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[GHC] #13628: Confusing error message with TypeApplications already enabled
by GHC 28 Apr '17

28 Apr '17

#13628: Confusing error message with TypeApplications already enabled -------------------------------------+------------------------------------- Reporter: nh2 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I have `{-# LANGUAGE TypeApplications #-}` in my file, and accidentally wrote a typo: `myFunction@a` (missing space, intended was `myFunction @a`). GHC 8.0.2 outputs: {{{ Pattern syntax in expression context: myFunction@a Did you mean to enable TypeApplications? }}} I already have TypeApplications on, why does GHC suggest this? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13628> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11821: Internal error: not in scope during type checking, but it passed the renamer
by GHC 28 Apr '17

28 Apr '17

#11821: Internal error: not in scope during type checking, but it passed the renamer -------------------------------------+------------------------------------- Reporter: darchon | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 8.0.1-rc3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While trying to get the singletons package to compile on GHC8 (https://github.com/goldfirere/singletons/pull/142) I encountered the following error while trying to track down a bug: {{{ [1 of 1] Compiling NotInScope ( NotInScope.hs, interpreted ) NotInScope.hs:22:20: error: • GHC internal error: ‘b’ is not in scope during type checking, but it passed the renamer tcl_env of environment: [a1lm :-> Type variable ‘b’ = b, a1lA :-> Type variable ‘l1’ = l1, a1lB :-> Type variable ‘l2’ = l2, a1lC :-> Type variable ‘l3’ = l3, a1lE :-> Type variable ‘a’ = a, a1lF :-> Type variable ‘l4’ = l4, r1aq :-> ATcTyCon Lgo, r1aG :-> ATcTyCon Lgo1, r1aI :-> ATcTyCon Lgo2] • In the kind ‘b’ In the definition of data constructor ‘Lgo1KindInference’ In the data declaration for ‘Lgo1’ }}} for the following code: {{{ {-# LANGUAGE RankNTypes, DataKinds, PolyKinds, GADTs, TypeFamilies, UndecidableInstances #-} module NotInScope where import Data.Proxy type KindOf (a :: k) = ('KProxy :: KProxy k) data TyFun :: * -> * -> * type family Apply (f :: TyFun k1 k2 -> *) (x :: k1) :: k2 data Lgo2 l1 l2 l3 (l4 :: b) (l5 :: TyFun [a] b) = forall (arg :: [a]) . KindOf (Apply (Lgo2 l1 l2 l3 l4) arg) ~ KindOf (Lgo l1 l2 l3 l4 arg) => Lgo2KindInference data Lgo1 l1 l2 l3 (l4 :: TyFun b (TyFun [a] b -> *)) = forall (arg :: b) . KindOf (Apply (Lgo1 l1 l2 l3) arg) ~ KindOf (Lgo2 l1 l2 l3 arg) => Lgo1KindInference type family Lgo f z0 xs0 (a1 :: b) (a2 :: [a]) :: b where Lgo f z0 xs0 z '[] = z Lgo f z0 xs0 z ('(:) x xs) = Apply (Apply (Lgo1 f z0 xs0) (Apply (Apply f z) x)) xs }}} Note that the above code works fine in GHC 7.10.2. There are two options to make the code compile on GHC8-rc3: * Remove the kind annotations on the {{{forall arg .}}} binders * Or make the following changes using TypeInType: {{{ {-# LANGUAGE RankNTypes, DataKinds, PolyKinds, GADTs, TypeFamilies, UndecidableInstances, TypeInType #-} module NotInScope where import Data.Proxy import GHC.Types type KindOf (a :: k) = ('KProxy :: KProxy k) data TyFun :: * -> * -> * type family Apply (f :: TyFun k1 k2 -> *) (x :: k1) :: k2 data Lgo2 a b l1 l2 l3 (l4 :: b) (l5 :: TyFun [a] b) = forall (arg :: [a]) . KindOf (Apply (Lgo2 a b l1 l2 l3 l4) arg) ~ KindOf (Lgo a b l1 l2 l3 l4 arg) => Lgo2KindInference data Lgo1 a b l1 l2 l3 (l4 :: TyFun b (TyFun [a] b -> *)) = forall (arg :: b) . KindOf (Apply (Lgo1 a b l1 l2 l3) arg) ~ KindOf (Lgo2 a b l1 l2 l3 arg) => Lgo1KindInference type family Lgo a b f z0 xs0 (a1 :: b) (a2 :: [a]) :: b where Lgo a b f z0 xs0 z '[] = z Lgo a b f z0 xs0 z ('(:) x xs) = Apply (Apply (Lgo1 a b f z0 xs0) (Apply (Apply f z) x)) xs }}} I'm sorry I didn't create a smaller test case. Let me know if one is required and I'll try. The error seems to be related to the recursive aspect of the three definitions and how implicit kind variables are handled in ghc8. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11821> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13560: Windows binary distributions have absolute paths from the build environment in the `settings` file
by GHC 27 Apr '17

