April 2018 - ghc-tickets

[GHC] #14860: QuantifiedConstraints: Can't quantify constraint involving type family
by GHC 16 Feb '19

16 Feb '19

#14860: QuantifiedConstraints: Can't quantify constraint involving type family -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 (Type checker) | Keywords: | Operating System: Unknown/Multiple QuantifiedConstraints wipT2893 | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This program fails to typecheck using the `wip/T2893` branch, to my surprise: {{{#!hs {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE GADTs #-} {-# LANGUAGE QuantifiedConstraints #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE UndecidableInstances #-} module Bug where import Data.Proxy type family Apply (f :: * -> *) a type instance Apply Proxy a = Proxy a data ExTyFam f where MkExTyFam :: Apply f a -> ExTyFam f instance (forall a. Show (Apply f a)) => Show (ExTyFam f) where show (MkExTyFam x) = show x showsPrec = undefined -- Not defining these leads to the oddities observed in showList = undefined -- https://ghc.haskell.org/trac/ghc/ticket/5927#comment:32 test :: ExTyFam Proxy -> String test = show }}} This fails with: {{{ $ ghc-cq/inplace/bin/ghc-stage2 --interactive Bug.hs GHCi, version 8.5.20180128: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Bug ( Bug.hs, interpreted ) Bug.hs:17:24: error: • Could not deduce (Show (Apply f a)) arising from a use of ‘show’ from the context: forall a. Show (Apply f a) bound by the instance declaration at Bug.hs:16:10-57 • In the expression: show x In an equation for ‘show’: show (MkExTyFam x) = show x In the instance declaration for ‘Show (ExTyFam f)’ | 17 | show (MkExTyFam x) = show x | ^^^^^^ }}} I would have expected the `(forall a. Show (Apply f a))` quantified constraint to kick in, but it didn't. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14860> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11786: Need -fno-print-explicit-runtime-reps to work on IfaceType, else RuntimeRep leaks
by GHC 14 Feb '19

14 Feb '19

#11786: Need -fno-print-explicit-runtime-reps to work on IfaceType, else RuntimeRep leaks -------------------------------------+------------------------------------- Reporter: simonpj | 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: -------------------------------------+------------------------------------- After #11549, we are suppose not to show `RuntimeRep` to users, when `-fno-print-explicit-runtime-reps` is on. But we do: {{{ :info ($) Prelude> :i ($) ($) :: forall (r :: GHC.Types.RuntimeRep) a (b :: TYPE r). (a -> b) -> a -> b -- Defined in ‘GHC.Base’ }}} This happens because the runtime-rep-suppression happens on `Type`, but for `:info` we use `pprInfo` which uses `tyThingToIfaceDecl` and then prints it. And `tyThingToIfaceDecl` doesn't know about the `-fprint- explicit-runtime-reps` flag; and I'd like to keep it that way. We want to change `pprType` to convert to `IfaceType` and then print anyway. I suppose that this means that the pretty-printer for `IfaceType` needs to know about this runtime-rep suppression. That's a bit tiresome, but not impossible, especially since there is no shadowing to worry about. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11786> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10187: Panic: RegAlloc.Liveness.computeLivenss; SCCs aren't in reverse dependent order; bad blockId c8xHd
by GHC 14 Feb '19

