[gcc r12-4455] libstdc++: Fix error in filesystem::path with Clang

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:e547d1341b1fe90672c9b982c4a98f8197237bb7

commit r12-4455-ge547d1341b1fe90672c9b982c4a98f8197237bb7
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Fri Oct 15 23:27:54 2021 +0100

    libstdc++: Fix error in filesystem::path with Clang
    
    THis fixes teh following error seen with Clang:
    
    error: function '_S_convert<std::basic_string_view<char8_t>>' with deduced
    return type cannot be used before it is defined
              return string_type(_S_convert(std::u8string_view(__str)));
                                 ^
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/fs_path.h (path::_S_convert(T)): Avoid recursive
            call to function with deduced return type.

Diff:
---
 libstdc++-v3/include/bits/fs_path.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/include/bits/fs_path.h b/libstdc++-v3/include/bits/fs_path.h
index d13fb12455c..4bd980952f1 100644
--- a/libstdc++-v3/include/bits/fs_path.h
+++ b/libstdc++-v3/include/bits/fs_path.h
@@ -630,7 +630,8 @@ namespace __detail
 	  // Calling _S_convert<char8_t> will return a u8string_view that
 	  // refers to __str and would dangle after this function returns.
 	  // Return a string_type instead, to avoid dangling.
-	  return string_type(_S_convert(std::u8string_view(__str)));
+	  return string_type(_S_convert(__str.data(),
+					__str.data() + __str.size()));
 #endif
 	else
 	  return _S_convert(__str.data(), __str.data() + __str.size());