[commit: ghc] master: COMPLETE pragmas for enhanced pattern exhaustiveness checking (1a3f1ee)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/1a3f1eebf81952accb6340252816211c7d391300/ghc

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

commit 1a3f1eebf81952accb6340252816211c7d391300
Author: Matthew Pickering <matthewtpickering at gmail.com>
Date:   Wed Jan 18 13:25:30 2017 +0000

    COMPLETE pragmas for enhanced pattern exhaustiveness checking
    
    This patch adds a new pragma so that users can specify `COMPLETE` sets of
    `ConLike`s in order to sate the pattern match checker.
    
    A function which matches on all the patterns in a complete grouping
    will not cause the exhaustiveness checker to emit warnings.
    
    ```
    pattern P :: ()
    pattern P = ()
    
    {-# COMPLETE P #-}
    
    foo P = ()
    ```
    
    This example would previously have caused the checker to warn that
    all cases were not matched even though matching on `P` is sufficient to
    make `foo` covering. With the addition of the pragma, the compiler
    will recognise that matching on `P` alone is enough and not emit
    any warnings.
    
    Reviewers: goldfire, gkaracha, alanz, austin, bgamari
    
    Reviewed By: alanz
    
    Subscribers: lelf, nomeata, gkaracha, thomie
    
    Differential Revision: https://phabricator.haskell.org/D2669
    
    GHC Trac Issues: #8779


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

1a3f1eebf81952accb6340252816211c7d391300
 compiler/basicTypes/ConLike.hs                     |   5 +
 compiler/deSugar/Check.hs                          | 276 ++++++++++++++-------
 compiler/deSugar/Desugar.hs                        |  14 +-
 compiler/deSugar/DsMeta.hs                         |   1 +
 compiler/deSugar/DsMonad.hs                        |  26 +-
 compiler/deSugar/PmExpr.hs                         |  57 +++--
 compiler/deSugar/TmOracle.hs                       |  13 +-
 compiler/hsSyn/HsBinds.hs                          |  13 +
 compiler/iface/IfaceSyn.hs                         |  10 +
 compiler/iface/MkIface.hs                          |  20 +-
 compiler/iface/TcIface.hs                          |  31 +++
 compiler/main/HscTypes.hs                          |  42 +++-
 compiler/main/TidyPgm.hs                           |   5 +-
 compiler/parser/Lexer.x                            |   7 +-
 compiler/parser/Parser.y                           |  13 +
 compiler/parser/RdrHsSyn.hs                        |   2 +-
 compiler/rename/RnBinds.hs                         |  10 +
 compiler/typecheck/TcBinds.hs                      | 107 +++++++-
 compiler/typecheck/TcRnDriver.hs                   |   2 +-
 compiler/typecheck/TcRnMonad.hs                    |   3 +-
 compiler/typecheck/TcRnTypes.hs                    |  24 +-
 compiler/vectorise/Vectorise/Monad.hs              |   2 +-
 docs/users_guide/glasgow_exts.rst                  |  78 ++++++
 .../tests/pmcheck/complete_sigs/Completesig03.hs   |   7 +
 .../pmcheck/complete_sigs/Completesig03.stderr     |   2 +
 .../tests/pmcheck/complete_sigs/Completesig03A.hs  |   5 +
 .../complete_sigs}/Makefile                        |   0
 testsuite/tests/pmcheck/complete_sigs/all.T        |  15 ++
 .../tests/pmcheck/complete_sigs/completesig01.hs   |  20 ++
 .../tests/pmcheck/complete_sigs/completesig02.hs   |  10 +
 .../pmcheck/complete_sigs/completesig02.stderr     |   4 +
 .../tests/pmcheck/complete_sigs/completesig04.hs   |   3 +
 .../pmcheck/complete_sigs/completesig04.stderr     |   4 +
 .../tests/pmcheck/complete_sigs/completesig05.hs   |  14 ++
 .../tests/pmcheck/complete_sigs/completesig06.hs   |  29 +++
 .../pmcheck/complete_sigs/completesig06.stderr     |  29 +++
 .../tests/pmcheck/complete_sigs/completesig07.hs   |  24 ++
 .../pmcheck/complete_sigs/completesig07.stderr     |  11 +
 .../tests/pmcheck/complete_sigs/completesig08.hs   |  30 +++
 .../tests/pmcheck/complete_sigs/completesig09.hs   |  13 +
 .../tests/pmcheck/complete_sigs/completesig10.hs   |  33 +++
 .../pmcheck/complete_sigs/completesig10.stderr     |   4 +
 .../tests/pmcheck/complete_sigs/completesig11.hs   |  14 ++
 .../pmcheck/complete_sigs/completesig11.stderr     |   4 +
 .../tests/pmcheck/complete_sigs/completesig12.hs   |  22 ++
 .../tests/pmcheck/complete_sigs/completesig13.hs   |  19 ++
 .../tests/pmcheck/complete_sigs/completesig14.hs   |  11 +
 .../pmcheck/complete_sigs/completesig14.stderr     |   4 +
 .../tests/pmcheck/complete_sigs/completesig15.hs   |  12 +
 .../pmcheck/complete_sigs/completesig15.stderr     |   4 +
 testsuite/tests/pmcheck/should_compile/all.T       |   2 +-
 51 files changed, 956 insertions(+), 154 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 1a3f1eebf81952accb6340252816211c7d391300