PATCH] [libc++] Replase uses of _LIBCPP_WEAK with [[gnu::weak]]
---
libcxx/.clang-format | 1 -
libcxx/include/__config | 4 ---
libcxx/src/experimental/tzdb.cpp | 2 +-
libcxx/src/include/overridable_function.h | 7 ++---
libcxx/src/new.cpp | 32 ++++++++++----------
libcxx/src/verbose_abort.cpp | 2 +-
libcxxabi/src/stdlib_new_delete.cpp | 36 ++++++++++-------------
7 files changed, 37 insertions(+), 47 deletions(-)
diff --git a/libcxx/.clang-format b/libcxx/.clang-format
index 9557b955cd72c..38f8fdb0703f6 100644
--- a/libcxx/.clang-format
+++ b/libcxx/.clang-format
@@ -53,7 +53,6 @@ AttributeMacros: [
'_LIBCPP_TRY_ACQUIRE_CAPABILITY',
'_LIBCPP_TRY_ACQUIRE_SHARED_CAPABILITY',
'_LIBCPP_USING_IF_EXISTS',
- '_LIBCPP_WEAK',
]
BinPackArguments: false
BinPackParameters: false
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 4b1763d69d9e9..b933f3f65a827 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -610,10 +610,6 @@ typedef __char32_t char32_t;
# define _LIBCPP_CONSTEXPR_SINCE_CXX26
# endif
-# ifndef _LIBCPP_WEAK
-# define _LIBCPP_WEAK __attribute__((__weak__))
-# endif
-
// Thread API
// clang-format off
# if _LIBCPP_HAS_THREADS && \
diff --git a/libcxx/src/experimental/tzdb.cpp b/libcxx/src/experimental/tzdb.cpp
index 3dc92fb7b7f2d..fd976ba4bd799 100644
--- a/libcxx/src/experimental/tzdb.cpp
+++ b/libcxx/src/experimental/tzdb.cpp
@@ -53,7 +53,7 @@ _LIBCPP_DIAGNOSTIC_PUSH
_LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wmissing-prototypes")
// This function is weak so it can be overriden in the tests. The
// declaration is in the test header test/support/test_tzdb.h
-_LIBCPP_WEAK string_view __libcpp_tzdb_directory() {
+[[gnu::weak]] string_view __libcpp_tzdb_directory() {
#if defined(__linux__)
return "/usr/share/zoneinfo/";
#else
diff --git a/libcxx/src/include/overridable_function.h b/libcxx/src/include/overridable_function.h
index 288f3efa9c979..c8d9f30c74c3e 100644
--- a/libcxx/src/include/overridable_function.h
+++ b/libcxx/src/include/overridable_function.h
@@ -66,8 +66,7 @@
#if defined(_LIBCPP_OBJECT_FORMAT_MACHO)
# define _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION 1
-# define OVERRIDABLE_FUNCTION \
- __attribute__((__section__("__TEXT,__lcxx_override,regular,pure_instructions"))) _LIBCPP_WEAK
+# define OVERRIDABLE_FUNCTION [[gnu::weak, gnu::section("__TEXT,__lcxx_override,regular,pure_instructions")]]
_LIBCPP_BEGIN_NAMESPACE_STD template <typename T, T* _Func>
_LIBCPP_HIDE_FROM_ABI inline bool __is_function_overridden() noexcept {
@@ -99,7 +98,7 @@ _LIBCPP_END_NAMESPACE_STD
#elif defined(_LIBCPP_OBJECT_FORMAT_ELF) && !defined(__NVPTX__)
# define _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION 1
-# define OVERRIDABLE_FUNCTION __attribute__((__section__("__lcxx_override"))) _LIBCPP_WEAK
+# define OVERRIDABLE_FUNCTION [[gnu::weak, gnu::section("__lcxx_override")]]
// This is very similar to what we do for Mach-O above. The ELF linker will implicitly define
// variables with those names corresponding to the start and the end of the section.
