Should we add /D_USE_DETAILED_FUNCTION_NAME_IN_SOURCE_LOCATION=0 to one of PM_CL in usual_20_matrix.lst to test basic function names? is any PM_CL ok for that? After my current changes we test only detailed names.

We have so little test coverage of <source_location>, I think we should not modify the centralized matrices.

We should alter the specific test to provide coverage. (But I don't think we need to alter the modules and header units tests.)

By the way, how do you find out C1XX values in compile time?
I mean this:

#if !defined(__clang__) && !defined(__EDG__) // TRANSITION, VSO-1285783
    if (is_constant_evaluated()) {
        assert(s.x.loc.function_name() == "main"sv);
    } else
#endif // ^^^ workaround ^^^

How can we find "main"?
It's different from _EDG_ and C1XX in runtime, and you can't print it in compile time...
Error messages are not helpful either:

C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(320): error C2131: expression did not evaluate to a constant
C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(174): note: failure was caused by call of undefined function or one not declared 'constexpr'
C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(174): note: see usage of '_wassert'
C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(320): note: the call stack of the evaluation (the oldest call first) is
C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(320): note: while evaluating function 'bool test(void)'
C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(305): note: while evaluating function 'void sub_member_test(void)'
C:\Dev\STL\tests\std\tests\P1208R6_source_location\test.cpp(174): note: while evaluating function 'void _wassert(const wchar_t *,const wchar_t *,unsigned int)'

For _EDG_ I created a mini app and hover my mouse to variables to find out:

By the way, how do you find out C1XX values in compile time?

You preserve the compile time value until runtime where you can examine it. In this case, the function names all have static storage duration like string literals. You can simply return the value from the function to initialize a constinit const char* that you print in main: https://www.godbolt.org/z/jxj7PPofh.

Relabeling as this is a workaround removal in product code, purr! 😻

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

Thanks for the extensive workaround removal! 🧹 🪄 😺