The bitwise operators for combining bitmask types such as std::launch
are not consistently annotated with noexcept, constexpr, and nodiscard.
This is the subject of LWG 3977, although the proposed resolution
doesn't work. We can make the changes in libstdc++ anyway though.
libstdc++-v3/ChangeLog:
* include/bits/atomic_base.h (operator|, operator&): Add
noexcept.
* include/bits/fs_fwd.h (operator&, operator|, operator^)
(operator~): Add nodiscard to overloads for copy_options, perms,
perm_options, and directory_options.
* include/bits/ios_base.h (operator&, operator|, operator^)
(operator~): Add nodiscard and noexcept to overloads for
_Ios_Fmtflags, _Ios_Openmode, and _Ios_Iostate.
(operator|=, operator&=, operator^=): Add constexpr for C++14.
* include/bits/regex_constants.h (operator&, operator|, operator^)
(operator~): Add nodiscard and noexcept to overloads for
syntax_option_type and match_flag_type.
(operator|=, operator&=, operator^=): Add noexcept.
* include/std/charconv (operator&, operator|, operator^)
(operator~): Add nodiscard to overloads for chars_format.
* include/std/future (operator&, operator|, operator^)
(operator~): Add nodiscard for overloads for launch.
(operator&=, operator|=, operator^=): Add constexpr for C++14.
* include/experimental/bits/fs_fwd.h (operator&, operator|)
(operator^, operator~): Add nodiscard to overloads for
copy_options, perms, and directory_options.
* testsuite/27_io/ios_base/types/fmtflags/bitmask_operators.cc:
Add dg-warning for nodiscard warnings.
* testsuite/27_io/ios_base/types/iostate/bitmask_operators.cc:
Likewise.
* testsuite/27_io/ios_base/types/openmode/bitmask_operators.cc:
Likewise.
* testsuite/27_io/filesystem/operations/bitmask_types.cc:
New test.
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