April 2016 - ghc-tickets

[GHC] #11433: sphinx: Error: source directory and destination directory are same.
by GHC 08 Sep '16

08 Sep '16

#11433: sphinx: Error: source directory and destination directory are same. -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.0.1-rc1 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: -------------------------------------+------------------------------------- When building the Debian package, the build fails with {{{ writing output... [100%] win32-dlls generating indices... genindex writing additional pages... search copying images... [100%] images/prof_scc.svg copying static files... done copying extra files... done dumping search index in English (code: en) ... done dumping object inventory... done build succeeded, 5 warnings. /usr/bin/sphinx-build -b man -d docs/users_guide/.doctrees-man docs/users_guide docs/users_guide Error: source directory and destination directory are same. docs/users_guide/ghc.mk:30: recipe for target 'docs/users_guide/ghc.1' failed make[3]: *** [docs/users_guide/ghc.1] Error 1 Makefile:122: recipe for target 'all' failed make[2]: *** [all] Error 2 make[2]: Leaving directory '/<<PKGBUILDDIR>>' }}} Full build log attached. Any idea what might be causing this? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11433> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9880: ghc crashes on th splices in instance context
by GHC 08 Sep '16

08 Sep '16

#9880: ghc crashes on th splices in instance context -------------------------------------+------------------------------------- Reporter: Philonous | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Given Class.hs: {{{#!hs module Class where class Foo a where bar :: a -> Int }}} TH.hs {{{#!hs {-# LANGUAGE TemplateHaskell #-} module TH where import Class import Language.Haskell.TH mkFun :: Q [Dec] mkFun = return [FunD 'bar [Clause [WildP] (NormalB (LitE (IntegerL 0))) []]] }}} and Instance.hs {{{#!hs {-# LANGUAGE TemplateHaskell #-} module Instance where import TH import Class instance Foo Bool where $(mkFun) }}} compiling the project crashes ghc with {{{ #ghc --make Instance.hs [2 of 3] Compiling TH ( TH.hs, TH.o ) [3 of 3] Compiling Instance ( Instance.hs, Instance.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-unknown-linux): cvBindsAndSigs $[splice{v}]mkFun{v} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9880> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10062: Codegen on sequential FFI calls is not very good
by GHC 06 Sep '16

06 Sep '16

#10062: Codegen on sequential FFI calls is not very good -------------------------------------+------------------------------------- Reporter: chadaustin | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 (CodeGen) | Operating System: Unknown/Multiple Keywords: | Type of failure: Runtime Architecture: | performance bug Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I'm writing a library for efficiently building up a byte buffer. The fastest approach I've found is via FFI, with restricted effects like ST. It's over twice as fast as ByteString Builder. Consider this example API usage: https://github.com/chadaustin/buffer- builder/blob/6bd0a39c56f63ab751faf29f9784ac87d52638be/bench/Bench.hs#L46 It compiles into an instruction sequence containing direct, sequenced FFI calls. For example, the last three calls work out to: addq $8,%rsp movq %rbx,%rdi movq 72(%rsp),%rax movq %rax,%rsi subq $8,%rsp movl $0,%eax call bw_append_bsz addq $8,%rsp movq %rbx,%rdi movl $35,%esi subq $8,%rsp movl $0,%eax call bw_append_byte addq $8,%rsp movq %rbx,%rdi movq 64(%rsp),%rax movq %rax,%rsi subq $8,%rsp movl $0,%eax call bw_append_bsz I don't know why rsp is being changed so much. I also can't explain the assignment to eax before the call. (It should also be xorl eax,eax, I would think.) To my reading, the above instruction sequence could be reduced to: movq %rbx,%rdi movq 64(%rsp),%rsi call bw_append_bsz movq %rbx,%rdi movl $35,%esi call bw_append_byte movq %rbx,%rdi movq 56(%rsp),%rsi call bw_append_bsz To reproduce, check out git@github.com:chadaustin/buffer-builder.git at revision 6bd0a39c56f63ab751faf29f9784ac87d52638be cabal configure --enable-benchmarks cabal bench And then look at the ./dist/build/bench/bench-tmp/bench/Bench.dump-asm file. This is specifically on OS X 64-bit with GHC 7.8.3, but I saw similar code generation on GHC 7.6 on Linux 64-bit. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10062> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11981: unknown symbol `__udivti3' when BuildFlavour = perf-llvm
by GHC 06 Sep '16

06 Sep '16

#11981: unknown symbol `__udivti3' when BuildFlavour = perf-llvm -------------------------------------+------------------------------------- Reporter: erikd | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Building git HEAD with `BuildFlavour = perf-llvm` and then running the tests results in 500+ tests failing, all with the same error: {{{ ghc-stage2: /xxx/libraries/ghc-prim/dist-install/build/HSghc- prim-0.5.0.0.o: unknown symbol `__udivti3' ghc-stage2: unable to load package `ghc-prim-0.5.0.0' }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11981> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10858: Smaller generated instances
by GHC 06 Sep '16

06 Sep '16

#10858: Smaller generated instances -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- With very large modules with lots of deriving code, GHC spends quite some time compiling. I believe that we can improve things by reducing the size of the generated code. (More in the comments) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10858> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10161: GHC does not relink if a library's code changed
by GHC 03 Sep '16