14 Feb '19

#10187: Panic: RegAlloc.Liveness.computeLivenss; SCCs aren't in reverse dependent order; bad blockId c8xHd -----------------------------------+--------------------------------------- Reporter: mietek | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: Compile-time crash Test Case: | Blocked By: Blocking: | Related Tickets: #9541, #9031 Differential Revisions: | -----------------------------------+--------------------------------------- I’ve found another instance of the elusive `RegAlloc.Liveness.computeLivenss` bug, by attempting to bootstrap ''cabal-install'' 1.20.0.6 with GHC 7.8.4 on 32-bit CentOS 6, released on 27/05/2013 (available on [https://aws.amazon.com/marketplace/pp/B00A6KZBC6/ Amazon EC2]). Unfortunately, I’m unable to reproduce the bug on a subsequent attempt. Cosmic rays? {{{ Configuring text-1.1.0.1... Building text-1.1.0.1... Preprocessing library text-1.1.0.1... [ 1 of 43] Compiling Data.Text.Internal.Read ( Data/Text/Internal/Read.hs, dist/build/Data/Text/Internal/Read.o ) [ 2 of 43] Compiling Data.Text.Internal.Encoding.Utf32 ( Data/Text/Internal/Encoding/Utf32.hs, dist/build/Data/Text/Internal/Encoding/Utf32.o ) [ 3 of 43] Compiling Data.Text.Internal.Fusion.Size ( Data/Text/Internal/Fusion/Size.hs, dist/build/Data/Text/Internal/Fusion/Size.o ) [ 4 of 43] Compiling Data.Text.Internal.Builder.RealFloat.Functions ( Data/Text/Internal/Builder/RealFloat/Functions.hs, dist/build/Data/Text/Internal/Builder/RealFloat/Functions.o ) [ 5 of 43] Compiling Data.Text.Internal.Builder.Int.Digits ( Data/Text/Internal/Builder/Int/Digits.hs, dist/build/Data/Text/Internal/Builder/Int/Digits.o ) [ 6 of 43] Compiling Data.Text.Internal.Fusion.Types ( Data/Text/Internal/Fusion/Types.hs, dist/build/Data/Text/Internal/Fusion/Types.o ) [ 7 of 43] Compiling Data.Text.Internal.Fusion.CaseMapping ( Data/Text/Internal/Fusion/CaseMapping.hs, dist/build/Data/Text/Internal/Fusion/CaseMapping.o ) [ 8 of 43] Compiling Data.Text.Encoding.Error ( Data/Text/Encoding/Error.hs, dist/build/Data/Text/Encoding/Error.o ) [ 9 of 43] Compiling Data.Text.Internal.Unsafe.Shift ( Data/Text/Internal/Unsafe/Shift.hs, dist/build/Data/Text/Internal/Unsafe/Shift.o ) [10 of 43] Compiling Data.Text.Internal.Encoding.Utf16 ( Data/Text/Internal/Encoding/Utf16.hs, dist/build/Data/Text/Internal/Encoding/Utf16.o ) [11 of 43] Compiling Data.Text.Internal.Functions ( Data/Text/Internal/Functions.hs, dist/build/Data/Text/Internal/Functions.o ) [12 of 43] Compiling Data.Text.Internal.Unsafe ( Data/Text/Internal/Unsafe.hs, dist/build/Data/Text/Internal/Unsafe.o ) [13 of 43] Compiling Data.Text.Internal.Fusion.Common ( Data/Text/Internal/Fusion/Common.hs, dist/build/Data/Text/Internal/Fusion/Common.o ) [14 of 43] Compiling Data.Text.Array ( Data/Text/Array.hs, dist/build/Data/Text/Array.o ) [15 of 43] Compiling Data.Text.Internal.Unsafe.Char ( Data/Text/Internal/Unsafe/Char.hs, dist/build/Data/Text/Internal/Unsafe/Char.o ) [16 of 43] Compiling Data.Text.Internal ( Data/Text/Internal.hs, dist/build/Data/Text/Internal.o ) [17 of 43] Compiling Data.Text.Unsafe ( Data/Text/Unsafe.hs, dist/build/Data/Text/Unsafe.o ) [18 of 43] Compiling Data.Text.Internal.Private ( Data/Text/Internal/Private.hs, dist/build/Data/Text/Internal/Private.o ) [19 of 43] Compiling Data.Text.Internal.Fusion ( Data/Text/Internal/Fusion.hs, dist/build/Data/Text/Internal/Fusion.o ) [20 of 43] Compiling Data.Text.Internal.Encoding.Fusion.Common ( Data/Text/Internal/Encoding/Fusion/Common.hs, dist/build/Data/Text/Internal/Encoding/Fusion/Common.o ) [21 of 43] Compiling Data.Text.Internal.Encoding.Utf8 ( Data/Text/Internal/Encoding/Utf8.hs, dist/build/Data/Text/Internal/Encoding/Utf8.o ) [22 of 43] Compiling Data.Text.Internal.Encoding.Fusion ( Data/Text/Internal/Encoding/Fusion.hs, dist/build/Data/Text/Internal/Encoding/Fusion.o ) [23 of 43] Compiling Data.Text.Internal.Lazy.Encoding.Fusion ( Data/Text/Internal/Lazy/Encoding/Fusion.hs, dist/build/Data/Text/Internal/Lazy/Encoding/Fusion.o ) [24 of 43] Compiling Data.Text.Internal.Search ( Data/Text/Internal/Search.hs, dist/build/Data/Text/Internal/Search.o ) [25 of 43] Compiling Data.Text ( Data/Text.hs, dist/build/Data/Text.o ) [26 of 43] Compiling Data.Text.Encoding ( Data/Text/Encoding.hs, dist/build/Data/Text/Encoding.o ) [27 of 43] Compiling Data.Text.Foreign ( Data/Text/Foreign.hs, dist/build/Data/Text/Foreign.o ) [28 of 43] Compiling Data.Text.Internal.IO ( Data/Text/Internal/IO.hs, dist/build/Data/Text/Internal/IO.o ) [29 of 43] Compiling Data.Text.IO ( Data/Text/IO.hs, dist/build/Data/Text/IO.o ) [30 of 43] Compiling Data.Text.Internal.Lazy ( Data/Text/Internal/Lazy.hs, dist/build/Data/Text/Internal/Lazy.o ) [31 of 43] Compiling Data.Text.Internal.Lazy.Fusion ( Data/Text/Internal/Lazy/Fusion.hs, dist/build/Data/Text/Internal/Lazy/Fusion.o ) [32 of 43] Compiling Data.Text.Internal.Lazy.Search ( Data/Text/Internal/Lazy/Search.hs, dist/build/Data/Text/Internal/Lazy/Search.o ) [33 of 43] Compiling Data.Text.Lazy.Internal ( Data/Text/Lazy/Internal.hs, dist/build/Data/Text/Lazy/Internal.o ) [34 of 43] Compiling Data.Text.Lazy ( Data/Text/Lazy.hs, dist/build/Data/Text/Lazy.o ) [35 of 43] Compiling Data.Text.Internal.Builder ( Data/Text/Internal/Builder.hs, dist/build/Data/Text/Internal/Builder.o ) [36 of 43] Compiling Data.Text.Lazy.Builder ( Data/Text/Lazy/Builder.hs, dist/build/Data/Text/Lazy/Builder.o ) [37 of 43] Compiling Data.Text.Internal.Builder.Functions ( Data/Text/Internal/Builder/Functions.hs, dist/build/Data/Text/Internal/Builder/Functions.o ) [38 of 43] Compiling Data.Text.Lazy.Builder.Int ( Data/Text/Lazy/Builder/Int.hs, dist/build/Data/Text/Lazy/Builder/Int.o ) [39 of 43] Compiling Data.Text.Lazy.IO ( Data/Text/Lazy/IO.hs, dist/build/Data/Text/Lazy/IO.o ) [40 of 43] Compiling Data.Text.Lazy.Read ( Data/Text/Lazy/Read.hs, dist/build/Data/Text/Lazy/Read.o ) [41 of 43] Compiling Data.Text.Lazy.Builder.RealFloat ( Data/Text/Lazy/Builder/RealFloat.hs, dist/build/Data/Text/Lazy/Builder/RealFloat.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.8.4 for i386-unknown-linux): RegAlloc.Liveness.computeLivenss SCCs aren't in reverse dependent order bad blockId c8xHd [NONREC c8xHG: jmp *-4(%ebx), NONREC c8xHF: movl $12,828(%ebx) jmp *stg_gc_unpt_r1@got(%vI_n8Wmo), NONREC c8xHE: movl %vI_n8Wmo,%vI_n8WmH addl $sat_s8qTs{v}_info@gotoff,%vI_n8WmH movl %vI_n8WmH,-8(%edi) movl 4(%ebp),%vI_n8WmI movl %vI_n8WmI,-4(%edi) movl 16(%ebp),%vI_n8WmJ movl %vI_n8WmJ,(%edi) leal -7(%edi),%esi addl $20,%ebp jmp *(%ebp), NONREC c8xHz: movl $48,828(%ebx) movl %vI_n8Wmo,%vI_n8WmF addl $block{v c8xEh}_info@gotoff,%vI_n8WmF movl %vI_n8WmF,(%ebp) movl %vI_s8qTz,%esi movl %vI_s8qTx,4(%ebp) jmp *stg_gc_unbx_r1@got(%vI_n8Wmo), NONREC c8xHq: movl %vI_c8xEw,%esi incl 8(%ebp) addl $8,%ebp jmp *stg_ap_n_fast@got(%vI_n8Wmo), NONREC c8xHp: movl %vI_c8xEw,%esi addl $8,%ebp jmp *stg_ap_n_fast@got(%vI_n8Wmo), NONREC c8xHi: jmp *(%esi), NONREC c8xGZ: call 1f 1: popl %vI_n8Wmo addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %vI_n8Wmo movl 4(%ebp),%vI_c8xEw movl %esi,%vI_n8Wmw andl $3,%vI_n8Wmw cmpl $2,%vI_n8Wmw jae _c8xHp jmp _c8xHq, NONREC c8xHy: movl %vI_n8Wmo,%vI_n8Wmy addl $lvl65{v s8qTB}_info@gotoff,%vI_n8Wmy movl %vI_n8Wmy,-44(%edi) movl %vI_s8qTz,-36(%edi) movl %vI_n8Wmo,%vI_n8WmA addl $a28{v s8qTD}_info@gotoff,%vI_n8WmA movl %vI_n8WmA,-32(%edi) movl %vI_s8qTd,-28(%edi) movl %vI_s8qTh,-24(%edi) movl %vI_s8qTk,-20(%edi) movl %vI_s8qTx,-16(%edi) leal -44(%edi),%vI_c8xEn movl %vI_c8xEn,-12(%edi) movl %vI_s8qRK,-8(%edi) movl %vI_s8qTj,-4(%edi) movl %vI_s8qTz,(%edi) movl %vI_n8Wmo,%vI_n8WmC addl $block{v c8xGZ}_info@gotoff,%vI_n8WmC movl %vI_n8WmC,16(%ebp) movl %vI_c8xEn,%esi leal -30(%edi),%vI_n8WmD movl %vI_n8WmD,20(%ebp) addl $16,%ebp testl $3,%esi jne _c8xGZ jmp _c8xHi, NONREC c8xGX: addl $12,%edi cmpl 804(%ebx),%edi ja _c8xHF jmp _c8xHE, NONREC c8xEi: addl $48,%edi cmpl 804(%ebx),%edi ja _c8xHz jmp _c8xHy, NONREC c8xHe: movl %esi,%vI_s8qTx movl $65533,%vI_s8qTz jmp _c8xEi, NONREC c8xEh: call 1f 1: popl %vI_n8Wmo addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %vI_n8Wmo movl 20(%ebp),%vI_s8qRK movl 12(%ebp),%vI_s8qTd movl 16(%ebp),%vI_s8qTh movl 24(%ebp),%vI_s8qTj movl 8(%ebp),%vI_s8qTk movl 4(%ebp),%vI_s8qTx movl %esi,%vI_s8qTz jmp _c8xEi, NONREC c8xEb: jmp *(%esi), NONREC c8xEa: call 1f 1: popl %vI_n8Wmo addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %vI_n8Wmo movl 20(%ebp),%vI_s8qRK movl 12(%ebp),%vI_s8qTd movl 16(%ebp),%vI_s8qTh movl 24(%ebp),%vI_s8qTj movl 8(%ebp),%vI_s8qTk movl 4(%ebp),%vI_s8qTw movl %vI_s8qTw,%vI_n8Wms andl $2095104,%vI_n8Wms cmpl $55296,%vI_n8Wms jne _c8xHd jmp _c8xHe, NONREC c8xE6: jmp *(%esi), NONREC c8xE5: call 1f 1: popl %vI_n8Wmo addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %vI_n8Wmo movl %vI_n8Wmo,%vI_n8Wmq addl $block{v c8xEa}_info@gotoff,%vI_n8Wmq movl %vI_n8Wmq,(%ebp) movl 3(%esi),%vI_s8qTw movl 4(%ebp),%esi movl %vI_s8qTw,4(%ebp) testl $3,%esi jne _c8xEa jmp _c8xEb, NONREC c8xGW: movl %vI_n8Wmo,%vI_n8Wmu addl $block{v c8xE5}_info@gotoff,%vI_n8Wmu movl %vI_n8Wmu,-8(%ebp) movl %esi,%vI_s8qTk movl 6(%esi),%vI_s8qTu movl 2(%esi),%esi movl %vI_s8qTu,-4(%ebp) movl %vI_s8qTk,(%ebp) addl $-8,%ebp testl $3,%esi jne _c8xE5 jmp _c8xE6, NONREC c8xDC: jmp *(%esi), NONREC c8xDB: call 1f 1: popl %vI_n8Wmo addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %vI_n8Wmo movl %esi,%vI_n8Wmn andl $3,%vI_n8Wmn cmpl $2,%vI_n8Wmn jae _c8xGW jmp _c8xGX, NONREC c8xHH: movl %vI_n8Wmo,%vI_n8WmL addl $block{v c8xDB}_info@gotoff,%vI_n8WmL movl %vI_n8WmL,-12(%ebp) movl %esi,%vI_s8qTh movl 2(%esi),%vI_s8qTd movl 6(%esi),%vI_s8qRK movl (%ebp),%esi movl %vI_s8qTd,-8(%ebp) movl %vI_s8qTh,-4(%ebp) movl %vI_s8qRK,(%ebp) addl $-12,%ebp testl $3,%esi jne _c8xDB jmp _c8xDC, NONREC c8xGY: call 1f 1: popl %vI_n8Wmo addl $_GLOBAL_OFFSET_TABLE_+(.-1b), %vI_n8Wmo leal -20(%ebp),%vI_n8Wml cmpl 796(%ebx),%vI_n8Wml jb _c8xHG jmp _c8xHH] }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10187> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10173: Panic: Irrefutable pattern failed for pattern Data.Maybe.Just
by GHC 14 Feb '19

