From: Jonathan Wakely Date: Wed, 19 Jul 2023 17:18:46 +0000 (+0100) Subject: libstdc++: Check for std::ratio in arithmetic and comparisons [PR110593] X-Git-Tag: releases/gcc-12.4.0~328 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ae8302e18f15f0befb372762b20a3a790a19a925;p=thirdparty%2Fgcc.git libstdc++: Check for std::ratio in arithmetic and comparisons [PR110593] The standard says that it should be ill-formed to use std::ratio_equal etc. with types which are not specializations of std::ratio. This implements that requirement. We don't need to add assertions to every one of the class templates, because many of them are implemented in terms of other ones. For example, ratio_divide and ratio_subtract can rely on the assertions in ratio_multiply and ratio_add respectively. libstdc++-v3/ChangeLog: PR libstdc++/110593 * include/bits/chrono.h (duration): Improve static assert messages. (__is_ratio): Move to ... * include/std/ratio (__is_ratio): ... here. (__is_ratio_v): New variable template and partial specialization. (__are_both_ratios): New function template. (__ratio_multiply, ratio_equal, ratio_less, __ratio_add): Add static assertion. * testsuite/20_util/ratio/requirements/type_constraints.cc: New test. * testsuite/20_util/duration/requirements/typedefs_neg1.cc: Adjust expected error. * testsuite/20_util/duration/requirements/typedefs_neg2.cc: Likewise. (cherry picked from commit 2d614822e9ea2a3d8800045d66e3220743753d09) --- diff --git a/libstdc++-v3/include/bits/chrono.h b/libstdc++-v3/include/bits/chrono.h index c585cac3d8aa..d09f8563a599 100644 --- a/libstdc++-v3/include/bits/chrono.h +++ b/libstdc++-v3/include/bits/chrono.h @@ -483,26 +483,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { return numeric_limits<_Rep>::lowest(); } }; - /// @cond undocumented - - template - struct __is_ratio - : std::false_type - { }; - - template - struct __is_ratio> - : std::true_type - { }; - - /// @endcond - template class duration { - static_assert(!__is_duration<_Rep>::value, "rep cannot be a duration"); + static_assert(!__is_duration<_Rep>::value, + "rep cannot be a std::chrono::duration"); static_assert(__is_ratio<_Period>::value, - "period must be a specialization of ratio"); + "period must be a specialization of std::ratio"); static_assert(_Period::num > 0, "period must be positive"); template diff --git a/libstdc++-v3/include/std/ratio b/libstdc++-v3/include/std/ratio index 5a5643d2999b..32a4da25a937 100644 --- a/libstdc++-v3/include/std/ratio +++ b/libstdc++-v3/include/std/ratio @@ -289,9 +289,43 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION /// @cond undocumented + template + struct __is_ratio + : std::false_type + { }; + + template + struct __is_ratio> + : std::true_type + { }; + +#if __cpp_variable_templates + template + constexpr bool __is_ratio_v = false; + template + constexpr bool __is_ratio_v> = true; +#endif + + template + constexpr bool + __are_both_ratios() noexcept + { +#if __cpp_variable_templates && __cpp_if_constexpr + if constexpr (__is_ratio_v<_R1>) + if constexpr (__is_ratio_v<_R2>) + return true; + return false; +#else + return __and_<__is_ratio<_R1>, __is_ratio<_R2>>::value; +#endif + } + template struct __ratio_multiply { + static_assert(std::__are_both_ratios<_R1, _R2>(), + "both template arguments must be a std::ratio"); + private: static const intmax_t __gcd1 = __static_gcd<_R1::num, _R2::den>::value; @@ -356,7 +390,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template struct ratio_equal : integral_constant - { }; + { + static_assert(std::__are_both_ratios<_R1, _R2>(), + "both template arguments must be a std::ratio"); + }; /// ratio_not_equal template @@ -402,7 +439,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template struct ratio_less : __ratio_less_impl<_R1, _R2>::type - { }; + { + static_assert(std::__are_both_ratios<_R1, _R2>(), + "both template arguments must be a std::ratio"); + }; /// ratio_less_equal template @@ -430,13 +470,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template inline constexpr bool ratio_less_v = ratio_less<_R1, _R2>::value; template - inline constexpr bool ratio_less_equal_v = - ratio_less_equal<_R1, _R2>::value; + inline constexpr bool ratio_less_equal_v + = ratio_less_equal<_R1, _R2>::value; template inline constexpr bool ratio_greater_v = ratio_greater<_R1, _R2>::value; template inline constexpr bool ratio_greater_equal_v - = ratio_greater_equal<_R1, _R2>::value; + = ratio_greater_equal<_R1, _R2>::value; #endif // C++17 /// @cond undocumented @@ -513,6 +553,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template struct __ratio_add { + static_assert(std::__are_both_ratios<_R1, _R2>(), + "both template arguments must be a std::ratio"); + typedef typename __ratio_add_impl<_R1, _R2>::type type; static constexpr intmax_t num = type::num; static constexpr intmax_t den = type::den; diff --git a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc index 6e473acf19ca..d71e31f9b59c 100644 --- a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc +++ b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc @@ -29,4 +29,4 @@ void test01() test_type d; // { dg-error "required from here" } } -// { dg-error "rep cannot be a duration" "" { target *-*-* } 0 } +// { dg-error "rep cannot be a std::chrono::duration" "" { target *-*-* } 0 } diff --git a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc index 39409e21fcc2..0c0329b3fd1d 100644 --- a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc +++ b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc @@ -30,7 +30,7 @@ void test01() test_type d; // { dg-error "required from here" } } -// { dg-error "must be a specialization of ratio" "" { target *-*-* } 0 } +// { dg-error "must be a specialization of std::ratio" "" { target *-*-* } 0 } // { dg-prune-output "'num' is not a member of 'int'" } // { dg-prune-output "'den' is not a member of 'int'" } // { dg-prune-output "'int' is not a class, struct, or union type" } diff --git a/libstdc++-v3/testsuite/20_util/ratio/requirements/type_constraints.cc b/libstdc++-v3/testsuite/20_util/ratio/requirements/type_constraints.cc new file mode 100644 index 000000000000..ebf09bc8f077 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/ratio/requirements/type_constraints.cc @@ -0,0 +1,34 @@ +// { dg-do compile { target c++11 } } + +// C++11 20.10.1 [ratio.general] +// if the template argument types R1 and R2 are not specializations of the +// ratio template, the program is ill-formed. + +#include + +using namespace std; + +// A type that looks like std::ratio but isn't. +template struct Ratty { static constexpr int num = 1, den = 1; }; + +using T1 = ratio_add, Ratty<1>>::type; // { dg-error "here" } +using T2 = ratio_subtract, Ratty<3>>::type; // { dg-error "here" } +using T3 = ratio_multiply, Ratty<3>>::type; // { dg-error "here" } +using T4 = ratio_divide, Ratty<4>>::type; // { dg-error "here" } +using T5 = ratio_equal, Ratty<5>>::type; // { dg-error "here" } +using T6 = ratio_not_equal, Ratty<6>>::type; // { dg-error "here" } +using T7 = ratio_less, Ratty<7>>::type; // { dg-error "here" } +using T8 = ratio_less_equal, Ratty<8>>::type; // { dg-error "here" } +using T9 = ratio_greater, Ratty<9>>::type; // { dg-error "here" } +using T10 = ratio_greater_equal, Ratty<10>>::type; // { dg-error "here" } + +#if __cplusplus >= 201703L +bool B11 = ratio_equal_v, Ratty<11>>; // { dg-error "here" "" { target c++17 } } +bool B12 = ratio_not_equal_v, Ratty<12>>; // { dg-error "here" "" { target c++17 } } +bool B13 = ratio_less_v, Ratty<13>>; // { dg-error "here" "" { target c++17 } } +bool B14 = ratio_less_equal_v, Ratty<14>>; // { dg-error "here" "" { target c++17 } } +bool B15 = ratio_greater_v, Ratty<15>>; // { dg-error "here" "" { target c++17 } } +bool B16 = ratio_greater_equal_v, Ratty<16>>; // { dg-error "here" "" { target c++17 } } +#endif + +// { dg-error "static assertion failed" "" { target *-*-* } 0 }