November 2015 - ghc-tickets

[GHC] #11039: Panic with incorrect pattern synonym signature
by GHC 23 Dec '15

23 Dec '15

#11039: Panic with incorrect pattern synonym signature -------------------------------------+------------------------------------- Reporter: mpickering | Owner: Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 7.11 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: -------------------------------------+------------------------------------- {{{ {-# LANGUAGE PatternSynonyms #-} module Foo () where data A a = A a pattern Q :: () => (A ~ f) => a -> f a pattern Q a = A a }}} error with HEAD {{{ poly-export2.hs:7:9: error:ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20151030 for x86_64-apple-darwin): No skolem info: f_amp[sk] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11039> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10897: Incorrect ASSERT for buildPatSyn
by GHC 23 Dec '15

23 Dec '15

#10897: Incorrect ASSERT for buildPatSyn -------------------------------------+------------------------------------- Reporter: ezyang | Owner: cactus Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Consider the following two files: {{{ -- A.hs {-# LANGUAGE PatternSynonyms #-} module A where pattern Single :: a -> a pattern Single x = x -- B.hs module B where import A Single y = True }}} When I build these using one-shot compilation using a debugged GHC (i.e. with ASSERTs) I get the following error: {{{ [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c A.hs -fforce-recomp [ezyang@hs01 ghc-quick3]$ inplace/bin/ghc-stage2 -c B.hs -fforce-recomp ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150918 for x86_64-unknown-linux): ASSERT failed! file compiler/iface/BuildTyCl.hs, line 210 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I expanded the assert and discovered it was claiming the universal type variables of the matcher should be equal to the type variables of the pattern declaration. This assert cannot possibly be right: the matcher and the pattern declaration are typechecked separately and there's no reason that the local binders should actually be the same. The equality test here should be done up to alpha-renaming. The other thing I found a bit puzzling was whether or not it mattered whether or not we used the local type variables from the matcher or the freshly bound ones. I suppose if we are consistent it shouldn't matter, so I don't think the code is buggy, just a bad ASSERT. BTW: this assert problem doesn't show up with `--make` because the assert occurs during typechecking of interface files, and with `--make` we don't need to typecheck an interface file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10897> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11137: configure is broken for the unix package
by GHC 23 Dec '15

23 Dec '15

#11137: configure is broken for the unix package -------------------------------------+------------------------------------- Reporter: pgj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.11 libraries/unix | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- A few weeks ago (around November 1, 2015), the FreeBSD builders started to fail building GHC-HEAD with an error message something like that: {{{ [...] /usr/home/ghc-builder/work/builder/tempbuild/build/libraries/unix/dist- install/build/libHSunix-2.7.1.0-ghc7.11.20151126.so: undefined reference to `fdatasync' collect2: error: ld returned 1 exit status `gcc48' failed in phase `Linker'. (Exit code: 1) ghc/ghc.mk:121: recipe for target 'ghc/stage2/build/tmp/ghc-stage2' failed gmake[1]: *** [ghc/stage2/build/tmp/ghc-stage2] Error 1 Makefile:121: recipe for target 'all' failed gmake: *** [all] Error 2 }}} That is because {{{fdatasync(2)}}} is not implemented on FreeBSD. Apparently, it is handled in the respective file ({{{System/Posix/Unistd.hsc}}}), though it relies on the variable ({{{HAVE_FDATASYNC}}}) generated at the {{{configure}}} phase. But for some reason, the {{{configure}}} script of the {{{unix}}} package fails to detect this as it says the following: {{{ "inplace/bin/ghc-cabal" configure libraries/unix dist-install "" --with- ghc="/usr/home/ghc-builder/work/builder/tempbuild/build/inplace/bin/ghc- stage1" --with-ghc-pkg="/usr/home/ghc- builder/work/builder/tempbuild/build/inplace/bin/ghc-pkg" --disable- library-for-ghci --enable-library-vanilla --enable-library-profiling --enable-shared --with-hscolour="/usr/local/bin/HsColour" --configure- option=CFLAGS="-Wall -fno-stack-protector -Werror=unused-but-set- variable -Wno-error=inline" --configure-option=LDFLAGS=" " --configure- option=CPPFLAGS=" " --gcc-options="-Wall -fno-stack-protector -Werror =unused-but-set-variable -Wno-error=inline " --configure-option=--with- iconv-includes="/usr/local/include" --configure-option=--with-iconv- libraries="/usr/local/lib" --configure-option=--with-gmp- includes="/usr/local/include" --configure-option=--with-gmp- libraries="/usr/local/lib" --with-gcc="/usr/local/bin/gcc48" --with- ld="/usr/local/bin/ld" --configure-option=--with-cc="/usr/local/bin/gcc48" --with-ar="/usr/local/bin/ar" --with-alex="/usr/local/bin/alex" --with- happy="/usr/local/bin/happy" Configuring unix-2.7.1.0... [...] checking for fdatasync... yes }}} That is the corresponding part of the {{{config.log}}}: {{{ configure:4242: checking for fdatasync configure:4263: /usr/local/bin/gcc48 -c -Wall -fno-stack-protector -Werror=unused-but-set-variable -Wno-error=inline conftest.c >&5 conftest.c: In function 'main': conftest.c:71:1: warning: implicit declaration of function 'fdatasync' [-Wimplicit-function-declaration] fdatasync(4); ^ configure:4263: $? = 0 configure:4271: result: yes }}} Looks like GCC is willing to compile the test code, although it notes that it cannot find the declaration of the {{{fdatasync()}}} function. Unfortunately, the {{{configure}}} script does not instruct GCC to do any linking or be serious on such warnings, so it happily proceeds. For the reference, previously the {{{config.log}}} said something like that instead: {{{ configure:4230: checking for fdatasync configure:4230: /usr/local/bin/gcc48 -o conftest -Wall -fno-stack- protector -Werror=unused-but-set-variable -Wno-error=inline conftest.c >&5 /tmp//ccDCjZtO.o: In function `main': conftest.c:(.text+0xa): undefined reference to `fdatasync' collect2: error: ld returned 1 exit status configure:4230: $? = 1 [...] }}} I am inclined to think that this is caused by the commit [https://github.com/haskell/unix/commit/b06446edd4753f964a46d27ddae864fad97a… b06446edd4753f964a46d27ddae864fad97adc13] for the {{{unix}}} package. Perhaps the following change can fix that, at least it fixed for me: {{{ --- a/mk/warnings.mk +++ b/mk/warnings.mk @@ -16,6 +16,7 @@ SRC_CC_WARNING_OPTS += -Werror=unused-but-set-variable endif # gcc 4.6 gives 3 warning for giveCapabilityToTask not being inlined SRC_CC_WARNING_OPTS += -Wno-error=inline +SRC_CC_WARNING_OPTS += -Werror=implicit-function-declaration endif else }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11137> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9739: GHC 7.8 chokes on recursive classes
by GHC 23 Dec '15

