[commit: ghc] wip/T10180: exprIsBottom should look through type lambdas (6ab5bc4)

[git at git.haskell.org]

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

On branch  : wip/T10180
Link       : http://ghc.haskell.org/trac/ghc/changeset/6ab5bc4ca9b3afb5862079cd8e3922fdd8cbf1ff/ghc

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

commit 6ab5bc4ca9b3afb5862079cd8e3922fdd8cbf1ff
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Mon Mar 23 10:17:25 2015 +0100

    exprIsBottom should look through type lambdas
    
    as evaluting (\ (@ a) -> e) diverges if and only if evaluating e
    diverges. This was found in the context of #10180.


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6ab5bc4ca9b3afb5862079cd8e3922fdd8cbf1ff
 compiler/coreSyn/CoreUtils.hs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/compiler/coreSyn/CoreUtils.hs b/compiler/coreSyn/CoreUtils.hs
index 08f4fcd..b385576 100644
--- a/compiler/coreSyn/CoreUtils.hs
+++ b/compiler/coreSyn/CoreUtils.hs
@@ -702,6 +702,7 @@ exprIsBottom e
     go n (Tick _ e)              = go n e
     go n (Cast e _)              = go n e
     go n (Let _ e)               = go n e
+    go n (Lam v e) | isTyVar v   = go n e
     go _ _                       = False
 
 {-