|
|
Summary:
Previously, we tested for type synonym loops by doing
a syntactic test on the literal type synonym declarations.
However, in some cases, loops could go through hs-boot
files, leading to an infinite loop (#12042); a similar
situation can occur when signature merging.
This commit replaces the syntactic test with a test on
TyCon, simply by walking down all type synonyms until
we bottom out, or find we've looped back. It's a lot
simpler.
Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>
Test Plan: validate
Reviewers: simonpj, austin, bgamari
Subscribers: goldfire, thomie
Differential Revision: https://phabricator.haskell.org/D2656
GHC Trac Issues: #12042
|
