[commit: ghc] master: Fix #11974 by adding a more smarts to TcDefaults. (9a34bf1)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/9a34bf1985035858ece043bf38b47b6ff4b88efb/ghc

>---------------------------------------------------------------

commit 9a34bf1985035858ece043bf38b47b6ff4b88efb
Author: Richard Eisenberg <eir at cis.upenn.edu>
Date:   Fri Apr 22 22:28:35 2016 -0400

    Fix #11974 by adding a more smarts to TcDefaults.
    
    Test cases:
      typecheck/should_compile/T11974
      typecheck/should_fail/T11974b


>---------------------------------------------------------------

9a34bf1985035858ece043bf38b47b6ff4b88efb
 compiler/prelude/PrelNames.hs                      | 12 +++++++
 compiler/typecheck/TcDefaults.hs                   | 37 ++++++++++++----------
 compiler/typecheck/TcSimplify.hs                   |  2 +-
 testsuite/tests/typecheck/should_compile/T11974.hs |  5 +++
 testsuite/tests/typecheck/should_compile/all.T     |  1 +
 testsuite/tests/typecheck/should_fail/T11974b.hs   |  7 ++++
 .../tests/typecheck/should_fail/T11974b.stderr     | 15 +++++++++
 testsuite/tests/typecheck/should_fail/all.T        |  1 +
 8 files changed, 62 insertions(+), 18 deletions(-)

Diff suppressed because of size. To see it, use:

    git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc 9a34bf1985035858ece043bf38b47b6ff4b88efb