14 Feb '19

#10173: Panic: Irrefutable pattern failed for pattern Data.Maybe.Just -----------------------------------+--------------------------------------- Reporter: mietek | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: Compile-time crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -----------------------------------+--------------------------------------- On 32-bit Red Hat Enterprise Linux 6.5, released on 11/11/2014 (available on [https://aws.amazon.com/marketplace/pp/B007NMF9O0/ Amazon EC2]), building `attoparsec-0.12.1.2` with GHC 7.8.4 causes a panic: {{{ Configuring attoparsec-0.12.1.2... Building attoparsec-0.12.1.2... Preprocessing library attoparsec-0.12.1.2... [ 1 of 21] Compiling Data.Attoparsec.Text.FastSet ( Data/Attoparsec/Text/FastSet.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Text/FastSet.o ) [ 2 of 21] Compiling Data.Attoparsec.Text.Buffer ( Data/Attoparsec/Text/Buffer.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Text/Buffer.o ) [ 3 of 21] Compiling Data.Attoparsec.Internal.Fhthagn ( Data/Attoparsec/Internal/Fhthagn.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Internal/Fhthagn.o ) [ 4 of 21] Compiling Data.Attoparsec.ByteString.Buffer ( Data/Attoparsec/ByteString/Buffer.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/ByteString/Buffer.o ) [ 5 of 21] Compiling Data.Attoparsec.Zepto ( Data/Attoparsec/Zepto.hs, dist/dist-sandbox-a9165fb6/build/Data/Attoparsec/Zepto.o ) [ 6 of 21] Compiling Data.Attoparsec.Number ( Data/Attoparsec/Number.hs, dist/dist-sandbox-a9165fb6/build/Data/Attoparsec/Number.o ) [ 7 of 21] Compiling Data.Attoparsec.ByteString.FastSet ( Data/Attoparsec/ByteString/FastSet.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/ByteString/FastSet.o ) [ 8 of 21] Compiling Data.Attoparsec.Internal.Types ( Data/Attoparsec/Internal/Types.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Internal/Types.o ) [ 9 of 21] Compiling Data.Attoparsec.Types ( Data/Attoparsec/Types.hs, dist/dist-sandbox-a9165fb6/build/Data/Attoparsec/Types.o ) [10 of 21] Compiling Data.Attoparsec.Internal ( Data/Attoparsec/Internal.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Internal.o ) [11 of 21] Compiling Data.Attoparsec.Combinator ( Data/Attoparsec/Combinator.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Combinator.o ) [12 of 21] Compiling Data.Attoparsec.ByteString.Internal ( Data/Attoparsec/ByteString/Internal.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/ByteString/Internal.o ) [13 of 21] Compiling Data.Attoparsec.Text.Internal ( Data/Attoparsec/Text/Internal.hs, dist/dist-sandbox- a9165fb6/build/Data/Attoparsec/Text/Internal.o ) ghc: panic! (the 'impossible' happened) (GHC version 7.8.4 for i386-unknown-linux): compiler/nativeGen/RegAlloc/Linear/JoinToTargets.hs:84:13-59: Irrefutable pattern failed for pattern Data.Maybe.Just live_set }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10173> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9277: GHCi panic: Loading temp shared object failed: Symbol not found
by GHC 14 Feb '19

