[GHC] #10283: Make it possible to suppress warnings produced by -fdefer-type-errors

[GHC]

#10283: Make it possible to suppress warnings produced by -fdefer-type-errors
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        Reporter:  adamgundry        |                   Owner:  kanetw
            Type:  feature request   |                  Status:  patch
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler (Type    |                 Version:  7.10.1
  checker)                           |                Keywords:  newcomer
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D864
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"f753cf11eb9e310b54b08d9a1ea1d11540d8eb69/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="f753cf11eb9e310b54b08d9a1ea1d11540d8eb69"
 Allow deferred type error warnings to be suppressed

 Adds a flag -fwarn-deferred-type-errors similar to -fwarn-typed-holes.
 Changes the boolean flag of -fdefer-type-errors to a 3-state flag
 similar to the one used by -fdefer-typed-holes/-fwarn-typed-holes.

 Test Plan: Since only the absence of deferred type error warnings when
 -fno-warn-deferred-type-errors is passed has to be tested, I duplicated
 a test case checking -fdefer-type-errors and adjusted it accordingly.

 Reviewers: nomeata, simonpj, austin, thomie, bgamari, hvr

 Reviewed By: nomeata, simonpj, austin, thomie, bgamari, hvr

 Subscribers: bgamari, simonpj, nomeata, thomie

 Projects: #ghc

 Differential Revision: https://phabricator.haskell.org/D864

 GHC Trac Issues: #10283
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10283#comment:9>
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