27 Apr '17

#13560: Windows binary distributions have absolute paths from the build environment in the `settings` file -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.2.1-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The GHC 8.2.1-rc1 binary distribution for Windows has the absolute path to `gcc` from the build environment in its `settings` file, {{{ ... ("C compiler command", "C:/msys64/home/drydock/bin- dist-8.2.0.20170404-MINGW64_NT-6.3/ghc/inplace/mingw/bin/gcc.exe"), ... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13560> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13611: Segfault due to levity polymorphism of mkWeak#
by GHC 27 Apr '17

27 Apr '17

#13611: Segfault due to levity polymorphism of mkWeak# -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This code segfaults: {{{ {-# LANGUAGE MagicHash, UnboxedTuples #-} import GHC.Prim import GHC.Types main = do let local = () let null = 0## :: Word# let triple = (# local, null, null #) IO (\s -> case mkWeakNoFinalizer# triple () s of (# s, r #) -> (# s, () #)) }}} The problem is that `mkWeakNoFinalizer#` has a levity polymorphic type for its first argument, but the implementation really requires the first argument to be a pointer. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13611> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13621: Problems with injective type families
by GHC 27 Apr '17

27 Apr '17

#13621: Problems with injective type families -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple InjectiveFamilies | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE GADTs, TypeInType, DataKinds, TypeFamilyDependencies #-} import Data.Kind type family IB a = res | res -> a where IB Int = Bool IB Bool = Int type Cat k = k -> k -> Type data F :: Cat Type where F :: (a -> IB a) -> F a (IB a) data Exp :: Type -> Type where I :: Int -> Exp Int B :: Bool -> Exp Bool fmap' :: F a b -> (Exp a -> Exp b) fmap' (F f) = \case B b -> I (f b) I i -> B (f i) }}} I would have thought this should work as well, given that `IB` is injective: {{{#!hs data F :: Cat Type where F :: (IB a -> a) -> F (IB a) a }}} but it gives {{{#!hs fmap' :: F a b -> (Exp a -> Exp b) fmap' (F f) = \case B b -> I (f b) -- c.hs:33:13: error: -- • Could not deduce: b ~ Int -- from the context: a ~ IB b -- bound by a pattern with constructor: -- F :: forall a. (IB a -> a) -> F (IB a) a, -- in an equation for ‘fmap'’ -- at c.hs:32:8-10 -- or from: a ~ Bool -- bound by a pattern with constructor: B :: Bool -> Exp Bool, -- in a case alternative -- at c.hs:33:3-5 -- ‘b’ is a rigid type variable bound by -- the type signature for: -- fmap' :: forall a b. F a b -> Exp a -> Exp b -- at c.hs:31:10 -- • In the first argument of ‘I’, namely ‘(f b)’ -- In the expression: I (f b) -- In a case alternative: B b -> I (f b) -- • Relevant bindings include -- f :: IB b -> b (bound at c.hs:32:10) -- fmap' :: F a b -> Exp a -> Exp b (bound at c.hs:32:1) -- Failed, modules loaded: none. }}} But if we know that `a ~ Bool` (as we do from matching on `B`), and we know that `a ~ IB b` then by injectivity it should figure that `b ~ Int`? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13621> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3781: Improve inlining for local functions
by GHC 27 Apr '17

27 Apr '17

#3781: Improve inlining for local functions -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 6.12.1 Resolution: | Keywords: Inlining Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): See also #3755, #7664 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3781#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13614: Rewrite rules not applied exhaustively when simplifying from plugin
by GHC 26 Apr '17

