https://gcc.gnu.org/g:f8c32184b85ce71c154fa96cd5ca700aab902656
commit r16-6547-gf8c32184b85ce71c154fa96cd5ca700aab902656 Author: Jakub Jelinek <[email protected]> Date: Wed Jan 7 15:00:50 2026 +0100 libstdc++: Use gnu_inline attribute on constexpr exception methods [PR123183] As mentioned in https://gcc.gnu.org/pipermail/gcc-patches/2026-January/704712.html in the gnu::constexpr_only thread, gnu::gnu_inline attribute actually seems to work for most of what we need for C++26 constexpr exceptions (i.e. when we want out of line bodies for C++ < 26 and need to use constexpr for C++26, yet don't want for reasons mentioned in those two PRs the bodies of those constexpr methods to be emitted inline). Unfortunately clang++ doesn't handle it 100% properly and requires the redundant inline keyword to make it work (even when the methods are constexpr and thus implicilty inline), g++ doesn't require that, so the patch adds also the redundant inline keywords and not just the [[__gnu__::__gnu_inline__]] attribute. This way if something wants to inline those functions it can, but if their address is taken, we just rely on libstdc++.{so,a} to provide those (which it does as before because those TUs are compiled with older -std= modes). The earlier r16-6477-gd5743234731 commit made sure gnu::gnu_inline constexpr virtual methods can be key methods, so vtables and rtti can be emitted only in the TU defining non-gnu_inline versions of those. 2026-01-07 Jakub Jelinek <[email protected]> PR libstdc++/123183 PR libstdc++/123326 * libsupc++/exception (std::bad_exception::~bad_exception(), std::bad_exception::what()): Add inline keyword and [[__gnu__::__gnu_inline__]] attribute to the C++26 constexpr exceptions definitions. * libsupc++/exception.h (std::exception::~exception(), std::exception::what()): Likewise. * libsupc++/exception_ptr.h (std::exception_ptr::exception_ptr(void*)): Likewise. * libsupc++/nested_exception.h (std::nested_exception::~nested_exception()): Likewise. * libsupc++/typeinfo (std::bad_cast::~bad_cast(), std::bad_cast::what(), std::bad_typeid::~bad_typeid(), std::bad_typeid::what()): Likewise. * include/bits/new_except.h (std::bad_alloc::~bad_alloc(), std::bad_alloc::what(), std::bad_array_new_length::~bad_array_new_length(), std::bad_array_new_length::what()): Likewise. * include/bits/stdexcept_except.h (std::logic_error::logic_error(const string&), std::logic_error::logic_error(const char*), std::logic_error::~logic_error(), std::logic_error::what(), std::domain_error::domain_error(const string&), std::domain_error::domain_error(const char*), std::invalid_argument::invalid_argument(const string&), std::invalid_argument::invalid_argument(const char*), std::length_error::length_error(const string&), std::length_error::length_error(const char*), std::out_of_range::out_of_range(const string&), std::out_of_range::out_of_range(const char*), std::runtime_error::runtime_error(const string&), std::runtime_error::runtime_error(const char*), std::runtime_error::~runtime_error(), std::runtime_error::what(), std::overflow_error::overflow_error(const string&), std::overflow_error::overflow_error(const char*), std::overflow_error::~overflow_error(), std::underflow_error::underflow_error(const string&), std::underflow_error::underflow_error(const char*), std::underflow_error::~underflow_error()): Likewise. (std::domain_error::~domain_error(), std::invalid_argument::~invalid_argument(), std::length_error::~length_error(), std::out_of_range::~out_of_range()): Likewise. Also change _GLIBCXX_NOTHROW to noexcept on those definitions. Diff: --- libstdc++-v3/include/bits/new_except.h | 12 ++-- libstdc++-v3/include/bits/stdexcept_except.h | 88 ++++++++++++++++++++-------- libstdc++-v3/libsupc++/exception | 7 ++- libstdc++-v3/libsupc++/exception.h | 6 +- libstdc++-v3/libsupc++/exception_ptr.h | 3 +- libstdc++-v3/libsupc++/nested_exception.h | 3 +- libstdc++-v3/libsupc++/typeinfo | 12 ++-- 7 files changed, 91 insertions(+), 40 deletions(-) diff --git a/libstdc++-v3/include/bits/new_except.h b/libstdc++-v3/include/bits/new_except.h