May 2017 - ghc-tickets

[GHC] #10954: Add class/context information to typed hole relevant bindings
by GHC 02 Apr '18

02 Apr '18

#10954: Add class/context information to typed hole relevant bindings -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #9479 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC's typed hole messages don't currently include any known context information for relevant bindings. For example: {{{#!hs bar :: a ~ b => a -> b -> Int bar x y = _ }}} gets me {{{ Found hole ‘_’ with type: Int Relevant bindings include y :: b (bound at <interactive>:8:42) x :: a (bound at <interactive>:8:40) bar :: a -> b -> Int (bound at <interactive>:8:36) In the expression: _ In an equation for ‘bar’: bar x y = _ }}} The types `a` and `b` are not unified, and the `a ~ b` constraint is not shown. {{{#!hs foo :: Show a => a -> Int foo x = _ }}} gets me {{{ Found hole ‘_’ with type: Int Relevant bindings include x :: a (bound at <interactive>:4:36) foo :: a -> Int (bound at <interactive>:4:32) In the expression: _ In an equation for ‘foo’: foo x = _ }}} The `Show` constraint is lost. === What I want === I'd like context information for all type variables in known bindings, so I can see all the pieces available to help me fill in the hole. === Related ticket === In #9479, Dominique Devriese wants to see any constraints ''on'' an ambiguously-typed hole. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10954> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10267: Add support for typed holes in Template Haskell
by GHC 02 Apr '18

02 Apr '18

#10267: Add support for typed holes in Template Haskell -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1 Component: Template | Operating System: Unknown/Multiple Haskell | Type of failure: None/Unknown Keywords: | Blocked By: Architecture: | Related Tickets: Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I want to be able to work with typed holes using Template Haskell. These are currently rejected: {{{#!hs [d| i :: a -> a i x = _ |] }}} {{{ Expression form not (yet) handled by Template Haskell _ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10267> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10822: GHC inconsistently handles \\?\ for long paths on Windows
by GHC 31 Mar '18

31 Mar '18

#10822: GHC inconsistently handles \\?\ for long paths on Windows -------------------------------------+------------------------------------- Reporter: snoyberg | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Windows Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- To demonstrate what I mean first: {{{ >ghc-pkg init \\?\c:\Users\michael\Desktop\some-pkg-db >dir \\?\c:\Users\Michael\Desktop\some-pkg-db Volume in drive \\?\c: is Windows8_OS Volume Serial Number is CEF7-874D Directory of \\?\c:\Users\Michael\Desktop\some-pkg-db 09/01/2015 09:38 AM <DIR> . 09/01/2015 09:38 AM <DIR> .. 09/01/2015 09:38 AM 40 package.cache 1 File(s) 40 bytes 2 Dir(s) 5,907,509,248 bytes free >ghc -package-db \\?\c:\Users\Michael\Desktop\some-pkg-db ghc: can't find a package database at \\?\c:\Users\Michael\Desktop\some- pkg-db }}} The problem: on Windows by default, paths are limited to 260 characters, which can become a real problem in practice when dealing with the standard library path hierarchy the Cabal library uses and any package with a decent name length. This was a real problem in practice, see: https://github.com/haskell/cabal/issues/2502 Windows has a workaround for this: you can prefix an absolute path with \\?\, see: https://msdn.microsoft.com/en- us/library/windows/desktop/aa365247%28v=vs.85%29.aspx#maxpath It would be very useful if such paths worked with GHC, but currently they do not. I don't yet know how deep the problem is. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10822> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12442: Pure unifier usually doesn't need to unify kinds
by GHC 30 Mar '18

30 Mar '18

#12442: Pure unifier usually doesn't need to unify kinds -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | 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 pure unifier (in `types/Unify.hs`) is used to match up instances with actual types. Since GHC 8, it matches up the kinds with the types in a separate pass. But this is often wasteful, and sometimes downright wrong. It's wasteful because most invocations of the unifier on a list of types pass in well-kinded arguments to some type constructor. Because the kinds of type constructors are closed, if we process the list left-to-right, we will always unify the kinds of later arguments before we get to them. So we shouldn't take another pass on the kinds. It's wrong because it's conceivable for the kind to include a type family application, and using a type family application as a template in the pure unifier is very silly, indeed. I cam across this while trying to translate Idris's algebraic effects library to Haskell. My reduced test case is attached. Patch on the way. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12442> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12176: Failure of bidirectional type inference at the kind level
by GHC 30 Mar '18

