June 2017 - ghc-tickets

[GHC] #8494: Warn if a pattern guard obviates all others
by GHC 03 May '18

03 May '18

#8494: Warn if a pattern guard obviates all others -------------------------+------------------------------------------------- Reporter: | Owner: JohnWiegley | Status: new Type: | Milestone: feature request | Version: 7.6.3 Priority: | Operating System: Unknown/Multiple normal | Type of failure: Incorrect warning at Component: | compile-time Compiler | Test Case: Keywords: | Blocking: Architecture: | Unknown/Multiple | Difficulty: | Unknown | Blocked By: | Related Tickets: | -------------------------+------------------------------------------------- The following code, when compiled with `-Wall`, gives no warnings: {{{ module Main where main :: IO () main = print $ foo (10 :: Int) where foo x | True = (20 :: Int) | x == 10 = (30 :: Int) }}} I would expect that since the pattern guard `| True` obviates the following guards, that it would warn about unreachable code. There was a bug in my code today which I tracked down to a code transposition that would have been easily spotted with such a warning. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8494> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9951: OverloadedLists breaks exhaustiveness check
by GHC 03 May '18

03 May '18

#9951: OverloadedLists breaks exhaustiveness check -------------------------------------+------------------------------------- Reporter: Feuerbach | 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: | -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE OverloadedLists #-} module Bug where f :: [a] -> () f x = case x of [] -> () (_:_) -> () }}} GHC reports: {{{ bug.hs:6:7: Warning: Pattern match(es) are non-exhaustive In a case alternative: Patterns not matched: [] }}} This is reproducible with 7.8 and 7.10rc1. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9951> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10116: Closed type families: Warn if it doesn't handle all cases
by GHC 03 May '18

03 May '18

#10116: Closed type families: Warn if it doesn't handle all cases -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: Type: task | 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: | -------------------------------------+------------------------------------- Right now, I can do the following: data Foo = A | B type family Bar (n :: 'Foo) where Bar 'A = Int I would like to be warned if I write a partial type function like this because partial functions are almost always a mistake. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10116> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10393: Bogus warning with OverloadedLists
by GHC 03 May '18

03 May '18

#10393: Bogus warning with OverloadedLists -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- When I say {{{ {-# LANGUAGE OverloadedLists #-} lgo :: [a] -> () lgo [] = () lgo (_:_) = () }}} I get {{{ /Users/rae/temp/Bug.hs:4:1: Warning: Pattern match(es) are non-exhaustive In an equation for ‘lgo’: Patterns not matched: [] }}} I don't know !OverloadedLists deeply, but that warning surely is confusing! Happens on both 7.8.3 and 7.10.1. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10393> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13091: Build broken on amd64 solaris 11
by GHC 02 May '18