26 Apr '17

#13614: Rewrite rules not applied exhaustively when simplifying from plugin -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHC API | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider this program: {{{ {-# OPTIONS_GHC -O -fplugin TestPlugin #-} module Test where foo :: Int -> Int foo = id {-# INLINE [0] foo #-} {-# RULES "foo1" [1] foo 1 = foo 2 "foo2" [1] foo 2 = foo 3 #-} fun :: Int -> Int -> Int fun = (+) {-# NOINLINE fun #-} test = foo 1 `fun` foo 2 }}} I would expect that one run of the simplifier in phase `1` will turn this into {{{ test = foo 3 `fun` foo 3 }}} I am using this plugin to test this: {{{ module TestPlugin where import System.Exit import Control.Monad import GhcPlugins import Simplify import CoreStats import SimplMonad import FamInstEnv import SimplEnv -- Plugin boiler plate plugin :: Plugin plugin = defaultPlugin { installCoreToDos = install } install :: [CommandLineOption] -> [CoreToDo] -> CoreM [CoreToDo] install _ (simpl:xs) = return $ simpl : pass : xs where pass = CoreDoPluginPass "Test" testPass -- The plugin testPass :: ModGuts -> CoreM ModGuts testPass guts = do let [expr] = [ e | NonRec v e <- mg_binds guts , occNameString (occName v) == "test" ] simplified_expression <- simplify guts expr putMsg $ text "Test" $$ nest 4 (hang (text "Before" <> colon) 4 (ppr expr)) $$ nest 4 (hang (text "After" <> colon) 4 (ppr simplified_expression)) liftIO $ exitFailure -- A simplifier simplify :: ModGuts -> CoreExpr -> CoreM CoreExpr simplify guts expr = do dflags <- getDynFlags let dflags' = dflags { ufVeryAggressive = True } us <- liftIO $ mkSplitUniqSupply 's' let sz = exprSize expr rule_base <- getRuleBase vis_orphs <- getVisibleOrphanMods let rule_base2 = extendRuleBaseList rule_base (mg_rules guts) let rule_env = RuleEnv rule_base2 vis_orphs (expr', _) <- liftIO $ initSmpl dflags' rule_env emptyFamInstEnvs us sz $ simplExpr (simplEnv 1) >=> simplExpr (simplEnv 1) $ expr return expr' simplEnv :: Int -> SimplEnv simplEnv p = mkSimplEnv $ SimplMode { sm_names = ["Test"] , sm_phase = Phase p , sm_rules = True , sm_inline = True , sm_eta_expand = True , sm_case_case = True } }}} But I get: {{{ $ ghc-head -package ghc Test.hs [1 of 2] Compiling TestPlugin ( TestPlugin.hs, TestPlugin.o ) [2 of 2] Compiling Test ( Test.hs, Test.o ) Test Before: fun (foo (GHC.Types.I# 1#)) (foo (GHC.Types.I# 2#)) After: fun (foo (GHC.Types.I# 2#)) (foo (GHC.Types.I# 3#)) }}} If I however compile this without the plugin, and look at what’s happening with `-dverbose-core2core`, I observe this: {{{ … test :: Int test = fun (foo (GHC.Types.I# 1#)) (foo (GHC.Types.I# 2#)) … ==================== Simplifier ==================== Max iterations = 4 SimplMode {Phase = 1 [main], inline, rules, eta-expand, case-of-case} … test :: Int test = fun (foo (GHC.Types.I# 3#)) (foo (GHC.Types.I# 3#)) … }}} So what am I doing wrong in my plugin? Any help is appreciated. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13614> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13620: hsc2hs parses incorrectly '#ifdef' under '#{enum' in '--cross-compile' mode
by GHC 26 Apr '17

26 Apr '17

#13620: hsc2hs parses incorrectly '#ifdef' under '#{enum' in '--cross-compile' mode -------------------------------------+------------------------------------- Reporter: slyfox | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: hsc2hs | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The code is simplified version of something from Win32 package (https://github.com/haskell/win32/blob/master/System/Win32/SimpleMAPI.hsc#L56) {{{#!hs #{enum Int , , a = sizeof(int) #if 0 , b = sizeof(char) #endif } }}} {{{ $ hsc2hs b.hsc -o b.hs-native $ hsc2hs b.hsc -o b.hs-cross --cross-compile b.hsc:1 sizeof(int) #if 0 is not an integer }}} I'm not sure if it's a valid .hsc but having at least the same (valid or invalid) result in both modes would be nice. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13620> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13619: hsc2hs parses incorrectly c99 style ("/// ...") comments in '--cross-compile' mode
by GHC 26 Apr '17

