[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 3 commits: Add missing addInScope call for letrec binders in OccurAnal
Marge Bot
gitlab at gitlab.haskell.org
Mon Apr 20 02:26:29 UTC 2020
Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC
Commits:
eaed0a32 by Alexis King at 2020-04-19T03:16:44-04:00
Add missing addInScope call for letrec binders in OccurAnal
This fixes #18044, where a shadowed variable was incorrectly substituted
by the binder swap on the RHS of a floated-in letrec. This can only
happen when the uniques line up *just* right, so writing a regression
test would be very difficult, but at least the fix is small and
straightforward.
- - - - -
ed8c86dc by Shayne Fletcher at 2020-04-19T22:26:21-04:00
Derive Ord instance for Extension
Metric Increase:
T12150
T12234
- - - - -
72fbb131 by Simon Peyton Jones at 2020-04-19T22:26:22-04:00
Fix a buglet in redundant-constraint warnings
Ticket #18036 pointed out that we were reporting a redundant
constraint when it really really wasn't.
Turned out to be a buglet in the SkolemInfo for the
relevant implication constraint. Easily fixed!
- - - - -
7 changed files:
- compiler/GHC/Core/Opt/OccurAnal.hs
- compiler/GHC/Tc/TyCl/Instance.hs
- libraries/ghc-boot-th/GHC/LanguageExtensions/Type.hs
- + testsuite/tests/typecheck/should_compile/T18036.hs
- + testsuite/tests/typecheck/should_compile/T18036a.hs
- + testsuite/tests/typecheck/should_compile/T18036a.stderr
- testsuite/tests/typecheck/should_compile/all.T
Changes:
=====================================
compiler/GHC/Core/Opt/OccurAnal.hs
=====================================
@@ -843,7 +843,7 @@ occAnalNonRecBind env lvl imp_rule_edges bndr rhs body_usage
occAnalRecBind :: OccEnv -> TopLevelFlag -> ImpRuleEdges -> [(Var,CoreExpr)]
-> UsageDetails -> (UsageDetails, [CoreBind])
occAnalRecBind env lvl imp_rule_edges pairs body_usage
- = foldr (occAnalRec env lvl) (body_usage, []) sccs
+ = foldr (occAnalRec rhs_env lvl) (body_usage, []) sccs
-- For a recursive group, we
-- * occ-analyse all the RHSs
-- * compute strongly-connected components
@@ -856,9 +856,11 @@ occAnalRecBind env lvl imp_rule_edges pairs body_usage
nodes :: [LetrecNode]
nodes = {-# SCC "occAnalBind.assoc" #-}
- map (makeNode env imp_rule_edges bndr_set) pairs
+ map (makeNode rhs_env imp_rule_edges bndr_set) pairs
- bndr_set = mkVarSet (map fst pairs)
+ bndrs = map fst pairs
+ bndr_set = mkVarSet bndrs
+ rhs_env = env `addInScope` bndrs
{-
Note [Unfoldings and join points]
=====================================
compiler/GHC/Tc/TyCl/Instance.hs
=====================================
@@ -1719,19 +1719,26 @@ tcMethodBodyHelp hs_sig_fn sel_id local_meth_id meth_bind
| Just hs_sig_ty <- hs_sig_fn sel_name
-- There is a signature in the instance
-- See Note [Instance method signatures]
- = do { let ctxt = FunSigCtxt sel_name True
- ; (sig_ty, hs_wrap)
+ = do { (sig_ty, hs_wrap)
<- setSrcSpan (getLoc (hsSigType hs_sig_ty)) $
do { inst_sigs <- xoptM LangExt.InstanceSigs
; checkTc inst_sigs (misplacedInstSig sel_name hs_sig_ty)
; sig_ty <- tcHsSigType (FunSigCtxt sel_name False) hs_sig_ty
; let local_meth_ty = idType local_meth_id
+ ctxt = FunSigCtxt sel_name False
+ -- False <=> do not report redundant constraints when
+ -- checking instance-sig <= class-meth-sig
+ -- The instance-sig is the focus here; the class-meth-sig
+ -- is fixed (#18036)
; hs_wrap <- addErrCtxtM (methSigCtxt sel_name sig_ty local_meth_ty) $
tcSubType_NC ctxt sig_ty local_meth_ty
; return (sig_ty, hs_wrap) }
; inner_meth_name <- newName (nameOccName sel_name)
- ; let inner_meth_id = mkLocalId inner_meth_name sig_ty
+ ; let ctxt = FunSigCtxt sel_name True
+ -- True <=> check for redundant constraints in the
+ -- user-specified instance signature
+ inner_meth_id = mkLocalId inner_meth_name sig_ty
inner_meth_sig = CompleteSig { sig_bndr = inner_meth_id
, sig_ctxt = ctxt
, sig_loc = getLoc (hsSigType hs_sig_ty) }
=====================================
libraries/ghc-boot-th/GHC/LanguageExtensions/Type.hs
=====================================
@@ -145,3 +145,7 @@ data Extension
| CUSKs
| StandaloneKindSignatures
deriving (Eq, Enum, Show, Generic, Bounded)
+-- 'Ord' and 'Bounded' are provided for GHC API users (see discussions
+-- in https://gitlab.haskell.org/ghc/ghc/merge_requests/2707 and
+-- https://gitlab.haskell.org/ghc/ghc/merge_requests/826).
+instance Ord Extension where compare a b = compare (fromEnum a) (fromEnum b)
=====================================
testsuite/tests/typecheck/should_compile/T18036.hs
=====================================
@@ -0,0 +1,13 @@
+{-# LANGUAGE InstanceSigs #-}
+{-# OPTIONS_GHC -Wredundant-constraints #-}
+
+module T18036 where
+
+class Fold f where
+ fold :: Monoid m => f m -> m
+
+newtype Identity a = Identity a
+
+instance Fold Identity where
+ fold :: Identity a -> a
+ fold (Identity a) = a
=====================================
testsuite/tests/typecheck/should_compile/T18036a.hs
=====================================
@@ -0,0 +1,15 @@
+{-# LANGUAGE InstanceSigs #-}
+{-# OPTIONS_GHC -Wredundant-constraints #-}
+
+module T18036 where
+
+class Fold f where
+ fold :: Monoid m => f m -> m
+
+newtype Identity a = Identity a
+
+-- Here we /should/ warn about redundant constraints in the
+-- instance signature, since we can remove them
+instance Fold Identity where
+ fold :: Monoid a => Identity a -> a
+ fold (Identity a) = a
=====================================
testsuite/tests/typecheck/should_compile/T18036a.stderr
=====================================
@@ -0,0 +1,6 @@
+
+T18036a.hs:14:13: warning: [-Wredundant-constraints]
+ • Redundant constraint: Monoid a
+ • In the type signature for:
+ fold :: forall a. Monoid a => Identity a -> a
+ In the instance declaration for ‘Fold Identity’
=====================================
testsuite/tests/typecheck/should_compile/all.T
=====================================
@@ -703,3 +703,5 @@ test('T17024', normal, compile, [''])
test('T17021a', normal, compile, [''])
test('T18005', normal, compile, [''])
test('T18023', normal, compile, [''])
+test('T18036', normal, compile, [''])
+test('T18036a', normal, compile, [''])
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b895317bff965a7f2aabc3bf83e118dff72b5fc0...72fbb1310056435e218e98c3f6875c93aa0a336d
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/b895317bff965a7f2aabc3bf83e118dff72b5fc0...72fbb1310056435e218e98c3f6875c93aa0a336d
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