Hi! Apparently clang trunk implemented __builtin_source_location(), but the using __builtin_ret_type = decltype(__builtin_source_location()); which has been added for it isn't enough, they also need the std::source_location::__impl class to be defined (but incomplete seems to be good enough) before the builtin is used.
The following has been tested on godbolt with clang trunk (old version fails with error: 'std::source_location::__impl' was not found; it must be defined before '__builtin_source_location' is called and some follow-up errors), getting back to just void * instead of __builtin_ret_type and commenting out using doesn't work either and just struct __impl; before using __builtin_ret_type doesn't work too. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2022-04-02 Jakub Jelinek <ja...@redhat.com> PR libstdc++/105128 * include/std/source_location (std::source_location::__impl): Move definition before using __builtin_ret_type. --- libstdc++-v3/include/std/source_location 2022-02-25 10:46:53.275178858 +0100 +++ libstdc++-v3/include/std/source_location 2022-04-01 19:36:02.056236397 +0200 @@ -43,6 +43,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { private: using uint_least32_t = __UINT_LEAST32_TYPE__; + struct __impl + { + const char* _M_file_name; + const char* _M_function_name; + unsigned _M_line; + unsigned _M_column; + }; using __builtin_ret_type = decltype(__builtin_source_location()); public: @@ -76,14 +83,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { return _M_impl ? _M_impl->_M_function_name : ""; } private: - struct __impl - { - const char* _M_file_name; - const char* _M_function_name; - unsigned _M_line; - unsigned _M_column; - }; - const __impl* _M_impl = nullptr; }; Jakub