January 2016 - ghc-tickets

[GHC] #10289: compiling huge HashSet hogs memory
by GHC 05 Feb '16

05 Feb '16

#10289: compiling huge HashSet hogs memory -------------------------------------+------------------------------------- Reporter: zudov | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Runtime (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Compiling a huge (~2.5k elements) set with GHC-7.10.1 or GHC-head and unordered-containers-0.2.5.1 or unordered-containers-head takes way too much memory. Here is a [https://github.com/zudov/html5-entity/blob/unordered- containers/src/Text/Html/Entity/Data/EntitySet.hs file] which I am trying to compile. I've also set up a [https://travis- ci.org/zudov/html5-entity/builds/58063328 travis build] which demonstrates the behaviour with different versions of GHC and unordered-containers. Further I would be referring to [https://travis- ci.org/zudov/html5-entity/jobs/58063332 this build-job] which uses GHC-7.10.1 and unordered-containers-0.2.5.1. * [https://travis-ci.org/zudov/html5-entity/jobs/58063332#L397 Compilation] with default optimization options takes around [https ://travis-ci.org/zudov/html5-entity/jobs/58063332#L408 12GB] of memory. * [https://travis-ci.org/zudov/html5-entity/jobs/58063332#L367 Compilation] with `-O0` takes around [https://travis- ci.org/zudov/html5-entity/jobs/58063332#L378 400MB]. * [https://travis-ci.org/zudov/html5-entity/jobs/58063332#L457 Compilation] with `-O2` takes around [https://travis- ci.org/zudov/html5-entity/jobs/58063332#L468 12GB] of memory. * [https://travis-ci.org/zudov/html5-entity/jobs/58063332#L487 Compilation] with `-O2 -fignore-interface-pragmas` takes around [https ://travis-ci.org/zudov/html5-entity/jobs/58063332#L498 500MB] of memory, which solves the problem. When the build uses GHC-7.8.4, neither of this hogging [https://travis- ci.org/zudov/html5-entity/jobs/58063330 occurs]. Another interesting observation is that [https://travis- ci.org/zudov/html5-entity/jobs/58063330#L339 compiling] [https://github.com/zudov/html5-entity/blob/unordered- containers/src/Text/Html/Entity/Data/EntityMap.hs HashMap] of the same size, doesn't cause memory hogging even with `-O2`. This attracted my attention as `HashSet` is implemented in terms of `HashMap`. I reported the issue to `unordered-containers` as well: [https://github.com/tibbe/unordered-containers/issues/100 link]. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10289> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 11

[GHC] #9638: Speed up Data.Char.isDigit
by GHC 05 Feb '16

05 Feb '16

#9638: Speed up Data.Char.isDigit -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 | Type of failure: Runtime hour) | performance bug Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- `isDigit` is currently defined like this: {{{#!hs isDigit :: Char -> Bool isDigit c = c >= '0' && c <= '9' }}} This will short-circuit the right way if you're looking for digits mixed with spaces, but the wrong way if you're looking for digits mixed with letters. It also requires a conditional jump to do that short-circuiting (confirmed by inspecting the assembly). It should be better to use an unsigned comparison instead: {{{#!hs isDigit :: Char -> Bool isDigit c = (fromIntegral (ord c) :: Word) - 48 <= 9 }}} The interesting section looks like this {{{ movq 7(%rbx),%rax addq $-48,%rax cmpq $9,%rax setbe %al movzbl %al,%eax shlq $3,%rax movq ghczmprim_GHCziTypes_Bool_closure_tbl(%rax),%rbx addq $8,%rbp jmp *(%rbp) }}} or like this with -fllvm: {{{ movq 7(%rbx), %rax addq $-48, %rax cmpq $10, %rax sbbq %rax, %rax andq $8, %rax movq ghczmprim_GHCziTypes_Bool_closure_tbl(%rax), %rbx movq 8(%rbp), %rax addq $8, %rbp jmpq *%rax # TAILCALL }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9638> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 10

[GHC] #11374: `-Woverlapping-patterns` induced memory-blowup
by GHC 04 Feb '16

04 Feb '16

#11374: `-Woverlapping-patterns` induced memory-blowup -------------------------------------+------------------------------------- Reporter: hvr | Owner: gkaracha Type: bug | Status: new Priority: highest | Milestone: 8.0.1 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: -------------------------------------+------------------------------------- I'm afraid I've found yet another case that still let's the pattern checker go crazy (courtesy of hackage:cryptol-2.2.5): {{{#!hs {-# LANGUAGE Haskell2010 #-} {-# OPTIONS_GHC -Woverlapping-patterns #-} module Bug where data Type = TCon TCon [Type] | TUser String [Type] Type | TRec [(String,Type)] deriving (Show,Eq,Ord) data TCon = TC TC | TF TFun deriving (Show,Eq,Ord) data TC = TCNum Integer | TCInf | TCBit | TCSeq | TCFun | TCTuple Int deriving (Show,Eq,Ord) data TFun = TCAdd | TCSub | TCMul | TCDiv | TCMod | TCLg2 | TCExp | TCWidth | TCMin | TCMax | TCLenFromThen | TCLenFromThenTo deriving (Show, Eq, Ord, Bounded, Enum) simpFinTy :: Type -> Maybe [Type] simpFinTy ty = case ty of TCon (TC (TCNum _)) _ -> Just [] TCon (TF tf) [t1] | TCLg2 <- tf -> Just [t1] | TCWidth <- tf -> Just [t1] TCon (TF tf) [t1,t2] | TCAdd <- tf -> Just [t1, t2] | TCSub <- tf -> Just [t1] | TCMul <- tf -> Just [t1, t2] | TCDiv <- tf -> Just [t1] | TCMod <- tf -> Just [] | TCExp <- tf -> Just [t1, t2] | TCMin <- tf -> Nothing | TCMax <- tf -> Just [t1, t2] TCon (TF tf) [_,_,_] | TCLenFromThen <- tf -> Just [] | TCLenFromThenTo <- tf -> Just [] _ -> Nothing }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11374> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 6

[GHC] #11276: GHC hangs/takes an exponential amount of time with simple program
by GHC 04 Feb '16

04 Feb '16

#11276: GHC hangs/takes an exponential amount of time with simple program -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.10.3 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 was discovered when trying to compile xml-conduit. Here is the standalone test case with a few comments indicating how to make it compile. The program compiles with ghc-7.10.2 but fails with HEAD. {{{#!hs {-# LANGUAGE RankNTypes #-} module Hang where import Control.Monad import Data.Char data Event = EventBeginDocument | EventEndDocument | EventBeginDoctype | EventEndDoctype | EventInstruction | EventBeginElement | EventEndElement | EventContent Content | EventComment | EventCDATA data Content = ContentText String | ContentEntity String peek :: Monad m => Consumer a m (Maybe a) peek = undefined type Consumer i m r = forall o. ConduitM i o m r tag :: forall m a b c o . Monad m => ConduitM Event o m (Maybe c) tag = do _ <- dropWS return undefined where -- Add this and it works -- dropWS :: Monad m => ConduitM Event o m (Maybe Event) dropWS = do -- Swap these two lines and it works -- let x = undefined x <- peek let isWS = case x of -- Remove some of these and it works Just EventBeginDocument -> True Just EventEndDocument -> True Just EventBeginDoctype{} -> True Just EventEndDoctype -> True Just EventInstruction{} -> True Just EventBeginElement{} -> False Just EventEndElement{} -> False Just (EventContent (ContentText t)) | all isSpace t -> True | otherwise -> False Just (EventContent ContentEntity{}) -> False Just EventComment{} -> True Just EventCDATA{} -> False Nothing -> False if isWS then dropWS else return x -- Inlined Instances instance Functor (ConduitM i o m) where fmap f (ConduitM c) = ConduitM $ \rest -> c (rest . f) instance Applicative (ConduitM i o m) where pure x = ConduitM ($ x) {-# INLINE pure #-} (<*>) = ap {-# INLINE (<*>) #-} instance Monad (ConduitM i o m) where return = pure ConduitM f >>= g = ConduitM $ \h -> f $ \a -> unConduitM (g a) h instance Monad m => Functor (Pipe l i o u m) where fmap = liftM {-# INLINE fmap #-} instance Monad m => Applicative (Pipe l i o u m) where pure = Done {-# INLINE pure #-} (<*>) = ap {-# INLINE (<*>) #-} instance Monad m => Monad (Pipe l i o u m) where return = pure {-# INLINE return #-} HaveOutput p c o >>= fp = HaveOutput (p >>= fp) c o NeedInput p c >>= fp = NeedInput (p >=> fp) (c >=> fp) Done x >>= fp = fp x PipeM mp >>= fp = PipeM ((>>= fp) `liftM` mp) Leftover p i >>= fp = Leftover (p >>= fp) i newtype ConduitM i o m r = ConduitM { unConduitM :: forall b. (r -> Pipe i i o () m b) -> Pipe i i o () m b } data Pipe l i o u m r = HaveOutput (Pipe l i o u m r) (m ()) o | NeedInput (i -> Pipe l i o u m r) (u -> Pipe l i o u m r) | Done r | PipeM (m (Pipe l i o u m r)) | Leftover (Pipe l i o u m r) l }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11276> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 20

[GHC] #10284: Create a dedicated `TypeError` exception type
by GHC 03 Feb '16

03 Feb '16

#10284: Create a dedicated `TypeError` exception type -------------------------------------+------------------------------------- Reporter: kosmikus | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Ticket #10283 discusses using `-fdefer-type-errors` to test that certain programs do not type check. In practice, this involves evaluating certain expressions to WHNF at run- time can checking whether they trigger an exception. Currently, it seems the exception to catch is an `ErrorCall` exception. It would be nice if we could very specifically catch type errors though. It's entirely possible that a critical test case that I want to be a type error mistakenly type- checks and then calls `error`. In such a situation, it's hard to distinguish such a true run-time error from a deferred type error. It would be much nicer if something like `TypeError` would be thrown instead of `ErrorCall`. Yes, it's currently possible to look at the text of the `ErrorCall` and check for certain text fragments in there, but that sounds extremely fragile to me. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10284> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 13

[GHC] #10345: Testsuite timeout_multiplier setting does not work as expected
by GHC 03 Feb '16

03 Feb '16

#10345: Testsuite timeout_multiplier setting does not work as expected -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I have a test case that - if failed - sends GHC into an infinite loop. The test case is small so I don't want to wait for default timeout (currently that's 5 minutes). The testsuite provides `timeout_multiplier` function to modify the default timeout but that setting seems to be ignored and the test is killed only after the default timeout time. I added my test to `all.T` file like this: {{{ test('tc265', timeout_multiplier(0.01), compile, ['']) }}} I also tried putting timeout setting into an array (`[timeout_multiplier(0.01)]`) but with no result. Merijn reports having same problems and bypassing them by writing a test that forks itself and kills the child process after a given timeout - see [[GhcFile(libraries/base/tests/T8089.hs)]]. I am adding a note on [[wiki:Building/RunningTests/Adding#Thesetupfield]] that this field does not work currently. Once this bug is fixed we need to remove that note. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10345> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 11

[GHC] #8746: Crosscompiling
by GHC 02 Feb '16

02 Feb '16

#8746: Crosscompiling -------------------------------------+------------------------------------- Reporter: Visionstar | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Compiler | Version: 7.8.1-rc1 Keywords: Crosscompile | Operating System: Linux cross compile failed ncurses | Type of failure: Building GHC setupterm not found | failed Architecture: Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -------------------------------------+------------------------------------- Hello! I tried to crosscompile from linux i386 to arm-linux-gnueabihf, but i cant make it happen, because it gives me this weird error while running 'make': {{{ checking ncurses.h usability... yes checking ncurses.h presence... yes checking for ncurses.h... yes checking for setupterm in -ltinfo... no checking for setupterm in -lncursesw... no checking for setupterm in -lncurses... no checking for setupterm in -lcurses... no configure: error: in '/home/edi/ghc_cross/ghc/libraries/terminfo': configure: error: curses library not found, so this package cannot be built See 'config.log' for more details make[2]: *** [libraries/terminfo/dist-install/package-data.mk] Error 1 make[1]: *** [all_libraries/terminfo] Error 2 make[1]: Leave Directory '/home/edi/ghc_cross/ghc' make: *** [all] Error 2 }}} What have i done: -) Compiled 7.8.0 from github (The log says 'That should have been 7.8.0', i chose 7.8 because i thought it would be more stable for crosscompiling) to my i386 (normal boot, configure, make, make install). This worked fine -) installed newest llvm from svn (LLVM version 3.5svn) -) replaced the libffi-3.0.11.tar.gz in ghc/libffi-tarballs with libffi-3.0.13 -) added this version of mk/build.mk: {{{ SRC_HC_OPTS = -H32m _o -fasm -Rghc-timing GhcStage1HcOpts = -O -fasm GhcStage2HcOpts = -O0 -DDEBUG -Wall GhcLibHcOpts = -O -fasm -XGenerics GhcLibWays = v dyn SplitObjs = NO Stage1Only = YES }}} -) downloaded the sourcecode of ncurses from http://ftp.de.debian.org/debian/pool/main/n/ncurses/ncurses_5.9.orig.tar.gz and builded it with "./configure arm-linux-gnueabihf --with-gcc=arm-linux- gnueabihf-gcc --target=arm-linux-gnueabihf --prefix=/usr/arm-linux- gnueabihf " + "make". afterwards i added the folder to my $PATH -)did "perl boot", "./configure --target=arm-linux-gnueabihf --with-gcc =arm-linux-gnueabihf-gcc --prefix=/usr/arm-linux-gnueabihf" and "make". ./configure worked, but make gives me this weird error. I also tried copying all included files from ncurses to the libraries/terminfo folder, but that also didn't work. I think the mistake is somewhere in the building process, but i'm not exactly sure, so thats why i'm posting this bug. Does anyone have an idea about that? PS: i also made sure that i met the prerequirements mentioned in https://ghc.haskell.org/trac/ghc/wiki/Building/Preparation/Linux and https://ghc.haskell.org/trac/ghc/wiki/Building/CrossCompiling Greetings, Edi -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8746> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 7

[GHC] #11458: Terrible failure of type inference in visible type application
by GHC 02 Feb '16

02 Feb '16

#11458: Terrible failure of type inference in visible type application -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 7.10.3 (Type checker) | 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 {{{ -- optIntArg :: (Maybe Int -> t2) -> (t2,t2) optIntArg f = (f Nothing, f (Just True)) }}} This is rejected (by HEAD) {{{ T11379a.hs:5:30: error: * Couldn't match type `a' with `Bool' `a' is a rigid type variable bound by a type expected by the context: forall a. Maybe a at T11379a.hs:5:30 Expected type: forall a. Maybe a Actual type: Maybe Bool * In the first argument of `f', namely `(Just True)' In the expression: f (Just True) In the expression: (f Nothing, f (Just True)) }}} but if you put the tuple components the other way round, it works fine {{{ optIntArg f = (f (Just True), f Nothing) }}} Adding the commented-out signature also makes it work fine. I'm almost certain that this is caused by visible type application; perhaps `Nothing` gets delayed instantiation, and then `f`'s type becomes `forall a. Maybe a`. Utterly bogus. I suspect it'll be fixed by Richards `ReturnTv` work, but let's make sure it is. We can't release this!! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11458> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 6

[GHC] #11397: Type mismatch in local definitions in Haskell 98 code
by GHC 02 Feb '16

02 Feb '16

#11397: Type mismatch in local definitions in Haskell 98 code -------------------------------------+------------------------------------- Reporter: Lemming | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc1 (Type checker) | 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: -------------------------------------+------------------------------------- Here is the affected code with all package dependencies removes: {{{ $ cat PairMismatch.hs module PairMismatch (inverseFrequencyModulationChunk) where newtype VectorLazy a = VectorLazy a newtype Vector a = Vector a newtype Pointer a = Pointer a empty :: VectorLazy a empty = undefined cons :: Vector a -> Pointer a cons = undefined unfoldrResult :: (a -> Either c (b, a)) -> a -> (VectorLazy b, c) unfoldrResult = undefined switchL :: b -> (a -> Pointer a -> b) -> Pointer a -> b switchL = undefined inverseFrequencyModulationChunk :: (Num t, Ord t) => (s -> Maybe (t,s)) -> (t,s) -> Vector v -> (VectorLazy v, Maybe (t,s)) inverseFrequencyModulationChunk nextC (phase,cst0) chunk = let {- switch :: (Maybe (t, s) -> r) -> ((t, v) -> (s, Pointer v) -> r) -> t -> (s, Pointer v) -> r -} switch l r t (cp0,xp0) = maybe (l Nothing) (\(c1,cp1) -> switchL (l (Just (t,cp0))) (\x1 xp1 -> r (t+c1,x1) (cp1,xp1)) xp0) (nextC cp0) {- go :: (t,v) -> (s, Pointer v) -> Either (Maybe (t,s)) (v, ((t,v), (s, Pointer v))) -} go (c,x) cxp = if c<1 then switch Left go c cxp else Right (x, ((c-1,x),cxp)) in switch ((,) empty) (curry $ unfoldrResult (uncurry go)) phase (cst0, cons chunk) $ ghci-8.0.0.20160109 PairMismatch.hs GHCi, version 8.0.0.20160109: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling PairMismatch ( PairMismatch.hs, interpreted ) PairMismatch.hs:35:24: error: • Couldn't match type ‘a’ with ‘(t, s)’ ‘a’ is a rigid type variable bound by a type expected by the context: forall a. Maybe a at PairMismatch.hs:35:24 Expected type: forall a. Maybe a Actual type: Maybe (t, s) • In the first argument of ‘l’, namely ‘(Just (t, cp0))’ In the first argument of ‘switchL’, namely ‘(l (Just (t, cp0)))’ In the expression: switchL (l (Just (t, cp0))) (\ x1 xp1 -> r (t + c1, x1) (cp1, xp1)) xp0 • Relevant bindings include cp1 :: s (bound at PairMismatch.hs:33:20) c1 :: t (bound at PairMismatch.hs:33:17) cp0 :: s (bound at PairMismatch.hs:30:22) t :: t (bound at PairMismatch.hs:30:19) r :: (t, t1) -> (s, Pointer t1) -> b (bound at PairMismatch.hs:30:17) switch :: ((forall a. Maybe a) -> b) -> ((t, t1) -> (s, Pointer t1) -> b) -> t -> (s, Pointer t1) -> b (bound at PairMismatch.hs:30:8) inverseFrequencyModulationChunk :: (s -> Maybe (t, s)) -> (t, s) -> Vector v -> (VectorLazy v, Maybe (t, s)) (bound at PairMismatch.hs:22:1) (Some bindings suppressed; use -fmax-relevant-binds=N or -fno-max- relevant-binds) Failed, modules loaded: none. }}} It works with GHC-7.10.3 and before. I may try to further simplify the code and choose a better ticket header, if I got an idea what went wrong. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11397> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 8

[GHC] #11328: Auto complete in ghci shows $sel:function:Type for DuplicateRecordFields fields
by GHC 02 Feb '16

02 Feb '16

#11328: Auto complete in ghci shows $sel:function:Type for DuplicateRecordFields fields -------------------------------------+------------------------------------- Reporter: kolmodin | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 8.0.1-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: -------------------------------------+------------------------------------- Given a haskell file; {{{#!hs {-# LANGUAGE DuplicateRecordFields #-} -- t.hs data A = A { name :: String } data B = B { name :: String } }}} and in GHCi; {{{ ghci t.hs GHCi, version 8.1.20151231: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( tnum.hs, interpreted ) Ok, modules loaded: Main. *Main> <TAB> <TAB> ... $sel:name:A $sel:name:B ... }}} The records show up as `$sel:function:Type`, a function which you cannot refer to by name. Even if you enable `OverloadedLabels`, the `#labels` don't show up in the auto completion. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11328> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 7