14 Feb '19

#9277: GHCi panic: Loading temp shared object failed: Symbol not found ----------------------------------+--------------------------------- Reporter: mietek | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.8.2 Keywords: | Operating System: MacOS X Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #9034, #8935 | ----------------------------------+--------------------------------- When given a Objective-C object file referencing a symbol available in a system framework, GHCi panics saying it can't find the symbol the object file relies on. {{{ $ cat >foo.m <<EOF #import <Foundation/Foundation.h> BOOL is_main_thread() { return [NSThread isMainThread]; } EOF }}} {{{ $ clang -c -o foo.o foo.m }}} {{{ $ ghci -v -framework Foundation foo.o GHCi, version 7.8.2: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.8.2, stage 2 booted by GHC version 7.6.3 Using binary package database: /opt/ghc-7.8.2/lib/ghc-7.8.2/package.conf.d/package.cache wired-in package ghc-prim mapped to ghc- prim-0.3.1.0-948744e1f99cc8bcc7c7d3ba60c7c2d8 wired-in package integer-gmp mapped to integer- gmp-0.5.1.0-dc47f6b546fc171f67a7f7d311684a99 wired-in package base mapped to base-4.7.0.0-a333addb6892f3cc2e6baa5ec782bd04 wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template- haskell-2.9.0.0-ed6ecfb467e6936688bb20f968f702e1 wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. *** gcc: /usr/bin/gcc -m64 -fno-stack-protector -DTABLES_NEXT_TO_CODE -L/opt/ghc-7.8.2/lib/ghc-7.8.2/base-4.7.0.0 --print-file-name libiconv.dylib Loading package base ... linking ... done. Loading object (static) foo.o ... Created temporary directory: /var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0 *** Linker: /usr/bin/gcc -m64 -fno-stack-protector -DTABLES_NEXT_TO_CODE -m64 -dynamiclib -o /var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0/ghc36377_1.dylib foo.o -undefined dynamic_lookup -single_module -install_name '@rpath/ghc36377_1.dylib' -L/opt/ghc-7.8.2/lib/ghc-7.8.2/base-4.7.0.0 -Wl,-rpath -Wl,/opt/ghc-7.8.2/lib/ghc-7.8.2/base-4.7.0.0 -L/opt/ghc-7.8.2/lib/ghc-7.8.2/integer-gmp-0.5.1.0 -Wl,-rpath -Wl,/opt/ghc-7.8.2/lib/ghc-7.8.2/integer-gmp-0.5.1.0 -L/opt/ghc-7.8.2/lib/ghc-7.8.2/ghc-prim-0.3.1.0 -Wl,-rpath -Wl,/opt/ghc-7.8.2/lib/ghc-7.8.2/ghc-prim-0.3.1.0 -L/opt/ghc-7.8.2/lib/ghc-7.8.2/rts-1.0 -Wl,-rpath -Wl,/opt/ghc-7.8.2/lib/ghc-7.8.2/rts-1.0 -lHSbase-4.7.0.0-ghc7.8.2 -lHSinteger-gmp-0.5.1.0-ghc7.8.2 -lHSghc-prim-0.3.1.0-ghc7.8.2 -liconv *** Deleting temp files: Deleting: /var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0/ghc36377_1.dylib *** Deleting temp dirs: Deleting: /var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0 ghc: panic! (the 'impossible' happened) (GHC version 7.8.2 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0/ghc36377_1.dylib, 9): Symbol not found: _OBJC_CLASS_$_NSThread Referenced from: /var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0/ghc36377_1.dylib Expected in: flat namespace in /var/folders/26/0tzj1txn0vb_0061l4z4rsmr0000gn/T/ghc36377_0/ghc36377_1.dylib Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Note omitting `-framework Foundation` makes no difference to the output. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9277> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13595: Should ‘coerce’ be levity polymorphic?
by GHC 14 Feb '19

14 Feb '19

#13595: Should ‘coerce’ be levity polymorphic? -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) 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: #13592 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I'm not able to write `coerce @Int# @Int#` or `coerce :: Double# -> Double#`, just checking to see if its intentional or not {{{ >>> :set -XTypeApplications >>> :set -XMagicHash >>> import Data.Coerce >>> import GHC.Exts >>>> :t coerce @Int coerce @Int :: Coercible b Int => Int -> b >>> :t coerce @Int# <interactive>:1:1: error: Couldn't match a lifted type with an unlifted type When matching types b :: * Int# :: TYPE 'IntRep <interactive>:1:9: error: • Expecting a lifted type, but ‘Int#’ is unlifted • In the type ‘Int#’ In the expression: coerce @Int# }}} This was needed for #13592. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13595> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14848: -XDuplicateRecordFields breaks record expression splices
by GHC 10 Feb '19

10 Feb '19

#14848: -XDuplicateRecordFields breaks record expression splices -------------------------------------+------------------------------------- Reporter: dailectic | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: GHC rejects (amd64) | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ {-# language TemplateHaskell #-} {-# language DuplicateRecordFields #-} module Lib where import Language.Haskell.TH import Language.Haskell.TH.Syntax data A = A {x :: Int, y :: String} a = A 3 "test" test = $([e|case a of A {x = b} -> b|]) }}} Without `DuplicateRecordFields` it compiles correctly so `test = 3` but with `DuplicateRecordFields` enabled it gives: {{{ • Illegal variable name: ‘$sel:x:A’ When splicing a TH expression: case Lib.a of (Lib.A {Lib.$sel:x:A = b_0}) -> b_0 • In the untyped splice: $([| case a of { A {x = b} -> b } |]) }}} Additionally, there doesn't seem to be a workaround for munging the name manually, since the `$sel:x:A` name is the one actually in scope, there is no `A.x` like there would be normally, even when the label is not a duplicate. Is there a way to get around this? Ex: by changing the binding name somehow manually? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14848> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15091: Better occurrence analysis for join points
by GHC 10 Feb '19

