diff options
Diffstat (limited to 'compiler/GHC/Core/Rules.hs')
| -rw-r--r-- | compiler/GHC/Core/Rules.hs | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/compiler/GHC/Core/Rules.hs b/compiler/GHC/Core/Rules.hs index 451d1ac5c1..996764faa3 100644 --- a/compiler/GHC/Core/Rules.hs +++ b/compiler/GHC/Core/Rules.hs @@ -34,7 +34,7 @@ import GHC.Core -- All of it import GHC.Core.Subst import GHC.Core.SimpleOpt ( exprIsLambda_maybe ) import GHC.Core.FVs ( exprFreeVars, exprsFreeVars, bindFreeVars - , rulesFreeVarsDSet, exprsOrphNames, exprFreeVarsList ) + , rulesFreeVarsDSet, exprsOrphNames ) import GHC.Core.Utils ( exprType, mkTick, mkTicks , stripTicksTopT, stripTicksTopE , isJoinBind, mkCastMCo ) @@ -1223,7 +1223,9 @@ match_tmpl_var :: RuleMatchEnv match_tmpl_var renv@(RV { rv_lcl = rn_env, rv_fltR = flt_env }) subst@(RS { rs_id_subst = id_subst, rs_bndrs = let_bndrs }) v1' e2 - | any (inRnEnvR rn_env) (exprFreeVarsList e2) + -- anyInRnEnvR is lazy in the 2nd arg which allows us to avoid computing fvs + -- if the right side of the env is empty. + | anyInRnEnvR rn_env (exprFreeVars e2) = Nothing -- Skolem-escape failure -- e.g. match forall a. (\x-> a x) against (\y. y y) |