@@ -127,7 +126,7 @@ _LIBCPP_END_NAMESPACE_STD
#else
# define _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION 0
-# define OVERRIDABLE_FUNCTION _LIBCPP_WEAK
+# define OVERRIDABLE_FUNCTION [[gnu::weak]]
#endif
diff --git a/libcxx/src/new.cpp b/libcxx/src/new.cpp
index 505d239930d81..25bdaea32f57a 100644
--- a/libcxx/src/new.cpp
+++ b/libcxx/src/new.cpp
@@ -50,7 +50,7 @@ OVERRIDABLE_FUNCTION void* operator new(std::size_t size) _THROW_BAD_ALLOC {
return p;
}
-_LIBCPP_WEAK void* operator new(size_t size, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new(size_t size, const std::nothrow_t&) noexcept {
# if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -76,7 +76,7 @@ _LIBCPP_WEAK void* operator new(size_t size, const std::nothrow_t&) noexcept {
OVERRIDABLE_FUNCTION void* operator new[](size_t size) _THROW_BAD_ALLOC { return ::operator new(size); }
-_LIBCPP_WEAK void* operator new[](size_t size, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new[](size_t size, const std::nothrow_t&) noexcept {
# if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -100,17 +100,17 @@ _LIBCPP_WEAK void* operator new[](size_t size, const std::nothrow_t&) noexcept {
# endif
}
-_LIBCPP_WEAK void operator delete(void* ptr) noexcept { std::free(ptr); }
+[[gnu::weak]] void operator delete(void* ptr) noexcept { std::free(ptr); }
-_LIBCPP_WEAK void operator delete(void* ptr, const std::nothrow_t&) noexcept { ::operator delete(ptr); }
+[[gnu::weak]] void operator delete(void* ptr, const std::nothrow_t&) noexcept { ::operator delete(ptr); }
-_LIBCPP_WEAK void operator delete(void* ptr, size_t) noexcept { ::operator delete(ptr); }
+[[gnu::weak]] void operator delete(void* ptr, size_t) noexcept { ::operator delete(ptr); }
-_LIBCPP_WEAK void operator delete[](void* ptr) noexcept { ::operator delete(ptr); }
+[[gnu::weak]] void operator delete[](void* ptr) noexcept { ::operator delete(ptr); }
-_LIBCPP_WEAK void operator delete[](void* ptr, const std::nothrow_t&) noexcept { ::operator delete[](ptr); }
+[[gnu::weak]] void operator delete[](void* ptr, const std::nothrow_t&) noexcept { ::operator delete[](ptr); }
-_LIBCPP_WEAK void operator delete[](void* ptr, size_t) noexcept { ::operator delete[](ptr); }
+[[gnu::weak]] void operator delete[](void* ptr, size_t) noexcept { ::operator delete[](ptr); }
# if _LIBCPP_HAS_LIBRARY_ALIGNED_ALLOCATION
@@ -141,7 +141,7 @@ OVERRIDABLE_FUNCTION void* operator new(std::size_t size, std::align_val_t align
return p;
}
-_LIBCPP_WEAK void* operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
# if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -169,7 +169,7 @@ OVERRIDABLE_FUNCTION void* operator new[](size_t size, std::align_val_t alignmen
return ::operator new(size, alignment);
}
-_LIBCPP_WEAK void* operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
# if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -193,25 +193,25 @@ _LIBCPP_WEAK void* operator new[](size_t size, std::align_val_t alignment, const
# endif
}
-_LIBCPP_WEAK void operator delete(void* ptr, std::align_val_t) noexcept { std::__libcpp_aligned_free(ptr); }
+[[gnu::weak]] void operator delete(void* ptr, std::align_val_t) noexcept { std::__libcpp_aligned_free(ptr); }
-_LIBCPP_WEAK void operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
::operator delete(ptr, alignment);
}
-_LIBCPP_WEAK void operator delete(void* ptr, size_t, std::align_val_t alignment) noexcept {
+[[gnu::weak]] void operator delete(void* ptr, size_t, std::align_val_t alignment) noexcept {
::operator delete(ptr, alignment);
}
-_LIBCPP_WEAK void operator delete[](void* ptr, std::align_val_t alignment) noexcept {
+[[gnu::weak]] void operator delete[](void* ptr, std::align_val_t alignment) noexcept {
::operator delete(ptr, alignment);
}
-_LIBCPP_WEAK void operator delete[](void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void operator delete[](void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
::operator delete[](ptr, alignment);
}
-_LIBCPP_WEAK void operator delete[](void* ptr, size_t, std::align_val_t alignment) noexcept {
+[[gnu::weak]] void operator delete[](void* ptr, size_t, std::align_val_t alignment) noexcept {
::operator delete[](ptr, alignment);
}
diff --git a/libcxx/src/verbose_abort.cpp b/libcxx/src/verbose_abort.cpp
index 94bdb451dee7a..afe20c3cd0b16 100644
--- a/libcxx/src/verbose_abort.cpp
+++ b/libcxx/src/verbose_abort.cpp
@@ -23,7 +23,7 @@ extern "C" void android_set_abort_message(const char* msg);
_LIBCPP_BEGIN_NAMESPACE_STD
-_LIBCPP_WEAK void __libcpp_verbose_abort(char const* format, ...) noexcept {
+[[gnu::weak]] void __libcpp_verbose_abort(char const* format, ...) noexcept {
// Write message to stderr. We do this before formatting into a
// buffer so that we still get some information out if that fails.