index 18a2d1f82fed..e4f21fdd11e9 100644 --- a/libstdc++-v3/include/bits/new_except.h +++ b/libstdc++-v3/include/bits/new_except.h @@ -62,9 +62,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION #endif #if __cplusplus >= 202400L - constexpr virtual ~bad_alloc() noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~bad_alloc() noexcept {} - constexpr virtual const char* what() const noexcept + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const noexcept { return "std::bad_alloc"; } @@ -85,9 +87,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _GLIBCXX26_CONSTEXPR bad_array_new_length() throw() { } #if __cplusplus >= 202400L - constexpr virtual ~bad_array_new_length() noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~bad_array_new_length() noexcept {} - constexpr virtual const char* what() const noexcept + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const noexcept { return "std::bad_array_new_length"; } diff --git a/libstdc++-v3/include/bits/stdexcept_except.h b/libstdc++-v3/include/bits/stdexcept_except.h index a784d40fdf2c..6a43991c2240 100644 --- a/libstdc++-v3/include/bits/stdexcept_except.h +++ b/libstdc++-v3/include/bits/stdexcept_except.h @@ -258,11 +258,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit + [[__gnu__::__gnu_inline__]] + constexpr inline explicit logic_error(const string& __arg) _GLIBCXX_TXN_SAFE : _M_msg(__arg) {} - constexpr explicit + [[__gnu__::__gnu_inline__]] + constexpr inline explicit logic_error(const char* __arg) _GLIBCXX_TXN_SAFE : _M_msg(__arg) {} @@ -271,9 +273,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION constexpr logic_error(const logic_error&) noexcept = default; constexpr logic_error& operator=(const logic_error&) noexcept = default; - constexpr virtual ~logic_error() _GLIBCXX_TXN_SAFE_DYN noexcept { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~logic_error() _GLIBCXX_TXN_SAFE_DYN noexcept { } - constexpr virtual const char* + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const _GLIBCXX_TXN_SAFE_DYN noexcept { return _M_msg.c_str(); @@ -319,15 +323,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit domain_error(const string& __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit domain_error(const string& __arg) + _GLIBCXX_TXN_SAFE : logic_error(__arg) { } - constexpr explicit domain_error(const char* __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit domain_error(const char* __arg) _GLIBCXX_TXN_SAFE : logic_error(__arg) { } constexpr domain_error(const domain_error&) = default; constexpr domain_error& operator=(const domain_error&) = default; constexpr domain_error(domain_error&&) = default; constexpr domain_error& operator=(domain_error&&) = default; - constexpr virtual ~domain_error() _GLIBCXX_NOTHROW { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~domain_error() noexcept { } #else explicit domain_error(const string& __arg) _GLIBCXX_TXN_SAFE; #if __cplusplus >= 201103L @@ -346,15 +354,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit invalid_argument(const string& __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit invalid_argument(const string& __arg) + _GLIBCXX_TXN_SAFE : logic_error(__arg) { } - constexpr explicit invalid_argument(const char* __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit invalid_argument(const char* __arg) + _GLIBCXX_TXN_SAFE : logic_error(__arg) { } constexpr invalid_argument(const invalid_argument&) = default; constexpr invalid_argument& operator=(const invalid_argument&) = default; constexpr invalid_argument(invalid_argument&&) = default; constexpr invalid_argument& operator=(invalid_argument&&) = default; - constexpr virtual ~invalid_argument() _GLIBCXX_NOTHROW { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~invalid_argument() noexcept { } #else explicit invalid_argument(const string& __arg) _GLIBCXX_TXN_SAFE; #if __cplusplus >= 201103L @@ -374,15 +387,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit length_error(const string& __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit length_error(const string& __arg) + _GLIBCXX_TXN_SAFE : logic_error(__arg) { } - constexpr explicit length_error(const char* __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit length_error(const char* __arg) _GLIBCXX_TXN_SAFE : logic_error(__arg) { } constexpr length_error(const length_error&) = default; constexpr length_error& operator=(const length_error&) = default; constexpr length_error(length_error&&) = default; constexpr length_error& operator=(length_error&&) = default; - constexpr virtual ~length_error() _GLIBCXX_NOTHROW { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~length_error() noexcept { } #else explicit length_error(const string& __arg) _GLIBCXX_TXN_SAFE; #if __cplusplus >= 201103L @@ -402,15 +419,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit out_of_range(const string& __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit out_of_range(const string& __arg) + _GLIBCXX_TXN_SAFE : logic_error(__arg) { } - constexpr explicit out_of_range(const char* __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit out_of_range(const char* __arg) _GLIBCXX_TXN_SAFE : logic_error(__arg) { } constexpr out_of_range(const out_of_range&) = default; constexpr out_of_range& operator=(const out_of_range&) = default; constexpr out_of_range(out_of_range&&) = default; constexpr out_of_range& operator=(out_of_range&&) = default; - constexpr virtual ~out_of_range() _GLIBCXX_NOTHROW { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~out_of_range() noexcept { } #else explicit out_of_range(const string& __arg) _GLIBCXX_TXN_SAFE; #if __cplusplus >= 201103L @@ -435,11 +456,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit + [[__gnu__::__gnu_inline__]] + constexpr inline explicit runtime_error(const string& __arg) _GLIBCXX_TXN_SAFE : _M_msg(__arg) {} - constexpr explicit + [[__gnu__::__gnu_inline__]] + constexpr inline explicit runtime_error(const char* __arg) _GLIBCXX_TXN_SAFE : _M_msg(__arg) {} @@ -448,9 +471,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION constexpr runtime_error(const runtime_error&) noexcept = default; runtime_error& operator=(const runtime_error&) noexcept = default; - constexpr virtual ~runtime_error() _GLIBCXX_TXN_SAFE_DYN noexcept { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~runtime_error() _GLIBCXX_TXN_SAFE_DYN noexcept + {} - constexpr virtual const char* + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const _GLIBCXX_TXN_SAFE_DYN noexcept { return _M_msg.c_str(); @@ -495,15 +521,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit overflow_error(const string& __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit overflow_error(const string& __arg) + _GLIBCXX_TXN_SAFE : runtime_error(__arg) { } - constexpr explicit overflow_error(const char* __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit overflow_error(const char* __arg) + _GLIBCXX_TXN_SAFE : runtime_error(__arg) { } constexpr overflow_error(const overflow_error&) = default; constexpr overflow_error& operator=(const overflow_error&) = default; constexpr overflow_error(overflow_error&&) = default; constexpr overflow_error& operator=(overflow_error&&) = default; - constexpr virtual ~overflow_error() noexcept { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~overflow_error() noexcept { } #else explicit overflow_error(const string& __arg) _GLIBCXX_TXN_SAFE; #if __cplusplus >= 201103L @@ -522,15 +553,20 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { public: #if __cpp_lib_constexpr_exceptions >= 202502L - constexpr explicit underflow_error(const string& __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit underflow_error(const string& __arg) + _GLIBCXX_TXN_SAFE : runtime_error(__arg) { } - constexpr explicit underflow_error(const char* __arg) _GLIBCXX_TXN_SAFE + [[__gnu__::__gnu_inline__]] + constexpr inline explicit underflow_error(const char* __arg) + _GLIBCXX_TXN_SAFE : runtime_error(__arg) { } constexpr underflow_error(const underflow_error&) = default; constexpr underflow_error& operator=(const underflow_error&) = default; constexpr underflow_error(underflow_error&&) = default; constexpr