Don't report fundep wanted/wanted errors
authorSimon Peyton Jones <simonpj@microsoft.com>
Wed, 5 Apr 2017 12:37:28 +0000 (13:37 +0100)
committerSimon Peyton Jones <simonpj@microsoft.com>
Thu, 6 Apr 2017 11:33:48 +0000 (12:33 +0100)
commit48daaaf0bba279b6e362ee5c632de69ed31ab65d
tree2abcb500dae42efe75d8689a21623fd7957ae466
parentdd228b6eae18a05675b698fa309403d2310a269b
Don't report fundep wanted/wanted errors

This makes GHC drop derived FunDep errors when they
are come from wanted/wanted interactions.  Much along
the lines of "don't rewrite wanteds with wanteds".

See TcRnTypes Note [Dropping derived constraints]
and the new code in isDroppableDerivedLoc.

Fixes Trac #13506.
compiler/typecheck/TcRnTypes.hs
testsuite/tests/typecheck/should_fail/T13506.hs [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/T13506.stderr [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/all.T