Notes about tests:
- tests/ui/parser/macro/trait-object-macro-matcher.rs: the syntax error
is duplicated, because it occurs now when parsing the decl macro
input, and also when parsing the expanded decl macro. But this won't
show up for normal users due to error de-duplication.
- tests/ui/associated-consts/issue-93835.rs: similar, plus there are
some additional errors about this very broken code.
- The changes to metavariable descriptions in #132629 are now visible in
error message for several tests.
76b04437be