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[GHC] #8854: Missing class method not caught at compile time, program freezes when missing method is called.
by GHC 06 Mar '14

06 Mar '14

#8854: Missing class method not caught at compile time, program freezes when missing method is called. ----------------------------------+---------------------------------- Reporter: RaminHAL9001 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: Runtime crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #7633 | ----------------------------------+---------------------------------- I created a type class where two of four functions must be satisfied for a minimal complete definition. GHC did not catch an instance where the minimal complete definition was not satisfied, the program compiled without an error or warning. When running the compiled program it would freeze when calling the missing method. Also when running the program in GHCi and stepping up to the use of the missing method, GHCi would freeze before reaching the missing function. This made it very difficult to debug. It '''did not''' throw a "NoMethodError" exception, and there '''was no''' segment violation caught by the operating system, nor does the program terminate with the "<<loop>>" message output on the command line. Compiling with language extensions: {{{ -XTemplateHaskell -XScopedTypeVariables -XRankNTypes -XMultiParamTypeClasses -XFunctionalDependencies -XFlexibleInstances -XFlexibleContexts -XDeriveDataTypeable }}} Using compiler flags: {{{ -prof -fprof-auto -threaded -Wall -fno-warn-name-shadowing -fno-warn- unused-do-bind -fno-warn-auto-orphans }}} '''To Reproduce the Issue''' I tried to reproduce the issue with a miniature program that isolates the problem, but GHC successfully detects a problem and terminates with the "<<loop>>" message written on the command line. My program is much larger and simply froze. However the code I wrote looks similar to the following situation... First I tried this, which gave me no problems at all: {{{ class A x where f1 :: x f1 = f2 f2 :: x f2 = f1 }}} We have two functions f1 and f2, if f1 is not defined it defaults to f2, if f2 is not defined it defaults to f1, so you must define either f1 or f2, or you could also define both. Then I add two more methods: {{{ class A x where f1 :: x f1 = f2 f2 :: x f2 = f1 g1 :: x g1 = g2 g2 :: x g2 = g1 }}} Just like with f1 f2, the g1 g2 functions each use their counterpart to define their default method. But this caused a huge problem. The minimal complete definition should be (f1 | f2) & (g1 | g2), but the compiler does not report any warning when I have not satisfied the minimal complete definition. Maybe one of my compiler flags disabled a would-be warning, I don't know yet. This was a red-flag to me, but I went on to test my program. As it turns out, there was a place in my code where I forgot to write an instance for g1 or g2 but I had not realize it. I only found out when I ran my test program and it froze. No "unsatisfied method" exception, not segment violations, it just froze. Although the program was still running and consuming a small amount of CPU resources, and I could cancel with CTRL-C in the command line. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8854> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5925: Add inline version of newArray#
by GHC 06 Mar '14

06 Mar '14

#5925: Add inline version of newArray# -------------------------------------+------------------------------------ Reporter: tibbe | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: 4258 Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by tibbe): I've done some work on this branch: [https://github.com/tibbe/ghc/tree /alloc-inline]. I've also attached the changes to this ticket so they don't get lost if I lose the branch. The current status is that I have something that seems to generate the assembly I want, but I haven't managed to write a benchmark that shows any speed-up, even though I've eliminated two branches and one function call, if I recall correctly. So the task at this point is to come up with some good benchmarks. There are essentially two ways to attack that problem. Either we can try to show a speed-up in allocation or we can try to show a speed-up due to the better locality (e.g. constructor wrapping an array can now be allocated next to the array.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5925#comment:12> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #5925: Add inline version of newArray#
by GHC 06 Mar '14

06 Mar '14

#5925: Add inline version of newArray# -------------------------------------+------------------------------------ Reporter: tibbe | Owner: Type: feature request | Status: new Priority: normal | Milestone: 7.6.2 Component: Compiler | Version: 7.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: 4258 Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by jberryman): * cc: brandon.m.simmons@… (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5925#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3693: Show stack traces
by GHC 06 Mar '14

06 Mar '14

#3693: Show stack traces -------------------------------------+------------------------------------ Reporter: jpet | Owner: Tarrasch Type: feature request | Status: new Priority: normal | Milestone: 7.10.1 Component: Runtime System | Version: 6.10.4 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by simonpj): Simon M and I took a look today. We added a few notes to the github thing https://github.com/scpmw/ghc/commit/d233ea4da0a5725d4d29a3fb68b9b8f7c9bc6d32 #diff-8b5b79c6cb1af2b387fa2d814cd0d3f6R1638 The major stumbling block is giving a really clear description of what each of the various predicates on ticks means: `tickishScoped`, `tickishSoftScoped`, `tickishCounts`, `tickishIsCode` etc. We might want to rename some of them. Eg `tickisScoped` and `tickishSoftScoped` might be replaced by `canFloatCodeInsideThisTick` and `canFloatCodeOutsideThisTick`, perhaps. Each call site has asks a question about the equivalence of two pieces of code, and the predicates should probably have an example drawn from every call site. That might make the correct generalisation clear. Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3693#comment:67> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #8024: Dynamic linking not working on PowerPC Linux.
by GHC 05 Mar '14

