[GHC] #12184: unsafeCoerce# causing invalid assembly generation

[GHC]

#12184: unsafeCoerce# causing invalid assembly generation
-------------------------------------+-------------------------------------
        Reporter:  osa1              |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             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:                    |
-------------------------------------+-------------------------------------

Comment (by osa1):

 > you were lucky enough to get an error message

 But I did not get an error message! GHC is happily generating an assembly
 file with `naughty x86_64 register` in it! I think it should at least
 panic at that point instead of printing this. But ideally, the code
 generator would know more about the register set and do something sensible
 e.g. a proper error message ("unsafeCoerce# between float and int not
 supported as they live in separate registers" etc.).

 Really, I should be getting a panic.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12184#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler