libstdc++: Add attributes to <system_error> and related
Add the const attribute to std::future_category() and std::iostream_category(), to match the existing attributes on std::generic_category() and std::system_category(). Also add [[nodiscard]] to those functions and to the comparison operators for std::error_code and std::error_condition, and to std::make_error_code and std::make_error_condition overloads. libstdc++-v3/ChangeLog: * include/bits/ios_base.h (io_category): Add const and nodiscard attributes. (make_error_code, make_error_condition): Add nodiscard. * include/std/future (future_category): Add const and nodiscard. (make_error_code, make_error_condition): Add nodiscard. * include/std/system_error (generic_category system_category): Add nodiscard. Replace _GLIBCXX_CONST with C++11 attribute. (error_code::value, error_code::category, error_code::operator bool) (error_condition::value, error_condition::category) (error_condition::operator bool, make_error_code) (make_error_condition, operator==, operator!=, operator<=>): Add nodiscard.
This commit is contained in:
Jonathan Wakely
parent
c9852156dd
commit
5f1ce85135
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@ -205,12 +205,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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template <> struct is_error_code_enum<io_errc> : public true_type { };
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const error_category& iostream_category() noexcept;
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[[__nodiscard__, __gnu__::__const__]]
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const error_category&
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iostream_category() noexcept;
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[[__nodiscard__]]
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inline error_code
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make_error_code(io_errc __e) noexcept
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{ return error_code(static_cast<int>(__e), iostream_category()); }
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[[__nodiscard__]]
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inline error_condition
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make_error_condition(io_errc __e) noexcept
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{ return error_condition(static_cast<int>(__e), iostream_category()); }
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@ -82,15 +82,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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struct is_error_code_enum<future_errc> : public true_type { };
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/// Points to a statically-allocated object derived from error_category.
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[[__nodiscard__, __gnu__::__const__]]
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const error_category&
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future_category() noexcept;
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/// Overload of make_error_code for `future_errc`.
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[[__nodiscard__]]
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inline error_code
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make_error_code(future_errc __errc) noexcept
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{ return error_code(static_cast<int>(__errc), future_category()); }
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/// Overload of make_error_condition for `future_errc`.
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[[__nodiscard__]]
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inline error_condition
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make_error_condition(future_errc __errc) noexcept
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{ return error_condition(static_cast<int>(__errc), future_category()); }
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@ -153,12 +153,14 @@ _GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2)
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equivalent(const error_code& __code, int __i) const noexcept;
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/// An error_category only compares equal to itself.
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[[__nodiscard__]]
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bool
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operator==(const error_category& __other) const noexcept
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{ return this == &__other; }
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/// Ordered comparison that defines a total order for error categories.
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#if __cpp_lib_three_way_comparison
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[[nodiscard]]
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strong_ordering
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operator<=>(const error_category& __rhs) const noexcept
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{ return std::compare_three_way()(this, &__rhs); }
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@ -176,10 +178,14 @@ _GLIBCXX_BEGIN_INLINE_ABI_NAMESPACE(_V2)
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// DR 890.
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/// Error category for `errno` error codes.
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_GLIBCXX_CONST const error_category& generic_category() noexcept;
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[[__nodiscard__, __gnu__::__const__]]
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const error_category&
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generic_category() noexcept;
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/// Error category for other error codes defined by the OS.
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_GLIBCXX_CONST const error_category& system_category() noexcept;
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[[__nodiscard__, __gnu__::__const__]]
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const error_category&
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system_category() noexcept;
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/// @}
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@ -241,10 +247,12 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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{ return *this = make_error_code(__e); }
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/// The error value.
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[[__nodiscard__]]
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int
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value() const noexcept { return _M_value; }
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/// The error category that this error belongs to.
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[[__nodiscard__]]
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const error_category&
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category() const noexcept { return *_M_cat; }
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@ -259,6 +267,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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{ return category().message(value()); }
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/// Test whether `value()` is non-zero.
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[[__nodiscard__]]
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explicit operator bool() const noexcept
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{ return _M_value != 0; }
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@ -278,6 +287,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @relates error_code
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* @since C++11
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*/
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[[__nodiscard__]]
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inline error_code
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make_error_code(errc __e) noexcept
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{ return error_code(static_cast<int>(__e), generic_category()); }
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@ -291,6 +301,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @since C++11
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*/
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#if __cpp_lib_three_way_comparison
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[[nodiscard]]
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inline strong_ordering
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operator<=>(const error_code& __lhs, const error_code& __rhs) noexcept
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{
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@ -371,10 +382,12 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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// C++11 19.5.3.4 observers
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/// The error value.
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[[__nodiscard__]]
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int
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value() const noexcept { return _M_value; }
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/// The error category that this error belongs to.
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[[__nodiscard__]]
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const error_category&
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category() const noexcept { return *_M_cat; }
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@ -385,6 +398,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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{ return category().message(value()); }
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/// Test whether `value()` is non-zero.
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[[__nodiscard__]]
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explicit operator bool() const noexcept
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{ return _M_value != 0; }
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@ -404,6 +418,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @relates error_condition
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* @since C++11
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*/
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[[__nodiscard__]]
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inline error_condition
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make_error_condition(errc __e) noexcept
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{ return error_condition(static_cast<int>(__e), generic_category()); }
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@ -417,6 +432,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @relates error_condition
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* @since C++11
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*/
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[[__nodiscard__]]
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inline bool
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operator==(const error_code& __lhs, const error_code& __rhs) noexcept
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{
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@ -432,6 +448,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @relates error_condition
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* @since C++11
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*/
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[[__nodiscard__]]
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inline bool
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operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
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{
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@ -446,6 +463,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @relates error_condition
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* @since C++11
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*/
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[[__nodiscard__]]
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inline bool
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operator==(const error_condition& __lhs,
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const error_condition& __rhs) noexcept
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@ -463,6 +481,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
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* @since C++11
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*/
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#if __cpp_lib_three_way_comparison
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[[nodiscard]]
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inline strong_ordering
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operator<=>(const error_condition& __lhs,
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const error_condition& __rhs) noexcept
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