[commit: ghc] ghc-8.2: Fix error-message suppress on given equalities (c9935f1)

[git at git.haskell.org]

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

On branch  : ghc-8.2
Link       : http://ghc.haskell.org/trac/ghc/changeset/c9935f1578369a8aa8243081873b706f7ff1b336/ghc

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

commit c9935f1578369a8aa8243081873b706f7ff1b336
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Mon Mar 27 10:32:08 2017 +0100

    Fix error-message suppress on given equalities
    
    I'd got the logic slightly wrong when reporting type errors
    for insoluble 'given' equalities.  We suppress insoluble givens
    under some circumstances (see Note [Given errors]), but we then
    suppressed subsequent 'wanted' errors because the (suppressed)
    'given' error "won".  Result: no errors at all :-(.
    
    This patch fixes it and
     - Renames TcType.isTyVarUnderDatatype to the more
       perspicuous TcType.isInsolubleOccursCheck
    
    In doing this I realise that I don't understand why we need
    to keep the insolubles partitioned out separately at all...
    but that is for another day.
    
    (cherry picked from commit e0ad55f894a8d85dcc099c33c63cfe3d4515d464)


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

c9935f1578369a8aa8243081873b706f7ff1b336
 compiler/typecheck/TcCanonical.hs                  |  9 +--
 compiler/typecheck/TcErrors.hs                     | 77 ++++++++++++++--------
 compiler/typecheck/TcType.hs                       | 45 ++++++++-----
 testsuite/tests/ghci/scripts/Defer02.stderr        |  5 ++
 .../tests/indexed-types/should_fail/T2627b.stderr  | 10 ++-
 .../tests/indexed-types/should_fail/T5934.stderr   | 18 ++++-
 .../tests/indexed-types/should_fail/T6123.stderr   |  3 +-
 .../tests/indexed-types/should_fail/T7354.stderr   |  5 +-
 .../tests/typecheck/should_compile/T12427a.stderr  | 21 +-----
 .../tests/typecheck/should_fail/T12589.stderr      |  9 +++
 testsuite/tests/typecheck/should_fail/T13446.hs    | 46 +++++++++++++
 .../tests/typecheck/should_fail/T13446.stderr      | 10 +++
 testsuite/tests/typecheck/should_fail/all.T        |  1 +
 13 files changed, 184 insertions(+), 75 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 c9935f1578369a8aa8243081873b706f7ff1b336