diff --git a/compiler/deSugar/Match.lhs b/compiler/deSugar/Match.lhs index 0433d873d55addcf2139ea3910faad59cd117d1c..e0a5d4af0cc6908367eecf6a3781b46daf7ee4c0 100644 --- a/compiler/deSugar/Match.lhs +++ b/compiler/deSugar/Match.lhs @@ -586,8 +586,6 @@ tidy1 _ non_interesting_pat -------------------- tidy_bang_pat :: Id -> SrcSpan -> Pat Id -> DsM (DsWrapper, Pat Id) --- BangPatterns: Pattern matching is already strict in constructors, --- tuples etc, so the last case strips off the bang for those patterns. -- Discard bang around strict pattern tidy_bang_pat v _ p@(ListPat {}) = tidy1 v p @@ -596,8 +594,7 @@ tidy_bang_pat v _ p@(PArrPat {}) = tidy1 v p tidy_bang_pat v _ p@(ConPatOut {}) = tidy1 v p tidy_bang_pat v _ p@(LitPat {}) = tidy1 v p --- Discard lazy/par/sig under a bang -tidy_bang_pat v _ (LazyPat (L l p)) = tidy_bang_pat v l p +-- Discard par/sig under a bang tidy_bang_pat v _ (ParPat (L l p)) = tidy_bang_pat v l p tidy_bang_pat v _ (SigPatOut (L l p) _) = tidy_bang_pat v l p @@ -607,7 +604,10 @@ tidy_bang_pat v l (AsPat v' p) = tidy1 v (AsPat v' (L l (BangPat p))) tidy_bang_pat v l (CoPat w p t) = tidy1 v (CoPat w (BangPat (L l p)) t) -- Default case, leave the bang there: --- VarPat, WildPat, ViewPat, NPat, NPlusKPat +-- VarPat, LazyPat, WildPat, ViewPat, NPat, NPlusKPat +-- For LazyPat, remember that it's semantically like a VarPat +-- i.e. !(~p) is not like ~p, or p! (Trac #8952) + tidy_bang_pat _ l p = return (idDsWrapper, BangPat (L l p)) -- NB: SigPatIn, ConPatIn should not happen \end{code} diff --git a/testsuite/tests/deSugar/should_run/T8952.hs b/testsuite/tests/deSugar/should_run/T8952.hs new file mode 100644 index 0000000000000000000000000000000000000000..42eeb250a9baea7412b2b1bfee2d7a9b43233d3e --- /dev/null +++ b/testsuite/tests/deSugar/should_run/T8952.hs @@ -0,0 +1,8 @@ +{-# LANGUAGE BangPatterns #-} + +module Main where + +main = print (case Nothing of + !(~(Just x)) -> "ok" + Nothing -> "bad") + diff --git a/testsuite/tests/deSugar/should_run/T8952.stdout b/testsuite/tests/deSugar/should_run/T8952.stdout new file mode 100644 index 0000000000000000000000000000000000000000..52c33a57c76fbc5dcd2fcd29a0a87afc97a02fee --- /dev/null +++ b/testsuite/tests/deSugar/should_run/T8952.stdout @@ -0,0 +1 @@ +"ok" diff --git a/testsuite/tests/deSugar/should_run/all.T b/testsuite/tests/deSugar/should_run/all.T index 352a65239eac59048755c423d5f579292efe66cc..233f6485d9c9cdf47c8597a786e0fc361e3c1c9c 100644 --- a/testsuite/tests/deSugar/should_run/all.T +++ b/testsuite/tests/deSugar/should_run/all.T @@ -40,3 +40,4 @@ test('mc08', normal, compile_and_run, ['']) test('T5742', normal, compile_and_run, ['']) test('DsLambdaCase', when(compiler_lt('ghc', '7.5'), skip), compile_and_run, ['']) test('DsMultiWayIf', when(compiler_lt('ghc', '7.5'), skip), compile_and_run, ['']) +test('T8952', normal, compile_and_run, [''])