type_of metafunction should dealias the type

[changkhothuychung]

Fix #91

Issue number of the reported bug or feature request: #

Describe your changes
Adding code to dealias the underlying type in case of using typedef-name

Testing performed
Updating current tests in libcxx to reflect the new expected behaviors.

Additional context

[changkhothuychung]

Hi @katzdm , can you help me take a look when you have time?

[katzdm]

I probably should have pointed to this earlier, but this is the spec for type_of:
https://brevzin.github.io/cpp_proposals/2996_reflection/d2996r6.html#pnum_210

type_of(^^int) fails to be a constant expression, so the existing behavior (i.e., diagnosing an error) is correct.

The cases that need modification are Object, Value, Declaration, BaseSpecifier, and DataMemberSpec.

(also for return_type_of below)

Ping me tomorrow if there's anything I can help with!

[katzdm]

Out of curiosity, what happens if we just pass /*UnwrapAliases=*/true unconditionally? Are we avoiding an undesirable behavior with this check, or is this an optimization? If the later, I'd prefer passing unconditional true.

(also for return_type_of below)

[changkhothuychung]

I updated to unconditional true and it looks fine to me. I updated some tests in libcxx to reflect the new behavior.

[changkhothuychung]

I have this test fails locally - std/experimental/reflection/module-imports.sh.cpp

The reason is probably due to the arch of my laptop (mac M1). From the log - # error "We don't know how to get the definition of mbstate_t without <wchar.h> on your platform."

Can you help me run that test with my change to see if that runs ok?

[katzdm]

I have this test fails locally - std/experimental/reflection/module-imports.sh.cpp

The reason is probably due to the arch of my laptop (mac M1). From the log - # error "We don't know how to get the definition of mbstate_t without <wchar.h> on your platform."

Can you help me run that test with my change to see if that runs ok?

@changkhothuychung I believe I fixed this yesterday evening, while merging latest changes from upstream. Let me know if pulling from latest fixes the issue for you.