[commit: ghc] master: Improve exhaustive checking for guards in pattern bindings and MultiIf. (e8e9f6a)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/e8e9f6a7a6d857efe6e3b2aec0c4964f9a8fa09a/ghc

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

commit e8e9f6a7a6d857efe6e3b2aec0c4964f9a8fa09a
Author: HE, Tao <sighingnow at gmail.com>
Date:   Fri Mar 2 14:16:24 2018 -0500

    Improve exhaustive checking for guards in pattern bindings and MultiIf.
    
    Previously we didn't do exhaustive checking on MultiIf expressions
    and guards in pattern bindings.
    
    We can construct the `LMatch` directly from GRHSs or [LHsExpr]
    (MultiIf's alts) then feed it to checkMatches, without construct the
    MatchGroup and using function `matchWrapper`.
    
    Signed-off-by: HE, Tao <sighingnow at gmail.com>
    
    Test Plan: make test TEST="T14773a T14773b"
    
    Reviewers: bgamari, RyanGlScott, simonpj
    
    Reviewed By: bgamari, simonpj
    
    Subscribers: rwbarton, thomie, carter
    
    GHC Trac Issues: #14773
    
    Differential Revision: https://phabricator.haskell.org/D4400


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

e8e9f6a7a6d857efe6e3b2aec0c4964f9a8fa09a
 compiler/deSugar/Check.hs                          | 24 +++++++++++++++---
 compiler/deSugar/DsBinds.hs                        |  2 ++
 compiler/deSugar/DsExpr.hs                         |  3 +++
 compiler/deSugar/DsGRHSs.hs                        |  3 +--
 compiler/hsSyn/HsExpr.hs                           | 29 ++++++++++++++--------
 docs/users_guide/8.6.1-notes.rst                   | 16 ++++++++++++
 testsuite/tests/deSugar/should_compile/T14773a.hs  | 10 ++++++++
 .../tests/deSugar/should_compile/T14773a.stderr    |  5 ++++
 testsuite/tests/deSugar/should_compile/T14773b.hs  |  8 ++++++
 .../tests/deSugar/should_compile/T14773b.stderr    |  5 ++++
 testsuite/tests/deSugar/should_compile/all.T       |  2 ++
 11 files changed, 91 insertions(+), 16 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 e8e9f6a7a6d857efe6e3b2aec0c4964f9a8fa09a