[GHC] #9497: Silent typed holes

[GHC]

#9497: Silent typed holes
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              Reporter:  merijn      |            Owner:
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.8.3
             Component:  Compiler    |         Keywords:  typed holes,
            Resolution:              |  warnings
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by simonpj):

 I think that's a very reasonable suggestion.

 What would make sense to me is this:
  * `-XTypedHoles`, by default, generates ''warnings'' not ''errors''.

  * If you run a program that exhibits such warnings, you get the behaviour
 of `-fdefer-type-errors` (i.e. a runtime crash)

  * `-Werror` would make the warning into a fatal error, as usual.

  * We add a flag `-fno-warn-typed-holes` which switches off warnings if
 you don't want to see them.  This is the part you are asking for.

 By treating this as "just another warning", we make it less of a special
 case.

 However the first point is, I believe, a change in behaviour; i.e. it
 makes a typed hole into a non-fatal warning by default, rather than a
 fatal error.  To make it fatal you'd have to do `-Werror`, although that
 makes ''all'' warnings fatal.

 Does that seem like a reasonable change?

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9497#comment:1>
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