When I added this explicit specialization in r14-1433-gf150a084e25eaa I used the wrong value for the number of mantissa digits (I used 112 instead of 113). Then when I refactored it in r14-1582-g6261d10521f9fd I used the value calculated from the incorrect value (35 instead of 36). libstdc++-v3/ChangeLog: PR libstdc++/121374 * include/std/limits (numeric_limits<__float128>::max_digits10): Fix value. * testsuite/18_support/numeric_limits/128bit.cc: Check value.
Since LWG 3828 (included in C++23) implementations are allowed to have extended integer types that are wider than intmax_t. This means we no longer have to make is_integral_v<__int128> false for strict -std=c++23 mode, removing the confusing inconsistency with -std=gnu++23 (where is_integral_v<__int128> is true). This change makes __int128 a true integral type for all modes, treating LWG 3828 as a DR for previous standards. Most of the change just involves removing special cases where we wanted to treat __int128 and unsigned __int128 as integral types even when is_integral_v was false. There are still some preprocessor conditionals needed, because on some targets the compiler defines the macro __GLIBCXX_TYPE_INT_N_0 as __int128 in non-strict modes. Because we define explicit specializations of templates such as is_integral for all the INT_N types, we already have a specialization of is_integral<__int128> in non-strict modes, and so to avoid a redefinition we only must only define is_integral<__int128> for strict modes. libstdc++-v3/ChangeLog: PR libstdc++/96710 * include/bits/cpp_type_traits.h (__is_integer): Define explicit specializations for __int128. (__memcpyable_integer): Remove explicit specializations for __int128. * include/bits/iterator_concepts.h (incrementable_traits): Likewise. (__is_signed_int128, __is_unsigned_int128, __is_int128): Remove. (__is_integer_like, __is_signed_integer_like): Remove check for __int128. * include/bits/max_size_type.h: Remove all uses of __is_int128 in constraints. * include/bits/ranges_base.h (__to_unsigned_like): Remove overloads for __int128. (ranges::ssize): Remove special case for __int128. * include/bits/stl_algobase.h (__size_to_integer): Define __int128 overloads for strict modes. * include/ext/numeric_traits.h (__is_integer_nonstrict): Remove explicit specializations for __int128. * include/std/charconv (to_chars): Define overloads for __int128. * include/std/format (__format::make_unsigned_t): Remove. (__format::to_chars): Remove. * include/std/limits (numeric_limits): Define explicit specializations for __int128. * include/std/type_traits (__is_integral_helper): Likewise. (__make_unsigned, __make_signed): Likewise. Reviewed-by: Patrick Palka <ppalka@redhat.com>
In r15-3714-gd3a7302ec5985a I added -Wsystem-headers to the libstdc++ build flags to help catch problems in the library. This patch takes a different approach, of disabling the #pragma system_header unless _GLIBCXX_SYSHDR is defined. As a result, the testsuites will treat them as non-system-headers to get better warning coverage during regression testing of both gcc and libstdc++, not just when building the library. My rationale for the #ifdef instead of just removing the #pragma is the three G++ tests that want to test libstdc++ system header behavior, so we need a way to select it. This doesn't affect installed libraries, as they get their system-header status from the lookup path. But testsuite_flags --build-includes gives -I directives rather than -isystem. This patch doesn't change the headers in config/ because I'm not compiling with most of them, so won't see any warnings that need fixing. Adjusting them could happen later, or we can not bother. libstdc++-v3/ChangeLog: * acinclude.m4 (WARN_FLAGS): Remove -Wsystem-headers. * configure: Regenerate. * include/bits/algorithmfwd.h: #ifdef out #pragma GCC system_header. * include/bits/atomic_base.h * include/bits/atomic_futex.h * include/bits/atomic_timed_wait.h * include/bits/atomic_wait.h * include/bits/basic_ios.h * include/bits/basic_string.h * include/bits/boost_concept_check.h * include/bits/char_traits.h * include/bits/charconv.h * include/bits/chrono.h * include/bits/chrono_io.h * include/bits/codecvt.h * include/bits/concept_check.h * include/bits/cpp_type_traits.h * include/bits/elements_of.h * include/bits/enable_special_members.h * include/bits/erase_if.h * include/bits/forward_list.h * include/bits/functional_hash.h * include/bits/gslice.h * include/bits/gslice_array.h * include/bits/hashtable.h * include/bits/indirect_array.h * include/bits/invoke.h * include/bits/ios_base.h * include/bits/iterator_concepts.h * include/bits/locale_classes.h * include/bits/locale_facets.h * include/bits/locale_facets_nonio.h * include/bits/localefwd.h * include/bits/mask_array.h * include/bits/max_size_type.h * include/bits/memory_resource.h * include/bits/memoryfwd.h * include/bits/move_only_function.h * include/bits/node_handle.h * include/bits/ostream_insert.h * include/bits/out_ptr.h * include/bits/parse_numbers.h * include/bits/postypes.h * include/bits/quoted_string.h * include/bits/range_access.h * include/bits/ranges_base.h * include/bits/refwrap.h * include/bits/sat_arith.h * include/bits/semaphore_base.h * include/bits/slice_array.h * include/bits/std_abs.h * include/bits/std_function.h * include/bits/std_mutex.h * include/bits/std_thread.h * include/bits/stl_iterator_base_funcs.h * include/bits/stl_iterator_base_types.h * include/bits/stl_tree.h * include/bits/stream_iterator.h * include/bits/streambuf_iterator.h * include/bits/stringfwd.h * include/bits/this_thread_sleep.h * include/bits/unique_lock.h * include/bits/uses_allocator_args.h * include/bits/utility.h * include/bits/valarray_after.h * include/bits/valarray_array.h * include/bits/valarray_before.h * include/bits/version.h * include/c_compatibility/fenv.h * include/c_compatibility/inttypes.h * include/c_compatibility/stdint.h * include/decimal/decimal.h * include/experimental/bits/net.h * include/experimental/bits/shared_ptr.h * include/ext/aligned_buffer.h * include/ext/alloc_traits.h * include/ext/atomicity.h * include/ext/concurrence.h * include/ext/numeric_traits.h * include/ext/pod_char_traits.h * include/ext/pointer.h * include/ext/stdio_filebuf.h * include/ext/stdio_sync_filebuf.h * include/ext/string_conversions.h * include/ext/type_traits.h * include/ext/vstring.h * include/ext/vstring_fwd.h * include/ext/vstring_util.h * include/parallel/algorithmfwd.h * include/parallel/numericfwd.h * include/tr1/functional_hash.h * include/tr1/hashtable.h * include/tr1/random.h * libsupc++/exception.h * libsupc++/hash_bytes.h * include/bits/basic_ios.tcc * include/bits/basic_string.tcc * include/bits/fstream.tcc * include/bits/istream.tcc * include/bits/locale_classes.tcc * include/bits/locale_facets.tcc * include/bits/locale_facets_nonio.tcc * include/bits/ostream.tcc * include/bits/sstream.tcc * include/bits/streambuf.tcc * include/bits/string_view.tcc * include/bits/version.tpl * include/experimental/bits/string_view.tcc * include/ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp * include/ext/random.tcc * include/ext/vstring.tcc * include/tr2/bool_set.tcc * include/tr2/dynamic_bitset.tcc * include/bits/c++config * include/c/cassert * include/c/cctype * include/c/cerrno * include/c/cfloat * include/c/ciso646 * include/c/climits * include/c/clocale * include/c/cmath * include/c/csetjmp * include/c/csignal * include/c/cstdarg * include/c/cstddef * include/c/cstdio * include/c/cstdlib * include/c/cstring * include/c/ctime * include/c/cuchar * include/c/cwchar * include/c/cwctype * include/c_global/cassert * include/c_global/ccomplex * include/c_global/cctype * include/c_global/cerrno * include/c_global/cfenv * include/c_global/cfloat * include/c_global/cinttypes * include/c_global/ciso646 * include/c_global/climits * include/c_global/clocale * include/c_global/cmath * include/c_global/csetjmp * include/c_global/csignal * include/c_global/cstdalign * include/c_global/cstdarg * include/c_global/cstdbool * include/c_global/cstddef * include/c_global/cstdint * include/c_global/cstdio * include/c_global/cstdlib * include/c_global/cstring * include/c_global/ctgmath * include/c_global/ctime * include/c_global/cuchar * include/c_global/cwchar * include/c_global/cwctype * include/c_std/cassert * include/c_std/cctype * include/c_std/cerrno * include/c_std/cfloat * include/c_std/ciso646 * include/c_std/climits * include/c_std/clocale * include/c_std/cmath * include/c_std/csetjmp * include/c_std/csignal * include/c_std/cstdarg * include/c_std/cstddef * include/c_std/cstdio * include/c_std/cstdlib * include/c_std/cstring * include/c_std/ctime * include/c_std/cuchar * include/c_std/cwchar * include/c_std/cwctype * include/debug/array * include/debug/bitset * include/debug/deque * include/debug/forward_list * include/debug/list * include/debug/map * include/debug/set * include/debug/string * include/debug/unordered_map * include/debug/unordered_set * include/debug/vector * include/decimal/decimal * include/experimental/algorithm * include/experimental/any * include/experimental/array * include/experimental/buffer * include/experimental/chrono * include/experimental/contract * include/experimental/deque * include/experimental/executor * include/experimental/filesystem * include/experimental/forward_list * include/experimental/functional * include/experimental/internet * include/experimental/io_context * include/experimental/iterator * include/experimental/list * include/experimental/map * include/experimental/memory * include/experimental/memory_resource * include/experimental/net * include/experimental/netfwd * include/experimental/numeric * include/experimental/propagate_const * include/experimental/ratio * include/experimental/regex * include/experimental/scope * include/experimental/set * include/experimental/socket * include/experimental/string * include/experimental/string_view * include/experimental/synchronized_value * include/experimental/system_error * include/experimental/timer * include/experimental/tuple * include/experimental/type_traits * include/experimental/unordered_map * include/experimental/unordered_set * include/experimental/vector * include/ext/algorithm * include/ext/cmath * include/ext/functional * include/ext/iterator * include/ext/memory * include/ext/numeric * include/ext/random * include/ext/rb_tree * include/ext/rope * include/parallel/algorithm * include/std/algorithm * include/std/any * include/std/array * include/std/atomic * include/std/barrier * include/std/bit * include/std/bitset * include/std/charconv * include/std/chrono * include/std/codecvt * include/std/complex * include/std/concepts * include/std/condition_variable * include/std/coroutine * include/std/deque * include/std/execution * include/std/expected * include/std/filesystem * include/std/format * include/std/forward_list * include/std/fstream * include/std/functional * include/std/future * include/std/generator * include/std/iomanip * include/std/ios * include/std/iosfwd * include/std/iostream * include/std/istream * include/std/iterator * include/std/latch * include/std/limits * include/std/list * include/std/locale * include/std/map * include/std/memory * include/std/memory_resource * include/std/mutex * include/std/numbers * include/std/numeric * include/std/optional * include/std/ostream * include/std/print * include/std/queue * include/std/random * include/std/ranges * include/std/ratio * include/std/regex * include/std/scoped_allocator * include/std/semaphore * include/std/set * include/std/shared_mutex * include/std/span * include/std/spanstream * include/std/sstream * include/std/stack * include/std/stacktrace * include/std/stdexcept * include/std/streambuf * include/std/string * include/std/string_view * include/std/syncstream * include/std/system_error * include/std/text_encoding * include/std/thread * include/std/tuple * include/std/type_traits * include/std/typeindex * include/std/unordered_map * include/std/unordered_set * include/std/utility * include/std/valarray * include/std/variant * include/std/vector * include/std/version * include/tr1/array * include/tr1/cfenv * include/tr1/cinttypes * include/tr1/cmath * include/tr1/complex * include/tr1/cstdbool * include/tr1/cstdint * include/tr1/cstdio * include/tr1/cstdlib * include/tr1/cwchar * include/tr1/cwctype * include/tr1/functional * include/tr1/memory * include/tr1/random * include/tr1/regex * include/tr1/tuple * include/tr1/type_traits * include/tr1/unordered_map * include/tr1/unordered_set * include/tr1/utility * include/tr2/bool_set * include/tr2/dynamic_bitset * include/tr2/type_traits * libsupc++/atomic_lockfree_defines.h * libsupc++/compare * libsupc++/cxxabi.h * libsupc++/cxxabi_forced.h * libsupc++/cxxabi_init_exception.h * libsupc++/exception * libsupc++/initializer_list * libsupc++/new * libsupc++/typeinfo: Likewise. * testsuite/20_util/ratio/operations/ops_overflow_neg.cc * testsuite/23_containers/array/tuple_interface/get_neg.cc * testsuite/23_containers/vector/cons/destructible_debug_neg.cc * testsuite/24_iterators/operations/prev_neg.cc * testsuite/ext/type_traits/add_unsigned_floating_neg.cc * testsuite/ext/type_traits/add_unsigned_integer_neg.cc * testsuite/ext/type_traits/remove_unsigned_floating_neg.cc * testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: Adjust line numbers. gcc/testsuite/ChangeLog * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C * g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C * g++.dg/diagnostic/disable.C: #define _GLIBCXX_SYSHDR.
The use of #pragma GCC system_header in libstdc++ has led to bugs going undetected for a while due to the silencing of compiler warnings that would have revealed them promptly, and also interferes with warnings about problematic template instantiations induced by user code. But removing it, or even compiling with -Wsystem-header, is also problematic due to warnings about deliberate uses of extensions. So this patch adds #pragma GCC diagnostic as needed to suppress these warnings. The change to acinclude.m4 changes -Wabi to warn only in comparison to ABI 19, to avoid lots of warnings that we now mangle concept requirements, which are in any case still experimental. I checked for any other changes against ABI v15, and found only the <format> lambda mangling, which we can ignore. This also enables -Wsystem-headers while building the library, so we see any warnings not silenced by these #pragmas. libstdc++-v3/ChangeLog: * include/bits/algorithmfwd.h: * include/bits/allocator.h: * include/bits/codecvt.h: * include/bits/concept_check.h: * include/bits/cpp_type_traits.h: * include/bits/hashtable.h: * include/bits/iterator_concepts.h: * include/bits/ostream_insert.h: * include/bits/ranges_base.h: * include/bits/regex_automaton.h: * include/bits/std_abs.h: * include/bits/stl_algo.h: * include/c_compatibility/fenv.h: * include/c_compatibility/inttypes.h: * include/c_compatibility/stdint.h: * include/ext/concurrence.h: * include/ext/type_traits.h: * testsuite/ext/type_traits/add_unsigned_floating_neg.cc: * testsuite/ext/type_traits/add_unsigned_integer_neg.cc: * testsuite/ext/type_traits/remove_unsigned_floating_neg.cc: * testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: * include/bits/basic_ios.tcc: * include/bits/basic_string.tcc: * include/bits/fstream.tcc: * include/bits/istream.tcc: * include/bits/locale_classes.tcc: * include/bits/locale_facets.tcc: * include/bits/ostream.tcc: * include/bits/regex_compiler.tcc: * include/bits/sstream.tcc: * include/bits/streambuf.tcc: * configure: Regenerate. * include/bits/c++config: * include/c/cassert: * include/c/cctype: * include/c/cerrno: * include/c/cfloat: * include/c/climits: * include/c/clocale: * include/c/cmath: * include/c/csetjmp: * include/c/csignal: * include/c/cstdarg: * include/c/cstddef: * include/c/cstdio: * include/c/cstdlib: * include/c/cstring: * include/c/ctime: * include/c/cwchar: * include/c/cwctype: * include/c_global/climits: * include/c_global/cmath: * include/c_global/cstddef: * include/c_global/cstdlib: * include/decimal/decimal: * include/ext/rope: * include/std/any: * include/std/charconv: * include/std/complex: * include/std/coroutine: * include/std/format: * include/std/iomanip: * include/std/limits: * include/std/numbers: * include/tr1/functional: * include/tr1/tuple: * include/tr1/type_traits: * libsupc++/compare: * libsupc++/new: Add #pragma GCC diagnostic to suppress undesired warnings. * acinclude.m4: Change -Wabi version from 2 to 19. gcc/ChangeLog: * ginclude/stdint-wrap.h: Add #pragma GCC diagnostic to suppress undesired warnings. * gsyslimits.h: Likewise.