23 Dec '15

#9739: GHC 7.8 chokes on recursive classes -------------------------------------+------------------------------------- Reporter: bitonic | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.8.3 checker) | Operating System: Keywords: | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Type checking this makes GHC 7.8.3 loop: {{{#!hs {-# LANGUAGE MultiParamTypeClasses #-} module Foo where class Class3 a => Class1 a where class Class2 t a where class2 :: (Class3 t) => a -> m class (Class1 t, Class2 t t) => Class3 t where }}} Does not happen in 7.6.3. I think it's something to do with the `Class3` constraint appearing in `class2`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9739> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10426: matchGroupArity panic with PatternSynonyms
by GHC 23 Dec '15

23 Dec '15

#10426: matchGroupArity panic with PatternSynonyms ---------------------------------------+--------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | ---------------------------------------+--------------------------------- {{{#!hs {-# LANGUAGE PatternSynonyms, ViewPatterns, EmptyCase #-} pattern Id <- (id -> _) where }}} which gives: {{{#!hs % ghc -ignore-dot-ghci tmp.FbbzjZ48OO.hs [1 of 1] Compiling Main ( tmp.FbbzjZ48OO.hs, tmp.FbbzjZ48OO.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.10.0.20150316 for i386-unknown-linux): matchGroupArity Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10426> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11098: TH mishandles type variables that begin with an underscore
by GHC 22 Dec '15

22 Dec '15

#11098: TH mishandles type variables that begin with an underscore -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Template | Version: 7.10.2 Haskell | 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 following GHCi exchange was reported [https://github.com/goldfirere /th-desugar/pull/36 here] (you need not follow the link to understand this ticket, though). {{{ Prelude Language.Haskell.TH> runQ [d|foo :: forall _a . _a -> _a;foo x = x|] [SigD foo_6 (ForallT [PlainTV _a_5] [] (AppT (AppT ArrowT (WildCardT (Just _a_5))) (WildCardT (Just _a_5)))),FunD foo_6 [Clause [VarP x_7] (NormalB (VarE x_7)) []]] }}} The problem is that the quoted expression uses no wildcards, yet the TH output does. That quoted expression just uses a type variable that begins with an underscore. Such an expression was allowed in Haskell long before wildcards. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11098> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10982: Warn about unused pattern variables in type families
by GHC 22 Dec '15

22 Dec '15

#10982: Warn about unused pattern variables in type families -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: newcomer | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Now that we have wildcards in type families (#3699) I want to be warned about unused pattern variables in the same way I am warned about them at the term level. For example this should cause a warning that `b` is not used: {{{#!hs type family F a b type instance F a b = a }}} Prefixing unused variable with an underscore should suppress the warning: {{{#!hs type family F a b type instance F a _b = a }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10982> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10967: Release a new stm package on Hackage
by GHC 22 Dec '15

22 Dec '15

#10967: Release a new stm package on Hackage -------------------------------------+------------------------------------- Reporter: svenpanne | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries | Version: (other) | Keywords: stm | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently, the latest stm package on Hackage (2.4.4) doesn't compile with GHC HEAD (see e.g. https://travis-ci.org/haskell- opengl/OpenGL/jobs/85320391), which makes testing of various other packages with HEAD imposiible. Things seem to be fixed in git already, can we have a new release of stm? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10967> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11147: Linker errors related to response files change
by GHC 21 Dec '15

21 Dec '15

#11147: Linker errors related to response files change -------------------------------------+------------------------------------- Reporter: waern | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Build System | Version: 7.11 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: Building GHC | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Hi, Building GHC HEAD in Nix on Linux currently fails with linker errors. See https://github.com/NixOS/nixpkgs/issues/10752 The problem goes away if one reverts GHC commit 296bc70b5ff6c853f2782e9ec5aa47a52110345e. I don't know what the issue is, and I can't be 100% sure it's really a GHC problem and not a Nix one, but I thought it best to record this here. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11147> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10828: TH can't represent all GADTs in its AST
by GHC 21 Dec '15

21 Dec '15

#10828: TH can't represent all GADTs in its AST -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Template | Version: 7.10.2 Haskell | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- For example, it's impossible to add a kind signature on a data type with `DataD`. In {{{Con}}} I believe it's possible to encode GADT constructor signatures using {{{NormalC}}} (haven't tried this yet), but ideally there would be another constructor specific to GADTs to go along with {{{RecC}}}, {{{InfixC}}}, and {{{ForallC}}}. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10828> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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