diff options
Diffstat (limited to 'compiler/simplCore/Simplify.hs')
| -rw-r--r-- | compiler/simplCore/Simplify.hs | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/compiler/simplCore/Simplify.hs b/compiler/simplCore/Simplify.hs index efefa23758..2e1dcefbdb 100644 --- a/compiler/simplCore/Simplify.hs +++ b/compiler/simplCore/Simplify.hs @@ -1179,11 +1179,15 @@ simplCast env body co0 cont0 -- But it isn't a common case. -- -- Example of use: Trac #995 - = do { (dup', arg_se', arg') <- simplArg env dup arg_se arg - ; cont' <- addCoerce co2 cont + = do { let arg' = substExprS arg_se arg + -- It's important that this is lazy, because this argument + -- may be disarded if turns out to be the argument of + -- (\_ -> e) This can make a huge difference; + -- see Trac #10527 + ; cont' <- addCoerce co2 cont ; return (ApplyToVal { sc_arg = mkCast arg' (mkSymCo co1) - , sc_env = arg_se' - , sc_dup = dup' + , sc_env = zapSubstEnv arg_se + , sc_dup = dup , sc_cont = cont' }) } where -- we split coercion t1->t2 ~ s1->s2 into t1 ~ s1 and |