id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
5458,Phantom types confuse SpecConstr,simonpj,,"This program
{{{
type T a = Int

f :: T a -> Bool -> [Int]
f x b = case b of
               True  -> f x b
               False -> x : f x (x > 19)
}}}
gave a Lint error in `SpecConstr` (use -O2).  Reason: the specialised function was abstracted over `x`, but x's type mentions a phantom type variable `a`, and that ''wasn't'' being abstracted over.

Phantom type variables are a nuisance.  A simple fix is to de-synonym the type of the abstracted variables.",bug,closed,normal,,Compiler,7.2.1,fixed,,,Unknown/Multiple,Unknown/Multiple,None/Unknown,,simplCore/should_compile/T5458,,,