diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format index 961441e355b37d06b003cbea245c178b21f4efc9..ee189f9086ce9451a71a8bcd800604776d0b0003 100644 --- a/libstdc++-v3/include/std/format +++ b/libstdc++-v3/include/std/format @@ -3210,7 +3210,7 @@ namespace __format // Format as const if possible, to reduce instantiations. template<typename _Tp> using __maybe_const_t - = __conditional_t<__formattable<_Tp>, const _Tp, _Tp>; + = __conditional_t<__formattable<const _Tp>, const _Tp, _Tp>; template<typename _Tq> static void @@ -3228,10 +3228,6 @@ namespace __format explicit handle(_Tp& __val) noexcept { - if constexpr (!__formattable<const _Tp>) - static_assert(!is_const_v<_Tp>, "std::format argument must be " - "non-const for this type"); - this->_M_ptr = __builtin_addressof(__val); auto __func = _S_format<__maybe_const_t<_Tp>>; this->_M_func = reinterpret_cast<void(*)()>(__func); diff --git a/libstdc++-v3/testsuite/std/format/formatter/basic.cc b/libstdc++-v3/testsuite/std/format/formatter/basic.cc new file mode 100644 index 0000000000000000000000000000000000000000..56c18864135af4ca1561bf175d122d8fa8dc2eec --- /dev/null +++ b/libstdc++-v3/testsuite/std/format/formatter/basic.cc @@ -0,0 +1,24 @@ +// { dg-do compile { target c++20 } } + +// BasicFormatter requirements do not require a const parameter. + +#include <format> + +struct X { }; + +template<> struct std::formatter<X, char> +{ + constexpr auto parse(format_parse_context& ctx) + { return ctx.begin(); } + + // Takes non-const X& + format_context::iterator format(X&, format_context& ctx) const + { + auto out = ctx.out(); + *out++ = 'x'; + return out; + } +}; + +X x; +auto s = std::format("{}", x);