[committed] libstdc++: Fix constraint on std::basic_format_string [PR108024]
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Commit Message
Tested x86_64-linux. Pushed to trunk.
-- >8--
Also remove some redundant std::move calls for return statements.
libstdc++-v3/ChangeLog:
PR libstdc++/108024
* include/std/format (basic_format_string): Fix constraint.
* testsuite/std/format/format_string.cc: New test.
---
libstdc++-v3/include/std/format | 10 ++++++----
.../testsuite/std/format/format_string.cc | 16 ++++++++++++++++
2 files changed, 22 insertions(+), 4 deletions(-)
create mode 100644 libstdc++-v3/testsuite/std/format/format_string.cc
@@ -110,7 +110,8 @@ namespace __format
template<typename _CharT, typename... _Args>
struct basic_format_string
{
- template<convertible_to<basic_string_view<_CharT>> _Tp>
+ template<typename _Tp>
+ requires convertible_to<const _Tp&, basic_string_view<_CharT>>
consteval
basic_format_string(const _Tp& __s);
@@ -609,7 +610,7 @@ namespace __format
else
for (_CharT __c : __str)
*__out++ = __c;
- return std::move(__out);
+ return __out;
}
// Write STR to OUT with NFILL copies of FILL_CHAR specified by ALIGN.
@@ -664,7 +665,7 @@ namespace __format
__out = __format::__write(std::move(__out), __str);
__pad(__r, __out);
- return std::move(__out);
+ return __out;
}
// A lightweight optional<locale>.
@@ -3626,7 +3627,8 @@ namespace __format
/// @endcond
template<typename _CharT, typename... _Args>
- template<convertible_to<basic_string_view<_CharT>> _Tp>
+ template<typename _Tp>
+ requires convertible_to<const _Tp&, basic_string_view<_CharT>>
consteval
basic_format_string<_CharT, _Args...>::
basic_format_string(const _Tp& __s)
new file mode 100644
@@ -0,0 +1,16 @@
+// { dg-options "-std=gnu++20" }
+// { dg-do compile { target c++20 } }
+
+#include <format>
+
+struct Str
+{
+ consteval operator std::string_view() const { return ""; }
+ operator std::string_view() = delete;
+};
+
+// PR libstdc++/108024
+static_assert( std::is_constructible_v<std::format_string<>, const Str&> );
+static_assert( std::is_convertible_v<const Str&, std::format_string<>> );
+
+constinit std::format_string<> s = Str();