Warn on inferred polymorphic recursion
Commit message
Warn on inferred polymorphic recursion
Silly users sometimes try to use visible dependent quantification
and polymorphic recursion without a CUSK or SAK. This causes
unexpected errors. So we now adjust expectations with a bit
of helpful messaging.
Closes #17541 and closes #17131.
test cases: dependent/should_fail/T{17541{,b},17131}
See also Note [Inferred visible dependent quantification] in TcTyClsDecls.
Tag #17541 (closed) and #17131 (closed).