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| author | Jonathan Wakely <jwakely@redhat.com> | 2022-04-01 12:25:02 +0100 |
|---|---|---|
| committer | Jonathan Wakely <jwakely@redhat.com> | 2022-04-01 13:17:18 +0100 |
| commit | babaabbcc8346758be0051b32272da18d54f5eea (patch) | |
| tree | 1a63a98ad862f3fa05fd8e12882a37795f4db7ce /libstdc++-v3/include/std/version | |
| parent | 944da70a5d1cdc5bd4327b2d32420f57b6883985 (diff) | |
| download | gcc-babaabbcc8346758be0051b32272da18d54f5eea.zip gcc-babaabbcc8346758be0051b32272da18d54f5eea.tar.gz gcc-babaabbcc8346758be0051b32272da18d54f5eea.tar.bz2 | |
libstdc++: Implement std::unreachable() for C++23 (P0627R6)
This defines std::unreachable as an assertion for debug mode, a trap
when _GLIBCXX_ASSERTIONS is defined, and __builtin_unreachable()
otherwise.
The reason for only using __builtin_trap() in the second case is to
avoid the overhead of setting up a call to __glibcxx_assert_fail that
should never happen.
UBsan can detect if __builtin_unreachable() is executed, so if a feature
test macro for that sanitizer is added, we could change just use
__builtin_unreachable() when the sanitizer is enabled.
While thinking about what the debug assertion failure should print, I
noticed that the __glibcxx_assert_fail function doesn't check for null
pointers. This adds a check so we don't try to print them if null.
libstdc++-v3/ChangeLog:
* include/std/utility (unreachable): Define for C++23.
* include/std/version (__cpp_lib_unreachable): Define.
* src/c++11/debug.cc (__glibcxx_assert_fail): Check for valid
arguments. Handle only the function being given.
* testsuite/20_util/unreachable/1.cc: New test.
* testsuite/20_util/unreachable/version.cc: New test.
Diffstat (limited to 'libstdc++-v3/include/std/version')
| -rw-r--r-- | libstdc++-v3/include/std/version | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version index 44b8a9f..51f2110 100644 --- a/libstdc++-v3/include/std/version +++ b/libstdc++-v3/include/std/version @@ -326,6 +326,7 @@ # define __cpp_lib_string_resize_and_overwrite 202110L #endif #define __cpp_lib_to_underlying 202102L +#define __cpp_lib_unreachable 202202L #endif #endif // C++2b #endif // C++20 |