[GHC] #15539: Regression since 7.10.3, "variable not in scope" errors sometimes get buried under a sea of much less relevant errors.

[GHC]

#15539: Regression since 7.10.3, "variable not in scope" errors sometimes get
buried under a sea of much less relevant errors.
-------------------------------------+-------------------------------------
        Reporter:  Wizek             |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
                                     |  rename/should_fail/T15539
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by simonpj):

 * status:  new => closed
 * testcase:   => rename/should_fail/T15539
 * resolution:   => fixed


Comment:

 Good point, thank you.  An oversight in `TcErrors`.

 (The bug only shows up for top level errors.  If you say even this:
 {{{
 foo :: forall b. String
 foo = show a
   where a = baz
 }}}
 which puts the `Show a` constrain under an implication, then the error is
 suppressed already. It just wasn't happening for constraints that had no
 enclosing implication.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15539#comment:2>
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