03 Sep '16

#10161: GHC does not relink if a library's code changed -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Test case for reproducing: https://github.com/nh2/ghc-relinking-avoidance- bug/ ---- {{{myexe}}} is an executable that depends on {{{mylib}}}, whose {{{myfun = putStrLn "output 1"}}}. If we install {{{mylib}}}, compile {{{myexe}}}, then change mylib's code to {{{myfun = putStrLn "output 2"}}}, re-install it, and then compile {{{myexe}}}, then GHC does not notice that the library code changed. It avoids re-linking myexe, with the result that the program prints {{{output 1}}} when you told it to compile against code that prints {{{output 2}}}. ---- Note that I had to use {{{NOINLINE myfun}}} to trigger the bug, since otherwise {{{myfun}}}'s code would have ended up in the interface file, thus changing the package ID, which naturally forces GHC to relink (even re-compile). With the {{{NOINLINE}}}, the package IDs of the two different versions of {{{myfun}}} are completely identical. I think that is correct, since the package ID only hashes the API and ABI, not the actual implementation, right? How does GHC decide when to relink? I think in the present case, it doesn't notice that the object/archive file of the library changed. Does it check that somehow? Just looking at API and API can't be enough to make a decision for linking. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10161> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11565: Restore code to handle '-fmax-worker-args' flag
by GHC 03 Sep '16

03 Sep '16

#11565: Restore code to handle '-fmax-worker-args' flag -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | 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: -------------------------------------+------------------------------------- When i had a pass through DynFlags I've noticed dead code: https://phabricator.haskell.org/D1727 It was accidentally lost 3 years ago in major update changeset:0831a12ea2fc73c33652eeec1adc79fa19700578 The consensus is to try to put option handling back. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11565> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10923: GHC should recompile if flags change
by GHC 03 Sep '16

03 Sep '16

#10923: GHC should recompile if flags change -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | -------------------------------------+------------------------------------- Example: {{{ ezyang@sabre:~$ rm B.hi ezyang@sabre:~$ Dev/ghc-7.10.2/usr/bin/ghc -c B.hs ezyang@sabre:~$ Dev/ghc-7.10.2/usr/bin/ghc -c B.hs -O compilation IS NOT required }}} Pretty minor, but would be nice to have fixed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10923> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11740: RFC kind synonyms
by GHC 03 Sep '16

03 Sep '16

#11740: RFC kind synonyms -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | 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: -------------------------------------+------------------------------------- Are any of these useful now that we have kind synonyms: {{{#!hs -- Control.Category type Cat k = k -> k -> Type -- Data.Kind type Kind = Type type Types = [Type] type TypeClass = Type -> Constraint }}} `Cat` is not limited to `Control.Category` but applies in all [https://github.com/ekmett/hask/blob/master/src/Hask/Category.hs#L68 hask], [https://github.com/mikeizbicki/subhask/blob/b5433b959914d8214bcc4f130ff1b3d… subhask] and is defined by [https://github.com/ttuegel/recategorize/blob/master/src/Category/Category.h… recategorize]. It lets you rewrite: {{{#!hs -- newtype Yoneda (p :: i -> i -> *) (a :: i) (b :: i) = Op { getOp :: p b a } newtype Yoneda :: Cat i -> Cat i where Op :: { getOp :: p b a } -> Yoneda p a b -- type family Op (p :: i -> i -> *) :: i -> i -> * where type family Op (p :: Cat i) :: Cat i where Op (Yoneda p) = p Op p = Yoneda p -- data CatT (cat :: * -> * -> *) (a :: k) (b :: k) (cat1 :: k -> k -> *) (cat2 :: k -> k -> *) data CatT (cat :: Cat Type) (a :: k) (b :: k) (cat1 :: Cat k) (cat2 :: Cat k) -- class (Category' (Dom f), Category' (Cod f)) => Functor (f :: i -> j) where -- type Dom f :: i -> i -> * -- type Cod f :: j -> j -> * class (Category' (Dom f), Category' (Cod f)) => Functor (f :: i -> j) where type Dom f :: Cat i type Cod f :: Cat j -- data Nat (p :: i -> i -> *) (q :: j -> j -> *) (f :: i -> j) (g :: i -> j) where data Nat (p :: Cat i) (q :: Cat j) (f :: i -> j) (g :: i -> j) where -- instance Cartesian ((->) :: * -> * -> *) where instance Cartesian ((->) :: Cat Type) where }}} and {{{#!hs -- class (f x, g x) => And (f :: * -> Constraint) (g :: * -> Constraint) (x :: *) -- instance (f x, g x) => And (f :: * -> Constraint) (g :: * -> Constraint) (x :: *) class (f x, g x) => And (f :: TypeClass) (g :: TypeClass) (x :: *) instance (f x, g x) => And (f :: TypeClass) (g :: TypeClass) (x :: *) -- ToContext (fs :: [TypeClass]) :: TypeClass where type family ToContext (fs :: [* -> Constraint]) :: * -> Constraint where ToContext (f:g:fs) = And f (ToContext (g:fs)) ToContext '[f] = f }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11740> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10963: Beginner-targeted language extension
by GHC 30 Aug '16

30 Aug '16

#10963: Beginner-targeted language extension -------------------------------------+------------------------------------- Reporter: kanetw | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 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: -------------------------------------+------------------------------------- FMP significantly complicated type signatures such as `length :: Foldable t => t a -> Int`, which makes teaching Haskell more difficult. I propose a language extension `-XBeginner` which instructs GHC(i) to specialize `Foldable` and `Traversable` to `[]` when possible and in case of an ambiguous instance, default those to `[]`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10963> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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