underflow_error& operator=(underflow_error&&) = default; - constexpr virtual ~underflow_error() noexcept { } + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~underflow_error() noexcept { } #else explicit underflow_error(const string& __arg) _GLIBCXX_TXN_SAFE; #if __cplusplus >= 201103L diff --git a/libstdc++-v3/libsupc++/exception b/libstdc++-v3/libsupc++/exception index 5b402a3209cf..0ae01be25dd5 100644 --- a/libstdc++-v3/libsupc++/exception +++ b/libstdc++-v3/libsupc++/exception @@ -61,9 +61,12 @@ namespace std _GLIBCXX_VISIBILITY(default) _GLIBCXX26_CONSTEXPR bad_exception() _GLIBCXX_USE_NOEXCEPT { } #if __cplusplus >= 202400L - constexpr virtual ~bad_exception() _GLIBCXX_TXN_SAFE_DYN noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~bad_exception() _GLIBCXX_TXN_SAFE_DYN noexcept {} - constexpr virtual const char* what() const _GLIBCXX_TXN_SAFE_DYN noexcept + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const _GLIBCXX_TXN_SAFE_DYN + noexcept { return "std::bad_exception"; } diff --git a/libstdc++-v3/libsupc++/exception.h b/libstdc++-v3/libsupc++/exception.h index 30928eef7e8f..09a76ed62d8e 100644 --- a/libstdc++-v3/libsupc++/exception.h +++ b/libstdc++-v3/libsupc++/exception.h @@ -63,7 +63,8 @@ namespace std _GLIBCXX_VISIBILITY(default) public: _GLIBCXX26_CONSTEXPR exception() _GLIBCXX_NOTHROW { } #if __cplusplus >= 202400L - constexpr virtual ~exception() _GLIBCXX_TXN_SAFE_DYN noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~exception() _GLIBCXX_TXN_SAFE_DYN noexcept {} #else virtual ~exception() _GLIBCXX_TXN_SAFE_DYN _GLIBCXX_NOTHROW; #endif @@ -77,7 +78,8 @@ namespace std _GLIBCXX_VISIBILITY(default) /** Returns a C-style character string describing the general cause * of the current error. */ #if __cplusplus >= 202400L - constexpr virtual const char* + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const _GLIBCXX_TXN_SAFE_DYN noexcept { return "std::exception"; } #else virtual const char* diff --git a/libstdc++-v3/libsupc++/exception_ptr.h b/libstdc++-v3/libsupc++/exception_ptr.h index d31475a9eb62..b7a2304e121c 100644 --- a/libstdc++-v3/libsupc++/exception_ptr.h +++ b/libstdc++-v3/libsupc++/exception_ptr.h @@ -107,7 +107,8 @@ namespace std _GLIBCXX_VISIBILITY(default) void* _M_exception_object; #if __cplusplus >= 202400L - constexpr explicit exception_ptr(void* __e) noexcept + [[__gnu__::__gnu_inline__]] + constexpr inline explicit exception_ptr(void* __e) noexcept : _M_exception_object(__e) { if (_M_exception_object) diff --git a/libstdc++-v3/libsupc++/nested_exception.h b/libstdc++-v3/libsupc++/nested_exception.h index f4915e0fff3f..132f51dde60a 100644 --- a/libstdc++-v3/libsupc++/nested_exception.h +++ b/libstdc++-v3/libsupc++/nested_exception.h @@ -72,7 +72,8 @@ namespace std _GLIBCXX_VISIBILITY(default) nested_exception& operator=(const nested_exception&) noexcept = default; #if __cplusplus >= 202400L - constexpr virtual ~nested_exception() noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~nested_exception() noexcept {} #else virtual ~nested_exception() noexcept; #endif diff --git a/libstdc++-v3/libsupc++/typeinfo b/libstdc++-v3/libsupc++/typeinfo index 11de3ca4fa68..57f5f2d4c1df 100644 --- a/libstdc++-v3/libsupc++/typeinfo +++ b/libstdc++-v3/libsupc++/typeinfo @@ -227,9 +227,11 @@ namespace std _GLIBCXX26_CONSTEXPR bad_cast() _GLIBCXX_USE_NOEXCEPT { } #if __cplusplus >= 202400L - constexpr virtual ~bad_cast() noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~bad_cast() noexcept {} - constexpr virtual const char* what() const noexcept + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const noexcept { return "std::bad_cast"; } @@ -253,9 +255,11 @@ namespace std _GLIBCXX26_CONSTEXPR bad_typeid () _GLIBCXX_USE_NOEXCEPT { } #if __cplusplus >= 202400L - constexpr virtual ~bad_typeid() noexcept {} + [[__gnu__::__gnu_inline__]] + constexpr inline virtual ~bad_typeid() noexcept {} - constexpr virtual const char* what() const noexcept + [[__gnu__::__gnu_inline__]] + constexpr inline virtual const char* what() const noexcept { return "std::bad_typeid"; }
