std::source_location line number wrong when used as default argument value

[IGR2014]

Consider the following code snipet (CompilerExplorer link):

#include<source_location>
#include<iostream>

void test_source_location(std::source_location src = std::source_location::current()) {
    std::cout << "called at " << src.line() << "\n";
}

int main() {
    test_source_location();
}

The output results for Clang, GCC and MSVC (left-to-right) are:

As you can see - both GCC and MSVC reports function INVOCATION line number, while Clang report function DECLARATION-one

[llvmbot]

@llvm/issue-subscribers-c-20

[ilya-biryukov]

I will take look at this

[aasimon]

I would love to help out on this task if I can. So let me know if there is anything I could do to help.

[ilya-biryukov]

Progress update from me.
I have a half-working fix (D129488), but it breaks consteval functions (see comments).
@jacobsa was about to pick it up from there.

[ilya-biryukov]

@aasimon we'll let you know if we don't make progress here, so you can pick it up.
Unless you feel really strongly about taking this over.

[aasimon]

@aasimon we'll let you know if we don't make progress here, so you can pick it up. Unless you feel really strongly about taking this over.

I hardly think I am qualified for taking over the task ;-) I was more referring to helping out with testing and such.