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[GHC] #13268: Backpack doesn't work with Template Haskell, even when it should
by GHC 10 Sep '17

10 Sep '17

#13268: Backpack doesn't work with Template Haskell, even when it should -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.0.1 Haskell | Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Obviously, we can't run Template Haskell from an indefinite package when we are (solely) typechecking the indefinite package itself. But in principle, Template Haskell code from other packages should be fair game. Alas, this not the case, because GHC attempts to dynamic link in libraries for ALL dependencies, including the ones we don't have code for. Quick fix should be to not link those in? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13268> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14210: bkp files cannot find TemplateHaskell symbols (even without Backpack features)
by GHC 10 Sep '17

10 Sep '17

#14210: bkp files cannot find TemplateHaskell symbols (even without Backpack features) -------------------------------------+------------------------------------- Reporter: ezyang | Owner: (none) Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 8.2.1 (Linking) | Keywords: backpack | 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 TemplateHaskell #-} unit th where module TH where f = [d| x = True |] unit p where dependency th module B where import TH $(f) }}} When run, this gives: {{{ ghc: ^^ Could not load 'th_TH_f_closure', dependency unresolved. See top entry above. ByteCodeLink.lookupCE During interactive linking, GHCi couldn't find the following symbol: th_TH_f_closure This may be due to you not asking GHCi to load extra object files, archives or DLLs needed by your current session. Restart GHCi, specifying the missing library using the -L/path/to/object/dir and -lmissinglibname flags, or simply by naming the relevant files on the GHCi command line. Alternatively, this link failure might indicate a bug in GHCi. If you suspect the latter, please send a bug report to: glasgow-haskell-bugs(a)haskell.org }}} I am not sure how easy or hard the fix is. We should bump this priority up if we get more serious about supporting Template Haskell with Backpack. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14210> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14207: Levity polymorphic GADT requires extra type signatures
by GHC 09 Sep '17

09 Sep '17

#14207: Levity polymorphic GADT requires extra type signatures -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple LevityPolymorphism | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This does not compile: {{{#!hs data Foo s (a :: TYPE k) where FooC :: Foo s Int# }}} However, this does: {{{#!hs data Foo (s :: Type) (a :: TYPE k) where FooC :: Foo s Int# }}} This also works: {{{#!hs data Foo (s :: j) (a :: TYPE k) where FooC :: Foo s Int# }}} These are all of the language pragmas I have enabled: {{{#!hs {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE RankNTypes #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE BangPatterns #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE TypeInType #-} {-# LANGUAGE PolyKinds #-} {-# LANGUAGE KindSignatures #-} {-# LANGUAGE UnboxedSums #-} {-# LANGUAGE UnboxedTuples #-} {-# LANGUAGE MagicHash #-} {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE UndecidableInstances #-} }}} This is pretty easy to work around, but I think it's an incorrect behavior. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14207> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14205: GHCI freaked out when I tryed to load a program and told me to report it as a bug.
by GHC 09 Sep '17

09 Sep '17

#14205: GHCI freaked out when I tryed to load a program and told me to report it as a bug. -------------------------------------+------------------------------------- Reporter: Ebanflo | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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: -------------------------------------+------------------------------------- ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): initTc: unsolved constraints WC {wc_insol = [W] %_a2g7 :: t_a2g6[tau:1] (CHoleCan: %)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug > -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14205> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #6132: Can't use both shebang line and #ifdef declarations in the same file.
by GHC 09 Sep '17

09 Sep '17

#6132: Can't use both shebang line and #ifdef declarations in the same file. -------------------------------------+------------------------------------- Reporter: gfxmonk | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 7.0.4 (Parser) | Resolution: | Keywords: cpp Operating System: MacOS X | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: runghc/T6132 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by lelf): * cc: lelf (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/6132#comment:18> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14090: Static pointers are not being registered under certain conditions
by GHC 09 Sep '17

09 Sep '17

#14090: Static pointers are not being registered under certain conditions -------------------------------------+------------------------------------- Reporter: mnislaih | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- It seems that if the module is compiled with -O2 only the static pointers in the module export list survive the Simplifier. This is a regression. {{{ {-# LANGUAGE StaticPointers #-} import GHC.StaticPtr staticHello :: StaticPtr String staticHello = static "hello" main = do keys <- staticPtrKeys if null keys then error "static ptrs are not being registered" else putStrLn "Everything is fine" }}} {{{ pepe:~/scratch$ stack --resolver ghc-8.2.1 script --optimize bug-spt.hs Using resolver: ghc-8.2.1 specified on command line bug-spt: static ptrs are not being registered CallStack (from HasCallStack): error, called at bug-spt.hs:11:10 in main:Main pepe:~/scratch$ stack --resolver ghc-8.0.2 script --optimize bug-spt.hs Using resolver: ghc-8.0.2 specified on command line Everything is fine }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14090> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9661: Branchless ==# is compiled to branchy code
by GHC 08 Sep '17

08 Sep '17

#9661: Branchless ==# is compiled to branchy code -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Runtime Blocked By: | performance bug Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- This started as a comment on #6135, but Jan Stolarek requested that I file a separate report. The branchless tests `<#`, `>#`, `<=#`, and `>=#`, and their wordy cousins, seem to work properly, but `==#` and `eqWord#` don't. If I write {{{#!hs foo x = tagToEnum# ((x <# 3#) `orI#` (x ># 100#) `orI#` (x ==# 12#) `orI#` (x ==# 15#)) }}} I get (in 7.8.3 and in 7.9) {{{#!hs IsDigit.foo :: GHC.Prim.Int# -> GHC.Types.Bool [GblId, Arity=1, Caf=NoCafRefs, Str=DmdType <S,1*U>, Unf=Unf{Src=InlineStable, TopLvl=True, Value=True, ConLike=True, WorkFree=True, Expandable=True, Guidance=ALWAYS_IF(arity=1,unsat_ok=True,boring_ok=False) Tmpl= \ (x3_a2if [Occ=Once!] :: GHC.Prim.Int#) -> case x3_a2if of wild_Xe { __DEFAULT -> GHC.Prim.tagToEnum# @ GHC.Types.Bool (GHC.Prim.orI# (GHC.Prim.<# wild_Xe 3) (GHC.Prim.># wild_Xe 100)); 12 -> GHC.Types.True; 15 -> GHC.Types.True }}] IsDigit.foo = \ (x3_a2if :: GHC.Prim.Int#) -> case x3_a2if of wild_Xe { __DEFAULT -> GHC.Prim.tagToEnum# @ GHC.Types.Bool (GHC.Prim.orI# (GHC.Prim.<# wild_Xe 3) (GHC.Prim.># wild_Xe 100)); 12 -> GHC.Types.True; 15 -> GHC.Types.True }}} and branching assembly to match. Jan Stolarek indicates this is probably a problem with constant folding. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9661> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14195: Generalize makeStableName#
by GHC 08 Sep '17

08 Sep '17

#14195: Generalize makeStableName# -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 8.2.1 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 function `makeStableName#` has the following type: {{{ makeStableName# :: a -> State# RealWorld -> (#State# RealWorld, StableName# a#) }}} I believe that it could safely be changed to: {{{ makeStableName# :: a -> State# s -> (#State# s, StableName# a#) }}} Currently, I have some code that looks like this: {{{ {-# LANGUAGE MagicHash #-} {-# LANGUAGE UnboxedTuples #-} module Example ( Stable , stabilize , destabilize ) where import GHC.Prim import GHC.ST data Stable s a = Stable (StableName# a) a stabilize :: a -> ST s (Stable s a) stabilize a = ST $ \ s -> case makeStableName# a (unsafeCoerce# s) of (# s', sn #) -> (# unsafeCoerce# s', Stable sn a #) destabilize :: Stable s a -> a destabilize (Stable _ a) = a instance Eq a => Eq (Stable s a) where Stable sn1 a1 == Stable sn2 a2 = case eqStableName# sn1 sn2 of 0# -> a1 == a2 _ -> True }}} I want to be working in `ST`, not in `IO`, and I believe that this use of `unsafeCoerce#` is safe. However, it would be nice to not have to use it at all. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14195> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14194: ghci 8.0.2 panics
by GHC 07 Sep '17

07 Sep '17

#14194: ghci 8.0.2 panics -------------------------------------+------------------------------------- Reporter: jakubdaniel | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 | Type of failure: None/Unknown (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I know it is rather hard to replicate but (I currently cannot check whether it still occurs in 8.0.2+): git clone https://github.com/jakubdaniel/expressions git clone https://github.com/jakubdaniel/expressions-z3 hg clone https://bitbucket.org/jd823592/z3-haskell cd expressions-z3 cabal sandbox init cabal sandbox add-source ../expression cabal sandbox add-source ../z3-haskell cabal install && cabal exec ghci λ> -- forget to :set -XTypeInType λ> :m Z3.Monad Data.Expression λ> -- forget to :m Data.Expression.Z3 λ> evalZ3 $ astToString =<< toZ3 (forall [var "x" :: Var 'IntegralSort] (exists [var "y" :: Var 'IntegralSort] (var "x" .+. var "y" .=. cnst 0)) :: Lia 'BooleanSort) ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): initTc: unsolved constraints WC {wc_insol = [W] toZ3_a4CL :: t_a4CK[tau:1] (CHoleCan: toZ3) [W] toZ3_a4Dx :: t_a4Dw[tau:1] (CHoleCan: toZ3)} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14194> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10365: Make Semigroup as a superclass of Monoid
by GHC 07 Sep '17

07 Sep '17

#10365: Make Semigroup as a superclass of Monoid -------------------------------------+------------------------------------- Reporter: gidyn | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1 Component: | Operating System: Unknown/Multiple libraries/base | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- See http://haskell.1045720.n5.nabble.com/Proposal-Make-Semigroup-as-a -superclass-of-Monoid-td5767835.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10365> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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