pdimov
commented
7 months ago I'm looking at this and wondering where we want to go with it.
Ideally, I'd like to make this macro the default argument of the source_location const* parameter everywhere. Not sure when, though.
Looking at the codegen, the first lambda path, the one passing the current location as an argument to the lambda, generates a guard variable. I don't see a way to avoid that, and for me, this kind of rules it out from being silently applied by default.
I suppose we could just use the other one, clearing the function name.
The Clang path seems a bit dubious; while clang-cl supports __builtin_source_location(), it doesn't work, because in the MS STL, std::source_location doesn't have an __impl member.
Also, Clang using libstdc++ would use its std::source_location, which would make __impl inaccessible, but the test doesn't seem to account for this, it only looks at the compiler.
If we consider the _PTR macro an implementation detail that's only used as a default argument, I think we can dispense with the type safety and just use an ordinary pointer.
Allows passing current location to error_code ctor without requiring a separate static local variable.
Implementation uses __builtin_source_location() on clang and gcc returning a pointer to std::source_location::__impl, which we verify is layout-compatible with boost::source_location.