In r14-3304-g1a566fddea212a and r14-3305-g6cf214b4fc97f5 I tried to enable std::format for 16-bit float types before C++23. This causes errors for targets where the types are defined but can't actually be used, e.g. i686 without sse2. Make the std::numeric_limits and std::formatter specializations for _Float16 and __bfloat16_t depend on the __STDCPP_FLOAT16_T__ and __STDCPP_BFLOAT16_T__ macros again, so they're only defined for C++23 when the type is fully supported. This is OK because the main point of my earlier commits was to add better support for _Float32 and _Float64. It seems fine for the new 16-bit types to only be supported for C++23, as they were never present before GCC 13 anyway. libstdc++-v3/ChangeLog: PR target/111060 * include/std/format (formatter): Only define specializations for 16-bit floating-point types for C++23. * include/std/limits (numeric_limits): Likewise.
The extended floating-point types such as _Float32 are supported by GCC prior to C++23, you just can't use the standard-conforming names from <stdfloat> to refer to them. This change defines the specializations of std::numeric_limits for those types for older dialects, not only for C++23. libstdc++-v3/ChangeLog: * include/bits/c++config (__gnu_cxx::__bfloat16_t): Define whenever __BFLT16_DIG__ is defined, not only for C++23. * include/std/limits (numeric_limits<bfloat16_t>): Likewise. (numeric_limits<_Float16>, numeric_limits<_Float32>) (numeric_limits<_Float64>): Likewise for other extended floating-point types.
This redefines std::numeric_limits<__float128> so that it works with non-GCC compilers. The previous definition didn't work with Clang, due to it not supporting __builtin_high_valq, __builtin_nanq, and __builtin_nansq. It also didn't work in strict modes, due to using Q literal suffixes. The new definition uses the Q suffixes when supported, or calculates the correct values using __float128 arithmetic from double values. Ideally the values would be defined as hexadecimal-floating-point-literals, but that won't work for C++14 and older. The only member that can't be defined this way is signaling_NaN() which still requires a built-in. If __builtin_nansq is not supported, try to use __builtin_nansf128 (with a possibly-redundant bit_cast) and if that isn't supported, return a quiet NaN and define has_signaling_NaN and is_iec754 to be false. libstdc++-v3/ChangeLog: PR libstdc++/104772 * include/std/limits: (numeric_limits<__float128>): Define for __STRICT_ANSI__ as well. * testsuite/18_support/numeric_limits/128bit.cc: Remove check for __STRICT_ANSI__. Co-authored-by: Jakub Jelinek <jakub@redhat.com>
As suggested by Jakub in the PR, this just hardcodes the constants with a Q suffix, since the properties of __float128 are not going to change. We can only define it for non-strict modes because the suffix gives an error otherwise, even in system headers: limits:2085: error: unable to find numeric literal operator 'operator""Q' libstdc++-v3/ChangeLog: PR libstdc++/104772 * include/std/limits (numeric_limits<__float128>): Define. * testsuite/18_support/numeric_limits/128bit.cc: New test.