gcc/libstdc++-v3
Jonathan Wakely 74d14778e7 libstdc++: Define std::__is_constant_evaluated() for internal use
This adds std::__is_constant_evaluated() as a C++11 wrapper for
__builtin_is_constant_evaluated, but just returning false if the
built-in isn't supported by the compiler. This allows us to use it
throughout the library without checking __has_builtin every time.

Some uses in std::vector and std::string can only be constexpr when the
std::is_constant_evaluated() function actually works, so we might as
well guard them with a relevant macro and call that function directly,
rather than the built-in or std::__is_constant_evaluated().

The remaining checks of the __cpp_lib_is_constant_evaluated macro could
now be replaced by checking __cplusplus >= 202002 instead, but there's
no practical difference. We still need some kind of preprocessor check
there anyway.

libstdc++-v3/ChangeLog:

	* doc/doxygen/user.cfg.in (PREDEFINED): Change macro name.
	* include/bits/allocator.h (allocate, deallocate): Use
	std::__is_constant_evaluated() unconditionally, instead of
	checking whether std::is_constant_evaluated() (or the built-in)
	can be used.
	* include/bits/basic_string.h: Check new macro. call
	std::is_constant_evaluated() directly in C++20-only code that is
	guarded by a suitable macro.
	* include/bits/basic_string.tcc: Likewise.
	* include/bits/c++config (__is_constant_evaluated): Define.
	(_GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED): Replace with ...
	(_GLIBCXX_HAVE_IS_CONSTANT_EVALUATED): New macro.
	* include/bits/char_traits.h (char_traits): Replace conditional
	calls to std::is_constant_evaluated with unconditional calls to
	std::__is_constant_evaluated.
	* include/bits/cow_string.h: Use new macro.
	* include/bits/ranges_algobase.h (__copy_or_move): Replace
	conditional calls to std::is_constant_evaluated with unconditional
	calls to std::__is_constant_evaluated.
	(__copy_or_move_backward, __fill_n_fn): Likewise.
	* include/bits/ranges_cmp.h (ranges::less): Likewise.
	* include/bits/stl_algobase.h (lexicographical_compare_three_way):
	Likewise.
	* include/bits/stl_bvector.h: Call std::is_constant_evaluated
	directly in C++20-only code that is guarded by a suitable macro.
	* include/bits/stl_construct.h (_Construct, _Destroy, _Destroy_n):
	Replace is_constant_evaluated with __is_constant_evaluated.
	* include/bits/stl_function.h (greater, less, greater_equal)
	(less_equal): Replace __builtin_is_constant_evaluated and
	__builtin_constant_p with __is_constant_evaluated.
	* include/bits/stl_vector.h: Call std::is_constant_evaluated()
	in C++20-only code.
	* include/debug/helper_functions.h (__check_singular): Use
	__is_constant_evaluated instead of built-in, or remove check
	entirely.
	* include/std/array (operator<=>): Use __is_constant_evaluated
	unconditionally.
	* include/std/bit (__bit_ceil): Likewise.
	* include/std/type_traits (is_constant_evaluated): Define using
	'if consteval' if possible.
	* include/std/version: Use new macro.
	* libsupc++/compare: Use __is_constant_evaluated instead of
	__builtin_is_constant_evaluated.
	* testsuite/23_containers/array/tuple_interface/get_neg.cc:
	Adjust dg-error lines.
2021-12-01 15:00:33 +00:00
..
config libstdc++: Make Asan detection work for Clang [PR103453] 2021-11-30 20:10:19 +00:00
doc libstdc++: Define std::__is_constant_evaluated() for internal use 2021-12-01 15:00:33 +00:00
include libstdc++: Define std::__is_constant_evaluated() for internal use 2021-12-01 15:00:33 +00:00
libsupc++ libstdc++: Define std::__is_constant_evaluated() for internal use 2021-12-01 15:00:33 +00:00
po Update copyright years. 2021-01-04 10:26:59 +01:00
python libstdc++: Fix pretty printing of std::unique_ptr [PR103086] 2021-11-04 22:50:02 +00:00
scripts libstdc++: Improve generated man pages for libstdc++ 2021-10-21 22:24:57 +01:00
src libstdc++: Avoid unwanted allocations in filesystem::path 2021-12-01 15:00:32 +00:00
testsuite libstdc++: Define std::__is_constant_evaluated() for internal use 2021-12-01 15:00:33 +00:00
acinclude.m4 libstdc++: Replace AC_CACHE_VAL with AC_CACHE_CHECK 2021-11-18 13:56:33 +00:00
aclocal.m4
ChangeLog Daily bump. 2021-12-01 00:17:04 +00:00
ChangeLog-1998
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ChangeLog-2019
ChangeLog-2020 libstdc++: Fix typo in ChangeLog-2020 2021-01-13 11:02:13 +00:00
config.h.in libstdc++: Support getentropy and arc4random in std::random_device 2021-11-09 14:40:33 +00:00
configure libstdc++: Replace AC_CACHE_VAL with AC_CACHE_CHECK 2021-11-18 13:56:33 +00:00
configure.ac libstdc++: Support getentropy and arc4random in std::random_device 2021-11-09 14:40:33 +00:00
configure.host Scope libstdc++ configuration for vxworks to all versions 2020-10-22 16:40:57 +00:00
crossconfig.m4 libstdc++: Check for TLS support on mingw cross-compilers 2021-09-15 09:49:33 +01:00
fragment.am libstdc++: Add C++ runtime support for new 128-bit long double format 2020-12-16 23:25:01 +00:00
linkage.m4
Makefile.am Update copyright years. 2021-01-04 10:26:59 +01:00
Makefile.in libstdc++: Add C++ runtime support for new 128-bit long double format 2020-12-16 23:25:01 +00:00
README

file: libstdc++-v3/README

New users may wish to point their web browsers to the file
index.html in the 'doc/html' subdirectory.  It contains brief
building instructions and notes on how to configure the library in
interesting ways.