[commit: ghc] wip/T12618: Fix calculation of res_ty in CoreFVs (d136b6b)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/T12618
Link       : http://ghc.haskell.org/trac/ghc/changeset/d136b6b84fc769e0c34c802b7125f90cf2de6c51/ghc

>---------------------------------------------------------------

commit d136b6b84fc769e0c34c802b7125f90cf2de6c51
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Fri Oct 21 15:13:43 2016 -0400

    Fix calculation of res_ty in CoreFVs
    
    but should the other code not have worked? Weird.


>---------------------------------------------------------------

d136b6b84fc769e0c34c802b7125f90cf2de6c51
 compiler/coreSyn/CoreFVs.hs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/compiler/coreSyn/CoreFVs.hs b/compiler/coreSyn/CoreFVs.hs
index dc46280..12544b8 100644
--- a/compiler/coreSyn/CoreFVs.hs
+++ b/compiler/coreSyn/CoreFVs.hs
@@ -753,9 +753,12 @@ freeVars = go
       where
         cargs'   = map go cargs
         args     = uncompressArgs exprTypeFV (go . Type) dc_ty cargs'
-        arg_tys  = map (exprToType . deAnnotate) args
         dc_ty    = dataConRepType dc
-        res_ty   = piResultTys dc_ty arg_tys
+        res_ty   = foldl applyTypeToArg dc_ty (map deAnnotate args)
+        -- Why does this not work? Isn't piResultTys just iterated application
+        -- of piResultTy, which is what applyTypeToArg uses?
+        -- arg_tys  = map (exprToType . deAnnotate) args
+        -- res_ty   = piResultTys dc_ty arg_tys
 
     go (Case scrut bndr ty alts)
       = ( FVAnn { fva_fvs = (bndr `delBinderFV` alts_fvs)