More aggressive Given/Wanted overlap check
authorSimon Peyton Jones <simonpj@microsoft.com>
Tue, 7 Apr 2015 13:29:10 +0000 (14:29 +0100)
committerSimon Peyton Jones <simonpj@microsoft.com>
Tue, 7 Apr 2015 14:10:45 +0000 (15:10 +0100)
commit8b7ceece52d2a0bb8a4ea5609da286fb76d88211
treeaf1d5ad801112ef703a4874f4f619e1dbaeb5158
parent6ca7b847ffc2c46b7fdde059bb57422354b3da89
More aggressive Given/Wanted overlap check

This fixes Trac #10195

For some reason we considered untouchability before, but Trac #10195
shows that this is positively worng.

See Note [Instance and Given overlap] in TcInteract.

Looking at the Git log, it seems that this bug was introduced at the
same time that we introduced the Given/Wanted overlap check in the first
place.
compiler/typecheck/TcInteract.hs
compiler/typecheck/TcType.hs
testsuite/tests/typecheck/should_compile/T10195.hs [new file with mode: 0644]
testsuite/tests/typecheck/should_compile/all.T