[commit: ghc] master: Test for type synonym loops on TyCon. (31398fb)

[git at git.haskell.org]

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

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/31398fbc6d9ee0bd95de64b08becc38faf188972/ghc

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

commit 31398fbc6d9ee0bd95de64b08becc38faf188972
Author: Edward Z. Yang <ezyang at cs.stanford.edu>
Date:   Fri Oct 28 17:54:36 2016 -0700

    Test for type synonym loops on TyCon.
    
    Summary:
    Previously, we tested for type synonym loops by doing
    a syntactic test on the literal type synonym declarations.
    However, in some cases, loops could go through hs-boot
    files, leading to an infinite loop (#12042); a similar
    situation can occur when signature merging.
    
    This commit replaces the syntactic test with a test on
    TyCon, simply by walking down all type synonyms until
    we bottom out, or find we've looped back.  It's a lot
    simpler.
    
    Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>
    
    Test Plan: validate
    
    Reviewers: simonpj, austin, bgamari
    
    Subscribers: goldfire, thomie
    
    Differential Revision: https://phabricator.haskell.org/D2656
    
    GHC Trac Issues: #12042


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31398fbc6d9ee0bd95de64b08becc38faf188972
 compiler/hsSyn/HsDecls.hs                          |    1 +
 compiler/typecheck/TcBackpack.hs                   |    4 +
 compiler/typecheck/TcBinds.hs                      |    4 +-
 compiler/typecheck/TcTyClsDecls.hs                 |  157 ++-
 compiler/typecheck/TcTyDecls.hs                    |  209 ++--
 compiler/types/Type.hs                             |    2 +
 docs/users_guide/8.2.1-notes.rst                   |   10 +
 docs/users_guide/glasgow_exts.rst                  |    4 +-
 testsuite/driver/extra_files.py                    |    1 +
 testsuite/tests/backpack/should_fail/all.T         |    1 +
 .../should_fail/{bkpfail04.bkp => bkpfail29.bkp}   |   12 +-
 .../tests/backpack/should_fail/bkpfail29.stderr    |   11 +
 testsuite/tests/module/mod27.stderr                |    2 +-
 testsuite/tests/typecheck/should_compile/all.T     |    3 +
 testsuite/tests/typecheck/should_compile/tc268.hs  |    5 +
 testsuite/tests/typecheck/should_compile/tc269.hs  |   22 +
 testsuite/tests/typecheck/should_compile/tc270.hs  | 1006 ++++++++++++++++++++
 testsuite/tests/typecheck/should_fail/T12042.hs    |    4 +
 .../tests/typecheck/should_fail/T12042.hs-boot     |    3 +
 .../tests/typecheck/should_fail/T12042.stderr      |    9 +
 testsuite/tests/typecheck/should_fail/T12042a.hs   |    3 +
 testsuite/tests/typecheck/should_fail/all.T        |    1 +
 22 files changed, 1321 insertions(+), 153 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 31398fbc6d9ee0bd95de64b08becc38faf188972