Do not check synonym RHS for ambiguity
authorSimon Peyton Jones <simonpj@microsoft.com>
Mon, 29 Feb 2016 14:12:28 +0000 (14:12 +0000)
committerSimon Peyton Jones <simonpj@microsoft.com>
Tue, 1 Mar 2016 17:08:32 +0000 (17:08 +0000)
commit3c29c770be7a8c7268dcb8d8624853428aa42071
treeefccd6574fba20f01058b2d9a9aebe1e97b15d69
parent49c55e68aae9841c166430ae566b0d9bdc03c99d
Do not check synonym RHS for ambiguity

With this patch we no longer check the RHS of a type synonym
declaration for ambiguity.  It only affects type synonyms with foralls
on the RHS (which are rare in the first place), and it's arguably
over-aggressive to check them for ambiguity.  See TcValidity
Note [When we don't check for ambiguity]

This fixes the ASSERT failures in
   th                        T3100
   typecheck/should_compile  T3692
   typecheck/should_fail     T3592
compiler/typecheck/TcValidity.hs