libstdc++: Fix brainwrong in path::_S_convert(T) [PR102743]

This function was supposed to check whether the parameter's value type
is the same as path::value_type, and therefore needs no conversion.
Instead it checks whether the parameter is the same as its own value
type, which is never true. This means we incorrectly return a string
view for the case where T is path::string_type, instead of just
returning the string itself. The only place that happens is
path::_S_convert_loc for Windows, where we call _S_convert with a
std::wstring rvalue.

This fixes the condition in _S_convert(T).

libstdc++-v3/ChangeLog:

	PR libstdc++/102743
	* include/bits/fs_path.h (path::_S_convert(T)): Fix condition
	for returning the same string unchanged.

diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index c51bfa3..a63e4b9 100644 (file)
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -625,7 +625,7 @@ namespace __detail
       static auto
       _S_convert(_Tp __str)
       {
-       if constexpr (is_same_v<_Tp, typename _Tp::value_type>)
+       if constexpr (is_same_v<typename _Tp::value_type, value_type>)
          return __str; // No conversion needed.
 #if !defined _GLIBCXX_FILESYSTEM_IS_WINDOWS && defined _GLIBCXX_USE_CHAR8_T
        else if constexpr (is_same_v<_Tp, std::u8string>)