30 Mar '18

#12176: Failure of bidirectional type inference at the kind level -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: TypeInType | 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 feeling particularly sadistic towards GHC at the moment, and so I fed it this: {{{ import Data.Kind data Proxy :: forall k. k -> Type where MkProxy :: forall k (a :: k). Proxy a data X where MkX :: forall (k :: Type) (a :: k). Proxy a -> X type Expr = (MkX :: forall (a :: Bool). Proxy a -> X) type family Foo (x :: forall (a :: k). Proxy a -> X) where Foo (MkX :: forall (a :: k). Proxy a -> X) = (MkProxy :: Proxy k) }}} Incredibly, GHC accepts it! And it even means what I wish it to, with GHCi telling me the following (with `-fprint-explicit-kinds`): {{{ λ> :i Foo type family Foo k (x :: forall (a :: k). Proxy k a -> X) :: Proxy * k where [k] Foo k ('MkX k) = 'MkProxy * k }}} That is, I wished to extract the kind parameter to `MkK`, matching against a partially-applied `MkX`, and GHC understood that intention. However, sadly, writing `Foo Expr` produces {{{ • Expected kind ‘forall (a :: k0). Proxy k0 a -> X’, but ‘Expr a0’ has kind ‘Proxy Bool a0 -> X’ • In the first argument of ‘Foo’, namely ‘Expr’ In the type ‘Foo Expr’ In the type family declaration for ‘XXX’ }}} For some reason, `Expr` is getting instantiated when it shouldn't be. Perhaps there's a simpler test case demonstrating the bug, but I feel so gleeful that this chicanery is accepted at all that I wanted to post. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12176> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9406: unexpected failure for T7837(profasm)
by GHC 29 Mar '18

29 Mar '18

#9406: unexpected failure for T7837(profasm) -------------------------------------+------------------------------------- Reporter: jrp | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Test Suite | Version: 7.8.3 Keywords: T7837 | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: Incorrect Difficulty: Unknown | result at runtime Blocked By: | Test Case: T7837 Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- This may be a test suite configuration error as the normal case works. When run with an llvm-perf build of the HEAD, I get: {{{ =====> T7837(normal) 1395 of 4068 [0, 0, 0] cd ./indexed-types/should_compile && '/Users/jrp/Projects/haskell/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7837.hs -O -ddump-rule-firings >T7837.comp.stderr 2>&1 =====> T7837(profasm) 1395 of 4068 [0, 0, 0] cd ./indexed-types/should_compile && '/Users/jrp/Projects/haskell/ghc/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7837.hs -O -prof -static -auto-all -O -ddump-rule- firings >T7837.comp.stderr 2>&1 Actual stderr output differs from expected: --- ./indexed-types/should_compile/T7837.stderr 2014-08-03 11:36:53.000000000 +0100 +++ ./indexed-types/should_compile/T7837.comp.stderr 2014-08-04 23:16:34.000000000 +0100 @@ -1,3 +1,4 @@ Rule fired: Class op abs Rule fired: Class op signum Rule fired: normalize/Double +Rule fired: Class op / *** unexpected failure for T7837(profasm) Unexpected results from: TEST="T7837" OVERALL SUMMARY for test run started at Mon Aug 4 23:16:32 2014 BST 0:00:02 spent to go through 4068 total tests, which gave rise to 19536 test cases, of which 19534 were skipped 0 had missing libraries 1 expected passes 0 expected failures 0 caused framework failures 0 unexpected passes 1 unexpected failures Unexpected failures: indexed-types/should_compile T7837 [stderr mismatch] (profasm) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9406> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13062: `opt' failed in phase `LLVM Optimiser'. (Exit code: -11)
by GHC 29 Mar '18

29 Mar '18

#13062: `opt' failed in phase `LLVM Optimiser'. (Exit code: -11) -------------------------------------+------------------------------------- Reporter: 2bdkid | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (LLVM) | Keywords: LLVM | Operating System: Linux Optimiser -11 | Architecture: arm | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While building [https://hackage.haskell.org/package/unicode-transforms] it fails with: {{{ cabal: Entering directory '/tmp/cabal-tmp-7667/unicode-transforms-0.2.0' Configuring unicode-transforms-0.2.0... Building unicode-transforms-0.2.0... Preprocessing library unicode-transforms-0.2.0... [ 1 of 12] Compiling Data.Unicode.Properties.DecompositionsK ( Data/Unicode/Properties/DecompositionsK.hs, dist/build/Data/Unicode/Properties/DecompositionsK.o ) [ 2 of 12] Compiling Data.Unicode.Properties.Decompositions ( Data/Unicode/Properties/Decompositions.hs, dist/build/Data/Unicode/Properties/Decompositions.o ) [ 3 of 12] Compiling Data.Unicode.Properties.DecomposableK ( Data/Unicode/Properties/DecomposableK.hs, dist/build/Data/Unicode/Properties/DecomposableK.o ) `opt' failed in phase `LLVM Optimiser'. (Exit code: -11) cabal: Leaving directory '/tmp/cabal-tmp-7667/unicode-transforms-0.2.0' }}} Other details: {{{ $ ghc --version The Glorious Glasgow Haskell Compilation System, version 8.0.1 $ opt --version LLVM (http://llvm.org/) LLVM version 3.7.1 Optimized build. Default target: armv7l-unknown-linux-gnueabihf Host CPU: (unknown) }}} I already submitted an issue to the package's bug tracker, but it is believed to be a GHC bug: [https://github.com/harendra-kumar/unicode- transforms/issues/10] -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13062> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12915: cmmImplementSwitchPlans creates duplicate blocks
by GHC 27 Mar '18