26 Apr '17

#13619: hsc2hs parses incorrectly c99 style ("/// ...") comments in '--cross- compile' mode -------------------------------------+------------------------------------- Reporter: slyfox | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: hsc2hs | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The code is simplified version of something from Win32 package (https://github.com/haskell/win32/blob/master/Graphics/Win32/GDI/Pen.hsc#L59) {{{#!hs -- a.hsc #{enum Int , // "hi" there! , a = sizeof(int) } }}} {{{ $ hsc2hs a.hsc -o a.hs-cross --cross-compile $ hsc2hs a.hsc -o a.hs-native }}} {{{#!diff --- a.hs-cross 2017-04-26 21:56:56.157323964 +0100 +++ a.hs-native 2017-04-26 21:57:00.753311717 +0100 @@ -2,3 +2,3 @@ a :: Int -a = // "hi" there! 4 +a = 4 }}} I'm not sure if it's a valid .hsc but having at least the same (valid or invalid) result in both modes would be nice. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13619> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13616: Old file used when later calls to GHC omit -dynamic-too
by GHC 26 Apr '17

26 Apr '17

#13616: Old file used when later calls to GHC omit -dynamic-too -------------------------------------+------------------------------------- Reporter: nomeata | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This may possibly only hurt few people who develop Plugins, but it is still quite annoying: If `ghc`, in `--make` mode, recompiles a plugin that it is going to use, but without `-dynamic-too`, it will create new `.dyn` and `.o` files, but it will happily use the old `.dyn_hs` or `.dyn_o` files that are still lying around. I guess the desired behavior is: If it determines that it needs the dynamically compiled version of some module, and it is recompiling the module, then it should complain instead of later either ungracefully falling over the missing `.dyn_o` file or – worse – using an old one. This script reproduces the issue: {{{ #!/bin/bash rm -f *.o *.hi *.dyn_o *.dyn_hi cat > Plugin.hs <<__END__ module Plugin where import GhcPlugins plugin :: Plugin plugin = defaultPlugin { installCoreToDos = install } install :: [CommandLineOption] -> [CoreToDo] -> CoreM [CoreToDo] install _ _ = error "First version" __END__ cat > Code.hs <<__END__ {-# OPTIONS_GHC -O -fplugin Plugin #-} module Code where __END__ echo "No dynamic file found (fine, but the error message could be more helpful)" ghc -package ghc Code.hs -fforce-recomp echo "Compiling with -dynamic-too" ghc -dynamic-too -package ghc Code.hs -fforce-recomp cat > Plugin.hs <<__END__ module Plugin where import GhcPlugins plugin :: Plugin plugin = defaultPlugin { installCoreToDos = install } install :: [CommandLineOption] -> [CoreToDo] -> CoreM [CoreToDo] install _ _ = error "Second version" __END__ echo "Recompiling without -dynamic-too, it still uses the old file" ghc -package ghc Code.hs -fforce-recomp echo "Recompiling with -dynamic-too, now it works" ghc -dynamic-too -package ghc Code.hs -fforce-recomp }}} And here is the slightly redacted output: {{{ $ ./repro.sh No dynamic file found (fine, but the error message could be more helpful) [1 of 2] Compiling Plugin ( Plugin.hs, Plugin.o ) [2 of 2] Compiling Code ( Code.hs, Code.o ) <no location info>: fatal: cannot find object file ‘./Plugin.dyn_o’ while linking an interpreted expression Compiling with -dynamic-too [1 of 2] Compiling Plugin ( Plugin.hs, Plugin.o ) [2 of 2] Compiling Code ( Code.hs, Code.o ) ghc: panic! (the 'impossible' happened) First version Recompiling without -dynamic-too, it still uses the old file [1 of 2] Compiling Plugin ( Plugin.hs, Plugin.o ) [2 of 2] Compiling Code ( Code.hs, Code.o ) ghc: panic! (the 'impossible' happened) First version Recompiling with -dynamic-too, now it works [1 of 2] Compiling Plugin ( Plugin.hs, Plugin.o ) [2 of 2] Compiling Code ( Code.hs, Code.o ) ghc: panic! (the 'impossible' happened) Second version }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13616> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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