Compile failure on ubuntu 20.04 (gcc 9.4)

[rossburton]

When building fmt 11.1.1 and 11.1.2 on Ubuntu 20.04 (g++ 9.4.0), the tests fail:

FAILED: test/CMakeFiles/ostream-test.dir/ostream-test.cc.o
/BUILD/hosttools/g++ -DFMT_SHARED -DGTEST_HAS_STD_WSTRING=1 -D_SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING=1 -I/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include -isystem /BUILD/work/x86_64-linux/fmt-native/11.1.2/git/test/gtest/. -isystem/BUILD/work/x86_64-linux/fmt-native/11.1.2/recipe-sysroot-native/usr/include -O2 -pipe -fvisibility-inlines-hidden -DNDEBUG -fvisibility=hidden -fvisibility-inlines-hidden -MD -MT test/CMakeFiles/ostream-test.dir/ostream-test.cc.o -MF test/CMakeFiles/ostream-test.dir/ostream-test.cc.o.d -o test/CMakeFiles/ostream-test.dir/ostream-test.cc.o -c /BUILD/work/x86_64-linux/fmt-native/11.1.2/git/test/ostream-test.cc
In file included from /BUILD/work/x86_64-linux/fmt-native/11.1.2/git/test/ostream-test.cc:10:
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h: In instantiation of ‘constexpr decltype (ctx.out()) fmt::v11::formatter<fmt::v11::detail::std_string_view<Char>, Char>::format(fmt::v11::detail::std_string_view<Char>, FormatContext&) const [with FormatContext = fmt::v11::context; Char = char; decltype (ctx.out()) = fmt::v11::basic_appender<char>]’:
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/base.h:1126:54:   required by substitution of ‘template<class Char, class T, class U> decltype ((fmt::v11::formatter<U, Char>().format((* p), (* ctx)), std::true_type())) fmt::v11::detail::has_formatter_impl(T*, fmt::v11::buffered_context<Char>*) [with Char = char; T = fmt::v11::detail::std_string_view<char>; U = fmt::v11::detail::std_string_view<char>]’
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/base.h:1131:43:   required from ‘constexpr bool fmt::v11::detail::has_formatter() [with T = fmt::v11::detail::std_string_view<char>; Char = char]’
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/base.h:1187:62:   required by substitution of ‘template<bool B, class T, class F> using conditional_t = typename std::conditional::type [with bool B = fmt::v11::detail::has_formatter<fmt::v11::detail::std_string_view<char>, char>(); T = fmt::v11::detail::std_string_view<char>&; F = void]’
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/base.h:1187:15:   required by substitution of ‘template<class T, typename std::enable_if<fmt::v11::detail::use_formatter<T, typename std::remove_const<_Tp>::type>::value, int>::type <anonymous> > static fmt::v11::conditional_t<has_formatter<T, char>(), T&, void> fmt::v11::detail::type_mapper<char>::map<T, <enumerator> >(T&) [with T = fmt::v11::detail::std_string_view<char>; typename std::enable_if<fmt::v11::detail::use_formatter<T, typename std::remove_const<_Tp>::type>::value, int>::type <anonymous> = 0]’
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/base.h:1195:57:   required by substitution of ‘template<class T, class Char> using is_formattable = fmt::v11::bool_constant<(! std::is_same<decltype (fmt::v11::detail::type_mapper<Char>::map(declval<typename std::conditional<std::is_void<_Tp>::value, int*, T>::type&>())), void>::value)> [with T = fmt::v11::detail::std_string_view<char>; Char = char]’
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/test/ostream-test.cc:273:3:   required from here
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h:3764:43: error: no matching function for call to ‘fmt::v11::formatter<fmt::v11::detail::std_string_view<char>, char, void>::format(fmt::v11::detail::std_string_view<char>&, fmt::v11::context&) const’
 3764 |       return formatter<Base, Char>::format(value, ctx);             \
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h:3775:1: note: in expansion of macro ‘FMT_FORMAT_AS’
 3775 | FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
      | ^~~~~~~~~~~~~
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h:3632:20: note: candidate: ‘template<class FormatContext> constexpr decltype (ctx.out()) fmt::v11::detail::native_formatter<T, Char, TYPE>::format(const T&, FormatContext&) const [with FormatContext = FormatContext; T = fmt::v11::basic_string_view<char>; Char = char; fmt::v11::detail::type TYPE = fmt::v11::detail::type::string_type]’
 3632 | FMT_CONSTEXPR auto native_formatter<T, Char, TYPE>::format(
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h:3632:20: note:   template argument deduction/substitution failed:
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h:3764:44: note:   cannot convert ‘value’ (type ‘fmt::v11::detail::std_string_view<char>’) to type ‘const fmt::v11::basic_string_view<char>&’
 3764 |       return formatter<Base, Char>::format(value, ctx);             \
      |                                            ^~~~~
/BUILD/work/x86_64-linux/fmt-native/11.1.2/git/include/fmt/format.h:3775:1: note: in expansion of macro ‘FMT_FORMAT_AS’
 3775 | FMT_FORMAT_AS(detail::std_string_view<Char>, basic_string_view<Char>);
      | ^~~~~~~~~~~~~
ninja: build stopped: subcommand failed.

[vitaut]

Fixed in 5f0572a, thanks for reporting.

[vitaut]

Will include the fix in the upcoming patch release since it seems important.