27 Mar '18

#12915: cmmImplementSwitchPlans creates duplicate blocks -------------------------------------+------------------------------------- Reporter: alexbiehl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- Given this c-- code *after* common block elimination and *before* cmmImplementSwitchPlans: {{{#!hs ... cfzc: _sfh3::P64 = R1; _cfB7::I64 = %MO_UU_Conv_W32_W64(I32[I64[_sfh3::P64 - 1] - 4]); switch [0 .. 20] _cfB7::I64 { case 2 : goto cfAR; case 4 : goto cfAV; case 6 : goto cfAZ; default: goto cfAC; } cfAZ: _sfh6::I64 = I64[_sfh3::P64 + 7]; _sfgp::I64 = 1; goto sfgo; cfAV: _sfh5::I64 = I64[_sfh3::P64 + 7]; _sfgp::I64 = 1; goto sfgo; cfAR: _sfh4::I64 = I64[_sfh3::P64 + 7]; _sfgp::I64 = 1; goto sfgo; sfgo: ... }}} Everything is fine, the blocks cfAZ, cfAV and cfAR are all a little different. But after cmmImplementSwitchPlans the code becomes: {{{#!hs ... cfzc: _sfgl::I64 = I64[Sp + 24]; _sfgn::P64 = P64[Sp + 16]; _cfB7::I64 = %MO_UU_Conv_W32_W64(I32[I64[R1 - 1] - 4]); if (_cfB7::I64 < 5) goto ufBe; else goto ufBg; ufBe: if (_cfB7::I64 < 4) goto ufBf; else goto cfAV; ufBf: if (_cfB7::I64 != 2) goto cfAC; else goto cfAR; cfAR: _sfgp::I64 = 1; goto sfgo; cfAV: _sfgp::I64 = 1; goto sfgo; ufBg: if (_cfB7::I64 != 6) goto cfAC; else goto cfAZ; cfAZ: _sfgp::I64 = 1; goto sfgo; sfgo: ... }}} We can now see that cfAZ, cfAV and cfAR are code duplicates! Now, https://github.com/ghc/ghc/blob/master/compiler/cmm/CmmPipeline.hs#L72 states {{{ ... ----------- Eliminate common blocks ------------------------------------- g <- {-# SCC "elimCommonBlocks" #-} condPass Opt_CmmElimCommonBlocks elimCommonBlocks g Opt_D_dump_cmm_cbe "Post common block elimination" -- Any work storing block Labels must be performed _after_ -- elimCommonBlocks g <- {-# SCC "createSwitchPlans" #-} runUniqSM $ cmmImplementSwitchPlans dflags g dump Opt_D_dump_cmm_switch "Post switch plan" g ... }}} For some reason I don't understand cmmImplementSwitchPlans is run *after* elimCommonBlocks. Although it seems elimCommonBlocks can deal with the constructs introduced in cmmImplementSwitchPlans. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12915> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13643: Core lint error with TypeInType and TypeFamilyDependencies
by GHC 26 Mar '18

26 Mar '18

#13643: Core lint error with TypeInType and TypeFamilyDependencies -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple InjectiveFamilies, TypeInType | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: 12102 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In the code {{{#!hs {-# Language TypeFamilyDependencies #-} {-# Language RankNTypes #-} {-# Language KindSignatures #-} {-# Language DataKinds #-} {-# Language TypeInType #-} {-# Language GADTs #-} import Data.Kind (Type) data Code = I type family Interp (a :: Code) = (res :: Type) | res -> a where Interp I = Bool data T :: forall a. Interp a -> Type where MkNat :: T False instance Show (T a) where show _ = "MkNat" main = do print MkNat }}} but add `{-# Options_GHC -dcore-lint #-}` and we get the attached log from running `runghc /tmp/tPb2.hs > /tmp/tPb2.log`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13643> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10536: Clear up how to turn off dynamic linking in build.mk
by GHC 26 Mar '18

26 Mar '18

#10536: Clear up how to turn off dynamic linking in build.mk -------------------------------------+------------------------------------- Reporter: thomie | Owner: Type: task | Status: new Priority: normal | Milestone: 7.12.1 Component: Build | Version: 7.10.1 System | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- See https://mail.haskell.org/pipermail/ghc-devs/2014-December/007725.html -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10536> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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