[GHC] #12007: Panic when loading file with nested pattern synonyms into ghci

[GHC]

#12007: Panic when loading file with nested pattern synonyms into ghci
-------------------------------------+-------------------------------------
        Reporter:  MikeIzbicki       |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms
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 simonpj):

 I have learned a bit more.

 * Here is a smaller test case
 {{{
 pattern A a1 = a1
 pattern B a1 = A a1
 }}}

 * The bug is that `kindRep` falls over.  I'm pretty sure it's the call
 from `typePrimRep`.

 * The code spat out by `CorePrep` is absolutely fine.

 * The crash comes when the bytecode codegen gets hold of it.

 I wish I knew ''which'' call to `typePrimRep`  in the bytecode generator
 was causing the crash.  Maybe someone can try stack-tracing (with our new
 lightweight `CallStack` stuff) to narrow it down?

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12007#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler