February 2016 - ghc-tickets

[GHC] #11531: ghci with ffi to inline assembly results in "the 'impossible'"
by GHC 03 Feb '16

03 Feb '16

#11531: ghci with ffi to inline assembly results in "the 'impossible'" --------------------------------------+--------------------------------- Reporter: isovector | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: ffi, asm, ghci | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+--------------------------------- I'm attempting to run some assembly in Haskell; in order to do that I wrote a FFI to some inline C asm. Attempting to load it in ghci results in: $ g++ -c ffi.cpp -fPIC $ ghci ffi.o Main.hs GHCi, version 7.8.4: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading object (static) ffi.o ... ghc: panic! (the 'impossible' happened) (GHC version 7.8.4 for x86_64-unknown-linux): Loading temp shared object failed: /tmp/ghc8684_0/ghc8684_1.so: undefined symbol: _ZNSt8ios_base4InitD1Ev Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug It said to report a bug, so here it is! -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11531> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)?
by GHC 03 Feb '16

03 Feb '16

#7450: Regression in optimisation time of functions with many patterns (6.12 to 7.4)? -------------------------------------+------------------------------------- Reporter: iustin | Owner: bgamari Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1012 Wiki Page: | -------------------------------------+------------------------------------- Changes (by HairyDude): * cc: HairyDude (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7450#comment:32> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[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

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Re: [GHC] #4505: Segmentation fault on long input (list of pairs)
by GHC 02 Feb '16

02 Feb '16

#4505: Segmentation fault on long input (list of pairs) -------------------------------------+------------------------------------- Reporter: cathper | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 7.0.1 Resolution: | Keywords: Segmentation | fault, segfault, long input Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Runtime crash | Test Case: Blocked By: 4258 | Blocking: Related Tickets: | Differential Rev(s): Phab:D1180 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * milestone: 8.0.1 => 8.2.1 Comment: Punting to 8.2. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4505#comment:43> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[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

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[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

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[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

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[GHC] #11428: ImpredicativeTypes causes GHC panic with 8.0.1-rc1
by GHC 02 Feb '16

02 Feb '16

#11428: ImpredicativeTypes causes GHC panic with 8.0.1-rc1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.0.1-rc1 (Type checker) | Keywords: | Operating System: Unknown/Multiple ImpredicativeTypes | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I noticed this issue when attempting to compile `conduit` with GHC 8.0.1-rc1 (specifically, the [https://github.com/snoyberg/conduit/blob/master/conduit/Data/Conduit/Intern… Data.Conduit.Internal.Pipe] module). This (greatly simplified) code, which compiles without issue on GHC 7.10.3: {{{#!hs {-# LANGUAGE ImpredicativeTypes #-} module Data.Conduit.Internal.Pipe where data Pipe o r = HaveOutput (Pipe o r) o mapOutputMaybe :: (o1 -> Maybe o2) -> Pipe o1 r -> Pipe o2 r mapOutputMaybe f (HaveOutput p o) = maybe id (\o' p' -> HaveOutput p' o') (f o) (mapOutputMaybe f p) }}} emits a GHC panic with GHC 8.0.1-rc1: {{{ [1 of 1] Compiling Data.Conduit.Internal.Pipe ( Wat.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.0.20160111 for x86_64-unknown-linux): matchExpectedFunTys <> a_a15Z[tau:5] -> b_a15Y[tau:5] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Note that this code does not require `-XImpredicativeTypes`, and removing the pragma makes the code compile again. Marking as high since it's a regression, but not highest because `-XImpredicativeTypes` has long been broken (see also #11319). Still, this currently happens on code in the wild, and perhaps it would be worth turning this into a more sensible error. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11428> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11247: Weird error from running runghc on an invalid input filename
by GHC 02 Feb '16

02 Feb '16

#11247: Weird error from running runghc on an invalid input filename -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #7765 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I had files `random.hs` and `random.hi` and `random.o`, so I accidentally entered the following command with tab completion. {{{ rwbarton@morphism:/tmp$ runghc random. Warning: ignoring unrecognised input `random.' random.:1:33: Not in scope: ‘main’ Perhaps you meant ‘min’ (imported from Prelude) }}} #7765 is surely related, but with HEAD (well, rather old, but at least new enough to contain the fix for #7765), the error is not really any better: {{{ rwbarton@morphism:/tmp$ ~/ghc/inplace/bin/runghc random. Warning: ignoring unrecognised input `random.' random.:0:53: error: Variable not in scope: main :: IO a0 Perhaps you meant ‘min’ (imported from Prelude) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11247> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11487: stg_ap_pp_fast doesn't pass the argument in the arity=1 case
by GHC 02 Feb '16

02 Feb '16

#11487: stg_ap_pp_fast doesn't pass the argument in the arity=1 case --------------------------------------+---------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.1 Component: Runtime System | Version: 8.0.1-rc1 Keywords: | Operating System: Linux Architecture: arm | Type of failure: Runtime crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------------+---------------------------------- The body of `stg_ap_pp_fast` looks like {{{ arity = TO_W_(StgFunInfoExtra_arity(%GET_FUN_INFO(R1))); ASSERT(arity > 0); if (arity == 1) { Sp_adj(-2); W_[Sp+WDS(1)] = R3; W_[Sp+WDS(0)] = stg_ap_p_info; R1 = R1 + 1; jump_SAVE_CCCS(%GET_ENTRY(UNTAG(R1))); } if (arity == 2) { Sp_adj(0); R1 = R1 + 2; jump %GET_ENTRY(UNTAG(R1)) [R1,R2,R3]; } else { Sp_adj(-3); W_[Sp+WDS(2)] = R3; W_[Sp+WDS(1)] = R2; if (arity < 4) { R1 = R1 + arity; } BUILD_PAP(2,2,stg_ap_pp_info,FUN); } }}} where {{{ // Jump to target, saving CCCS and restoring it on return #if defined(PROFILING) #define jump_SAVE_CCCS(target) \ Sp(-1) = CCCS; \ Sp(-2) = stg_restore_cccs_info; \ Sp_adj(-2); \ jump (target) [R1] #else #define jump_SAVE_CCCS(target) jump (target) [R1] #endif }}} So in the arity=1 case the jump amounts to {{{ jump (%GET_ENTRY(UNTAG(R1))) [R1] }}} R1 is the function to apply, but we don't pass its argument, R2! Now, possibly by design, the calling convention of `stg_ap_pp_fast` is such that the first argument to apply is in R2, which is the same register that the function R1 will expect to find its argument in. So if nothing happens to disturb R2 (and possibly this is always the case with the NCG), then everything is fine. However, it's definitely not fine for the LLVM backend, which quite reasonably passes `undef` for the R2, R3, and R4 arguments when doing the jump. On arm/Android, LLVM decided to clobber `r8` (the physical register for R2) in the body of `stg_ap_pp_fast`. This caused a crash for the following program: {{{ main = print (read "3"::Int) }}} This appears to have been broken by commit f9265dd369b9e269349930012c25e670248f2a09 which changed the argument list for `jump_SAVE_CCCS` from `[*]` to `[R1]`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11487> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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