10 Feb '19

#15091: Better occurrence analysis for join points -------------------------------------+------------------------------------- Reporter: simonpj | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.2.2 Keywords: JoinPoints | 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 this {{{ let x = ... in join j y = x+y in case v of A -> x B -> j 1 C -> j 2 D -> 3 }}} What does `OccAnal` say about `x`'s usage? It says `ManyOccs`! But it's plain as a pikestaff that `x` is used at most once: * Either in the `A` branch, * or in the `B` or `C` branches via `j`. If instead we had inlined `j` we'd have {{{ let x = ... in join j y = x+y in case v of A -> x B -> x + 1 C -> x + 2 D -> 3 }}} and now it's all more obvious: `x`'s occurrence info should be `OneOcc { occ_one_br = False }`, not `ManyOccs`. Does this matter? Not a great deal, but there is a reason for having `OneOcc` with `occ_one_br = False`, and it seems a shame not to take advantage. One case in point is the definition of `SimplUtils.isExitJoinId {{{ isExitJoinId :: Var -> Bool isExitJoinId id = isJoinId id && isOneOcc (idOccInfo id) && occ_in_lam (idOccInfo id) }}} Something does not cease to be an exit-join-point if it is mentioned in multiple places as above. Another use for this info is `postInlineUnconditionally`. Could we improve this situation? I think it'd be quite easy. For non- recursive join points `j = rhs` * Gather occurrence info from the RHS * Bind `j` to its occurrence info * Unleash that occurrence info at each jump-site for `j`, just as if it had been inlined. See Trac #14152, comment:40. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15091> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12658: GHC 7.10.3 sometimes reports unimplemented/strange closure type 63270
by GHC 09 Feb '19

09 Feb '19

#12658: GHC 7.10.3 sometimes reports unimplemented/strange closure type 63270 --------------------------------+--------------------------------------- Reporter: clint | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Linux Architecture: powerpc | Type of failure: Compile-time crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: --------------------------------+--------------------------------------- This happened when building http-link-header. {{{ ghc: internal error: scavenge: unimplemented/strange closure type 63270 @ 0xf36de0a8ghc: internal error: scavenge: unimplemented/strange closure type 63270 @ 0xf36de0a8 (GHC version 7.10.3 for powerpc_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Sometimes it segfaults instead. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12658> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9370: large blowup in memory usage and time when doing parallel build of xmlhtml package
by GHC 08 Feb '19

08 Feb '19

#9370: large blowup in memory usage and time when doing parallel build of xmlhtml package -------------------------------------+------------------------------------- Reporter: carter | 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: -------------------------------------+------------------------------------- I've observed a blowup in ghc memory usage when invoked with parallel build flags. to reproduce {{{ cabal get xmlhtml-0.2.3.2 cabal install xmlhtml-0.2.3.2 --only-dependencies cd xmlhtml-0.2.3.2 }}} then {{{ cabal clean ; cabal configure --ghc-options="-j4" ; time cabal build -j4 -v3 }}} will take quite a while and use > 1gb of ram whereas {{{ cabal clean ; cabal configure --ghc-options="-j1 ; time cabal build -j1 -v3 }}} will use < 150mb of ram. Based upon the output of cabal build -j4 -v3, it looks like the parallel build is spending a lottt more time in the simplifier passes. I'm not sure what changes between the parallel and sequential builds to change this. I'll try to dig into this more in a few days, but recording this problem now before i forget. (though of course any insights would be appreciated) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9370> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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