Fixes rust-lang#66898

When we are unable to resolve a reference to `self`, we current assume
that the containing function doesn't have a `self` parameter, and
emit an error message accordingly.

However, if the reference to `self` was created by a macro invocation,
then resolution will correctly fail, due to hygiene. In this case, we
don't want to tell the user that the containing fuction doesn't have a
'self' paramter if it actually has one.

This PR checks for the precense of a 'self' parameter, and adjusts the
error message we emit accordingly.

TODO: The exact error message we emit could probably be improved. Should
we explicitly mention hygiene?

exhaustively check `ty::Kind` during structural match checking

This was prone to errors as we may forget new kinds in the future.

I am also not yet sure about some kinds.

`ty::GeneratorWitness(..) | ty::Infer(_) | ty::Placeholder(_) | ty::UnnormalizedProjection(..)  | ty::Bound(..)` might be unreachable here.

We may want to forbid `ty::Projection`, similar to `ty::Param`.

`ty::Opaque` seems fine afaict, should not be possible in a match atm.

I believe `ty::Foreign` should not be structurally match, as I don't even know what
that would actually mean.

r? @pnkfelix cc @eddyb

…, r=matthewjasper

Emit a better diagnostic when function actually has a 'self' parameter

Fixes rust-lang#66898

When we are unable to resolve a reference to `self`, we current assume
that the containing function doesn't have a `self` parameter, and
emit an error message accordingly.

However, if the reference to `self` was created by a macro invocation,
then resolution will correctly fail, due to hygiene. In this case, we
don't want to tell the user that the containing fuction doesn't have a
'self' paramter if it actually has one.

This PR checks for the precense of a 'self' parameter, and adjusts the
error message we emit accordingly.

TODO: The exact error message we emit could probably be improved. Should
we explicitly mention hygiene?

Enable `glacier` command via triagebot

I noticed this was required by rust-lang#72554 (comment).

…an-DPC

Clean up E0608 explanation

r? @Dylan-DPC