When compiling the below source code


#include <string>

template <typename = void>
struct T {
    static constexpr std::string value{};
};

void f() {
    T<>::value;
}


the compiler fails on the line in f() with the following error referring to the members of the std::string being private:



<source>:5:34: error: 'std::__cxx11::basic_string<char>::<unnamed union> std::__cxx11::basic_string<char>::<anonymous>' is private within this context
    5 |     static constexpr std::string value{};
      |                                  ^~~~~
In file included from /cefs/b6/b615954805438726f22a60c9_converted_gcc-15.2.0/include/c++/15.2.0/string:56,
                 from <source>:1:
/cefs/b6/b615954805438726f22a60c9_converted_gcc-15.2.0/include/c++/15.2.0/bits/basic_string.h:220:7: note: declared private here
  220 |       union
      |       ^~~~~
<source>:5:34: error: 'char std::__cxx11::basic_string<char>::<unnamed union>::_M_local_buf [16]' is private within this context
    5 |     static constexpr std::string value{};
      |                                  ^~~~~
/cefs/b6/b615954805438726f22a60c9_converted_gcc-15.2.0/include/c++/15.2.0/bits/basic_string.h:222:26: note: declared private here
  222 |         _CharT           _M_local_buf[_S_local_capacity + 1];
      |                          ^~~~~~~~~~~~


The same code works fine in Clang. Checked with `-std=c++26`.


https://godbolt.org/z/844x68798