{
diff --git a/libcxxabi/src/stdlib_new_delete.cpp b/libcxxabi/src/stdlib_new_delete.cpp
index 783357c4351be..164a26335eb38 100644
--- a/libcxxabi/src/stdlib_new_delete.cpp
+++ b/libcxxabi/src/stdlib_new_delete.cpp
@@ -20,10 +20,6 @@
# error The _THROW_BAD_ALLOC macro should be already defined by libc++
#endif
-#ifndef _LIBCPP_WEAK
-# error The _LIBCPP_WEAK macro should be already defined by libc++
-#endif
-
#if defined(_LIBCXXABI_NO_EXCEPTIONS) != !_LIBCPP_HAS_EXCEPTIONS
# error libc++ and libc++abi seem to disagree on whether exceptions are enabled
#endif
@@ -70,7 +66,7 @@ OVERRIDABLE_FUNCTION void* operator new(std::size_t size) _THROW_BAD_ALLOC {
return p;
}
-_LIBCPP_WEAK void* operator new(size_t size, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new(size_t size, const std::nothrow_t&) noexcept {
#if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -96,7 +92,7 @@ _LIBCPP_WEAK void* operator new(size_t size, const std::nothrow_t&) noexcept {
OVERRIDABLE_FUNCTION void* operator new[](size_t size) _THROW_BAD_ALLOC { return ::operator new(size); }
-_LIBCPP_WEAK void* operator new[](size_t size, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new[](size_t size, const std::nothrow_t&) noexcept {
#if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -120,17 +116,17 @@ _LIBCPP_WEAK void* operator new[](size_t size, const std::nothrow_t&) noexcept {
#endif
}
-_LIBCPP_WEAK void operator delete(void* ptr) noexcept { std::free(ptr); }
+[[gnu::weak]] void operator delete(void* ptr) noexcept { std::free(ptr); }
-_LIBCPP_WEAK void operator delete(void* ptr, const std::nothrow_t&) noexcept { ::operator delete(ptr); }
+[[gnu::weak]] void operator delete(void* ptr, const std::nothrow_t&) noexcept { ::operator delete(ptr); }
-_LIBCPP_WEAK void operator delete(void* ptr, size_t) noexcept { ::operator delete(ptr); }
+[[gnu::weak]] void operator delete(void* ptr, size_t) noexcept { ::operator delete(ptr); }
-_LIBCPP_WEAK void operator delete[](void* ptr) noexcept { ::operator delete(ptr); }
+[[gnu::weak]] void operator delete[](void* ptr) noexcept { ::operator delete(ptr); }
-_LIBCPP_WEAK void operator delete[](void* ptr, const std::nothrow_t&) noexcept { ::operator delete[](ptr); }
+[[gnu::weak]] void operator delete[](void* ptr, const std::nothrow_t&) noexcept { ::operator delete[](ptr); }
-_LIBCPP_WEAK void operator delete[](void* ptr, size_t) noexcept { ::operator delete[](ptr); }
+[[gnu::weak]] void operator delete[](void* ptr, size_t) noexcept { ::operator delete[](ptr); }
#if _LIBCPP_HAS_LIBRARY_ALIGNED_ALLOCATION
@@ -161,7 +157,7 @@ OVERRIDABLE_FUNCTION void* operator new(std::size_t size, std::align_val_t align
return p;
}
-_LIBCPP_WEAK void* operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new(size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
# if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -189,7 +185,7 @@ OVERRIDABLE_FUNCTION void* operator new[](size_t size, std::align_val_t alignmen
return ::operator new(size, alignment);
}
-_LIBCPP_WEAK void* operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void* operator new[](size_t size, std::align_val_t alignment, const std::nothrow_t&) noexcept {
# if !_LIBCPP_HAS_EXCEPTIONS
# if _LIBCPP_CAN_DETECT_OVERRIDDEN_FUNCTION
_LIBCPP_ASSERT_SHIM(
@@ -213,25 +209,25 @@ _LIBCPP_WEAK void* operator new[](size_t size, std::align_val_t alignment, const
# endif
}
-_LIBCPP_WEAK void operator delete(void* ptr, std::align_val_t) noexcept { std::__libcpp_aligned_free(ptr); }
+[[gnu::weak]] void operator delete(void* ptr, std::align_val_t) noexcept { std::__libcpp_aligned_free(ptr); }
-_LIBCPP_WEAK void operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void operator delete(void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
::operator delete(ptr, alignment);
}
-_LIBCPP_WEAK void operator delete(void* ptr, size_t, std::align_val_t alignment) noexcept {
+[[gnu::weak]] void operator delete(void* ptr, size_t, std::align_val_t alignment) noexcept {
::operator delete(ptr, alignment);
}
-_LIBCPP_WEAK void operator delete[](void* ptr, std::align_val_t alignment) noexcept {
+[[gnu::weak]] void operator delete[](void* ptr, std::align_val_t alignment) noexcept {
::operator delete(ptr, alignment);
}
-_LIBCPP_WEAK void operator delete[](void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
+[[gnu::weak]] void operator delete[](void* ptr, std::align_val_t alignment, const std::nothrow_t&) noexcept {
::operator delete[](ptr, alignment);
}
-_LIBCPP_WEAK void operator delete[](void* ptr, size_t, std::align_val_t alignment) noexcept {
+[[gnu::weak]] void operator delete[](void* ptr, size_t, std::align_val_t alignment) noexcept {
::operator delete[](ptr, alignment);
}
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