Skip to content

Fix a bad error in tcMatchTy

Simon Peyton Jones requested to merge wip/T17395 into master

Fix a bad error in tcMatchTy

This patch fixes #17395 (closed), a very subtle and hard-to-trigger bug in tcMatchTy. It's all explained in Note [Matching in the presence of casts (2)]

I have not added a regression test because it is very hard to trigger it, until we have the upcoming mkAppTyM patch, after which lacking this patch means you can't even compile the libraries.

Merge request reports