[GHC] #11787: Infer HasCallStack where possible

[GHC]

#11787: Infer HasCallStack where possible
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        Reporter:  simonpj           |                Owner:  gridaphobe
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:  invalid           |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by simonpj):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 > we no longer infer CallStacks, period

 Oh yes, right! That makes this ticket redundant.

 > You seem to be suggesting that the fix for #11376 involves expanding
 type synonyms,

 Typechecking any expression, such as `(\x -> error x)` involves
 instantiating constraints, in this case the `HasCallStack` constraint from
 `error`.  Then we simplify and re-generalise.  It's that step that expands
 the synonym.

 Anyway, I'll close this as no-longer-relevant.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11787#comment:5>
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