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| author | Jonathan Wakely <jwakely@redhat.com> | 2022-01-10 17:28:19 +0000 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2022-01-11 13:22:35 +0000 |
| commit | 5b417b35824fb5c15e3ee958cb86436b3409ebea (patch) | |
| tree | 200cfb1337a68b8be3cc6c976272aece4f0ec425 | |
| parent | 11d3e8f4364b05e2746689c6d0f573594f6ddb74 (diff) | |
| download | gcc-5b417b35824fb5c15e3ee958cb86436b3409ebea.zip gcc-5b417b35824fb5c15e3ee958cb86436b3409ebea.tar.gz gcc-5b417b35824fb5c15e3ee958cb86436b3409ebea.tar.bz2 | |
libstdc++: Make std::variant work with Clang in C++20 mode [PR103891]
Clang has some bugs with destructors that use constraints to be
conditionally trivial, so disable the P2231R1 constexpr changes to
std::variant unless the compiler is GCC 12 or later.
If/when P2493R0 gets accepted and implemented by G++ we can remove the
__GNUC__ check and use __cpp_concepts >= 202002 instead.
libstdc++-v3/ChangeLog:
PR libstdc++/103891
* include/bits/c++config (_GLIBCXX_HAVE_COND_TRIVIAL_SPECIAL_MEMBERS):
Define.
* include/std/variant (__cpp_lib_variant): Only define C++20
value when the compiler is known to support conditionally
trivial destructors.
* include/std/version (__cpp_lib_variant): Likewise.
| -rw-r--r-- | libstdc++-v3/include/bits/c++config | 5 | ||||
| -rw-r--r-- | libstdc++-v3/include/std/variant | 7 | ||||
| -rw-r--r-- | libstdc++-v3/include/std/version | 5 |
3 files changed, 12 insertions, 5 deletions
diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config index c64b61b..b197349 100644 --- a/libstdc++-v3/include/bits/c++config +++ b/libstdc++-v3/include/bits/c++config @@ -810,6 +810,11 @@ namespace std #undef _GLIBCXX_HAS_BUILTIN +#if __cplusplus >= 202002L && __cpp_concepts && __GNUC__ >= 12 +// XXX workaround for missing feature test macro for P0848R3 (see P2493R0). +# define _GLIBCXX_HAVE_COND_TRIVIAL_SPECIAL_MEMBERS 1 +#endif + // PSTL configuration #if __cplusplus >= 201703L diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant index d74939e..c41f9f2 100644 --- a/libstdc++-v3/include/std/variant +++ b/libstdc++-v3/include/std/variant @@ -44,9 +44,10 @@ #include <bits/stl_iterator_base_funcs.h> #include <bits/stl_construct.h> #include <bits/utility.h> // in_place_index_t -#if __cplusplus == 201703L +#ifndef _GLIBCXX_HAVE_COND_TRIVIAL_SPECIAL_MEMBERS # include <ext/aligned_buffer.h> -#else +#endif +#if __cplusplus >= 202002L # include <compare> #endif @@ -54,7 +55,7 @@ namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION -#if __cplusplus >= 202002L && __cpp_concepts +#ifdef _GLIBCXX_HAVE_COND_TRIVIAL_SPECIAL_MEMBERS // P2231R1 constexpr needs constexpr unions and constrained destructors. # define __cpp_lib_variant 202106L #else diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version index f421056..012d78e 100644 --- a/libstdc++-v3/include/std/version +++ b/libstdc++-v3/include/std/version @@ -173,7 +173,8 @@ # define __cpp_lib_to_chars 201611L #endif #define __cpp_lib_unordered_map_try_emplace 201411 -#if __cplusplus == 201703L || ! __cpp_concepts // N.B. updated value in C++20 +#ifndef _GLIBCXX_HAVE_COND_TRIVIAL_SPECIAL_MEMBERS +// N.B. updated value in C++20 # define __cpp_lib_variant 202102L #endif #endif @@ -286,7 +287,7 @@ # endif #define __cpp_lib_to_address 201711L #define __cpp_lib_to_array 201907L -#if __cpp_concepts +#ifdef _GLIBCXX_HAVE_COND_TRIVIAL_SPECIAL_MEMBERS # define __cpp_lib_variant 202106L #endif #endif |