[GHC] #8987: TH: panic in reportWarning when the message throws an exception

[GHC]

#8987: TH: panic in reportWarning when the message throws an exception
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        Reporter:  Yuras               |            Owner:
            Type:  bug                 |           Status:  new
        Priority:  normal              |        Milestone:
       Component:  Compiler            |          Version:  7.8.1
      Resolution:                      |         Keywords:
Operating System:  Unknown/Multiple    |     Architecture:
 Type of failure:  Compile-time crash  |  Unknown/Multiple
       Test Case:                      |       Difficulty:  Unknown
        Blocking:                      |       Blocked By:
                                       |  Related Tickets:
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Comment (by Yuras):

 Replying to [comment:2 simonpj]:
 > I have not thought about this deeply, but wouldn't something very
 similar happen with your change?  The program will still crash, won't it?

 No, ghc is prepared for exceptions in splice, including nested exceptions.
 See Note [Exceptions in TH] and Note [Concealed TH exceptions]
 So with my change compilation gracefully fails with the next message:

 {{{
 main.hs:1:1:
     Exception when trying to run compile-time code:
       Prelude.undefined
     Code: test
 }}}

 >
 > Would you like to give a test case?
 >
 > In any case, you are right that if you are going to do this at all, then
 something deepseq-like would be more thorough.
 >
 > By all means send a patch (with comments to explain).   Thanks.

 Well, looks like it is not possible to use `deepseq` in `ghc`. Should I
 implement ad-hoc solution? Something like `deepseqString`? I don't believe
 it is the first time we need `deepseq`, so most likely it is already
 implemented somewhere.

 Thanks,
 Yuras

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8987#comment:3>
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