05 Mar '14

#8024: Dynamic linking not working on PowerPC Linux. ----------------------------------------+--------------------------- Reporter: erikd | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Linux | Architecture: powerpc Type of failure: Building GHC failed | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ----------------------------------------+--------------------------- Comment (by erikd): In mk/config.mk.in tried changing {{{ PIC = pic }}} to {{{ PIC = PIC }}} ran the whole process from `perl boot` onwards and that didn't help. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8024#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8846: GHC panic with Template Haskell
by GHC 05 Mar '14

05 Mar '14

#8846: GHC panic with Template Haskell ----------------------------------+--------------------------------------- Reporter: Gothmog | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: Compile-time crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+--------------------------------------- I get a panic when compiling the attached files with "ghc --make test": ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for x86_64-unknown-linux): nameModule a{v a14p} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8846> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8820: 7.8 RC1 unregisterised fails selfbootstrap on 64 bit Linux
by GHC 04 Mar '14

04 Mar '14

#8820: 7.8 RC1 unregisterised fails selfbootstrap on 64 bit Linux ----------------------------------+---------------------------------------- Reporter: trommler | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.1-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Building GHC failed Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: #8819 | ----------------------------------+---------------------------------------- Selfbootstrap of an unregisterised ghc fails on 64 bit PowerPC and AMD but not on 32 bit (PowerPC or Intel): {{{ [10021s] "inplace/bin/ghc-stage1" -static -H32m -O -optc-mminimal-toc -optc-fno-builtin -Iincludes -Iincludes/dist -Iincludes/dist- derivedconstants/header -Iincludes/dist-ghcconstants/header -Irts -Irts/dist/build -DCOMPILING_RTS -package-name rts -optc-DNOSMP -dcmm-lint -i -irts -irts/dist/build -irts/dist/build/autogen -Irts/dist/build -Irts/dist/build/autogen -O2 -c rts/StgStartup.cmm -o rts/dist/build/StgStartup.o [10021s] ghc-stage1: panic! (the 'impossible' happened) [10021s] (GHC version 7.8.0.20140220 for powerpc64-unknown-linux): [10021s] no ppt [10021s] ct ct: _cj::P64 = P64[(old + 16)]; [10021s] _ck::P64 = R1; [10021s] goto cl; [10021s] [10021s] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} I disabled gcc's built in functions through {{{-fno-builtin}}} which got rid of a load of warnings (incompatible types for the built-ins) but still fails as shown above. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8820> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8847: Int64 ^ Int64 broken by optimization on SPARC
by GHC 04 Mar '14

04 Mar '14

#8847: Int64 ^ Int64 broken by optimization on SPARC --------------------------+------------------------------------------------ Reporter: | Owner: kgardas | Status: new Type: bug | Milestone: Priority: normal | Version: Component: | Operating System: Solaris Compiler (NCG) | Type of failure: Incorrect result at runtime Keywords: | Test Case: Architecture: sparc | Blocking: Difficulty: | Unknown | Blocked By: | Related Tickets: | --------------------------+------------------------------------------------ The T7507 test is broken on SPARC NCG, I've more simplified it to {{{ module Main where import Data.Int main = print ( ( 2 :: Int64 ) ^ ( 6 :: Int64 ) ) }}} it does not matter if it's run with two Int64 or just with one: {{{ main = print ( 2 ^ 6 :: Int64 ) }}} the result with -O is still 0. The result without -O is correct. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8847> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8845: weight lose tips 2071
by GHC 04 Mar '14

04 Mar '14

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Re: [GHC] #7452: [GNU gold] ld: error: cannot find [...]/Types__1.o
by GHC 04 Mar '14

04 Mar '14

#7452: [GNU gold] ld: error: cannot find [...]/Types__1.o ----------------------------------------+---------------------------------- Reporter: mrothe | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.1 Component: Build System | Version: 7.6.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 (amd64) Type of failure: Building GHC failed | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ----------------------------------------+---------------------------------- Comment (by octoploid): See: https://sourceware.org/bugzilla/show_bug.cgi?id=16341 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7452#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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