[commit: ghc] ghc-8.4: Look inside implications in simplifyRule (d3573e4)

[git at git.haskell.org]

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

On branch  : ghc-8.4
Link       : http://ghc.haskell.org/trac/ghc/changeset/d3573e4ae63d6ae1ac0cd4bf5692a9bcd39ba733/ghc

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

commit d3573e4ae63d6ae1ac0cd4bf5692a9bcd39ba733
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Wed Jan 31 14:25:50 2018 +0000

    Look inside implications in simplifyRule
    
    Trac #14732 was a perpelexing bug in which -fdefer-typed-holes
    caused a mysterious type error in a RULE.  This turned out to
    be because we are more aggressive about creating implications
    when deferring (see TcUnify.implicationNeeded), and the rule
    mechanism hadn't caught up.
    
    This fixes it.
    
    (cherry picked from commit e9ae0cae9eb6a340473b339b5711ae76c6bdd045)


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d3573e4ae63d6ae1ac0cd4bf5692a9bcd39ba733
 compiler/typecheck/TcRules.hs                      | 105 +++++++++++++++------
 testsuite/tests/typecheck/should_compile/T14732.hs |  34 +++++++
 testsuite/tests/typecheck/should_compile/all.T     |   1 +
 3 files changed, 109 insertions(+), 31 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 d3573e4ae63d6ae1ac0cd4bf5692a9bcd39ba733