Prevent users from defining instances for abstract classes.
authorEdward Z. Yang <ezyang@cs.stanford.edu>
Wed, 1 Mar 2017 08:11:43 +0000 (00:11 -0800)
committerEdward Z. Yang <ezyang@cs.stanford.edu>
Thu, 2 Mar 2017 23:59:02 +0000 (15:59 -0800)
commitbba004f2a0642d3bb8c8876543aaa1a48a2f9a43
treedbf421874c9e5ae537652851006c2b38144acd72
parentdf919fb21c951c1892bd96d9e6306ce1bec3daa9
Prevent users from defining instances for abstract classes.

Summary:
Fixes #13068.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>
Test Plan: validate

Reviewers: simonpj, austin, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D3254
compiler/typecheck/TcInstDcls.hs
compiler/types/Class.hs
testsuite/tests/typecheck/should_fail/T13068.hs [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/T13068.hs-boot [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/T13068.stderr [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/T13068a.hs [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/T13068m.hs [new file with mode: 0644]
testsuite/tests/typecheck/should_fail/all.T