02 May '18

#13091: Build broken on amd64 solaris 11 -------------------------------------+------------------------------------- Reporter: kgardas | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build System | Version: 8.0.2 Keywords: | Operating System: Solaris Architecture: x86_64 | Type of failure: Building GHC (amd64) | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ ===--- building phase 1 gmake --no-print-directory -f ghc.mk phase=1 phase_1_builds libraries/hpc/ghc.mk:3: libraries/hpc/dist-boot/build/.depend-v.haskell: No such file or directory compiler/ghc.mk:584: compiler/stage1/build/.depend-v.haskell: No such file or directory "/opt/ghc-7.10.2-amd64/bin/ghc" -hisuf hi -osuf o -hcsuf hc -static -H32m -O -Wall -package-db libraries/bootstrapping.conf -hide-all- packages -i -iutils/hsc2hs/. -iutils/hsc2hs/dist/build -iutils/hsc2hs/dist/build/autogen -Iutils/hsc2hs/dist/build -Iutils/hsc2hs/dist/build/autogen -optP-include -optPutils/hsc2hs/dist/build/autogen/cabal_macros.h -package-id base-4.8.1.0-bcc57434d4c4ded429bd4c7561dc7931 -package-id containers-0.5.6.2-3bd9811190df2d727713a53a0942b5c9 -package-id directory-1.2.2.0-17006ecadb146c26f40f44f8704a6547 -package-id filepath-1.4.0.0-8fee9c13b5e42926cc01f6aa7c403c4b -package-id process-1.2.3.0-47082ea082854427d5ceb7c692692d3c -XHaskell2010 -no-user- package-db -rtsopts -odir utils/hsc2hs/dist/build -hidir utils/hsc2hs/dist/build -stubdir utils/hsc2hs/dist/build -c utils/hsc2hs/./Main.hs -o utils/hsc2hs/dist/build/Main.o "/opt/ghc-7.10.2-amd64/bin/ghc" -o utils/hsc2hs/dist/build/tmp/hsc2hs -hisuf hi -osuf o -hcsuf hc -static -H32m -O -Wall -package-db libraries/bootstrapping.conf -hide-all-packages -i -iutils/hsc2hs/. -iutils/hsc2hs/dist/build -iutils/hsc2hs/dist/build/autogen -Iutils/hsc2hs/dist/build -Iutils/hsc2hs/dist/build/autogen -optP- include -optPutils/hsc2hs/dist/build/autogen/cabal_macros.h -package-id base-4.8.1.0-bcc57434d4c4ded429bd4c7561dc7931 -package-id containers-0.5.6.2-3bd9811190df2d727713a53a0942b5c9 -package-id directory-1.2.2.0-17006ecadb146c26f40f44f8704a6547 -package-id filepath-1.4.0.0-8fee9c13b5e42926cc01f6aa7c403c4b -package-id process-1.2.3.0-47082ea082854427d5ceb7c692692d3c -XHaskell2010 -no-user- package-db -rtsopts -odir utils/hsc2hs/dist/build -hidir utils/hsc2hs/dist/build -stubdir utils/hsc2hs/dist/build -optl-optl- Wl,-m64 -static -H32m -O -Wall -package-db libraries/bootstrapping.conf -hide-all-packages -i -iutils/hsc2hs/. -iutils/hsc2hs/dist/build -iutils/hsc2hs/dist/build/autogen -Iutils/hsc2hs/dist/build -Iutils/hsc2hs/dist/build/autogen -optP-include -optPutils/hsc2hs/dist/build/autogen/cabal_macros.h -package-id base-4.8.1.0-bcc57434d4c4ded429bd4c7561dc7931 -package-id containers-0.5.6.2-3bd9811190df2d727713a53a0942b5c9 -package-id directory-1.2.2.0-17006ecadb146c26f40f44f8704a6547 -package-id filepath-1.4.0.0-8fee9c13b5e42926cc01f6aa7c403c4b -package-id process-1.2.3.0-47082ea082854427d5ceb7c692692d3c -XHaskell2010 -no-user- package-db -rtsopts utils/hsc2hs/dist/build/Main.o utils/hsc2hs/dist/build/C.o utils/hsc2hs/dist/build/Common.o utils/hsc2hs/dist/build/CrossCodegen.o utils/hsc2hs/dist/build/DirectCodegen.o utils/hsc2hs/dist/build/Flags.o utils/hsc2hs/dist/build/HSCParser.o utils/hsc2hs/dist/build/UtilsCodegen.o utils/hsc2hs/dist/build/Paths_hsc2hs.o ld: fatal: option '-optl-Wl,-m64' and option '-outils/hsc2hs/dist/build/tmp/hsc2hs' are multiple definitions collect2: error: ld returned 1 exit status gmake[1]: *** [utils/hsc2hs/dist/build/tmp/hsc2hs] Error 1 gmake: *** [all] Error 2 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13091> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11352: Allow applying type to label
by GHC 02 May '18

02 May '18

#11352: Allow applying type to label -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | 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: -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE TypeApplications #-} {-# LANGUAGE OverloadedLabels #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE DataKinds #-} import GHC.TypeLits import GHC.OverloadedLabels instance IsLabel "answer" Int where fromLabel _ = 42 answer :: IsLabel "answer" a => a answer = #answer }}} The follow works: {{{#!hs >>> answer @Int 42 }}} but fails with a label: {{{#!hs >>> #answer @Int <interactive>:...:1: error: • Cannot not apply expression of type ‘t0’ to a visible type argument ‘Int’ • In the expression: #answer @Int In an equation for ‘it’: it = #answer @Int }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11352> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11323: powerpc64: recomp015 fails with redundant linking
by GHC 01 May '18

01 May '18

#11323: powerpc64: recomp015 fails with redundant linking -------------------------------------+------------------------------------- Reporter: trommler | Owner: trommler Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 7.11 Keywords: | Operating System: Linux Architecture: powerpc64 | Type of failure: Compile-time Test Case: | performance bug driver/recomp15 | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... Running main... +Linking Main ... Running main... }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11323> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13520: instance Alternative ZipList
by GHC 26 Apr '18

26 Apr '18

#13520: instance Alternative ZipList -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 8.0.1 libraries/base | 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 paper "From monoids to near-semirings: the essence of MonadPlus and Alternative`" mentions > Perhaps surprisingly, `ZipList`s have an `Alternative` instance. Like the `Alternative` instance for `Maybe`, the one for `ZipList` has a left bias. > > {{{#!hs > instance Alternative ZipList where > empty :: ZipList a > empty = ZL [] > > (<|>) :: ZipList a -> ZipList a -> ZipList a > ZL xs <|> ZL ys = ZL (xs ++ drop (length xs) ys) > }}} Has this been considered for base? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13520> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13876: Check 'pure' method of 'Applicative (WrappedMonad m)'
by GHC 26 Apr '18

26 Apr '18

#13876: Check 'pure' method of 'Applicative (WrappedMonad m)' -------------------------------------+------------------------------------- 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: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Should {{{#!hs instance Monad m => Applicative (WrappedMonad m) where pure = WrapMonad . pure WrapMonad f <*> WrapMonad v = WrapMonad (f `ap` v) }}} not use `return`? {{{#!hs instance Monad m => Applicative (WrappedMonad m) where pure = WrapMonad . return WrapMonad f <*> WrapMonad v = WrapMonad (f `ap` v) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13876> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8406: Invalid object in isRetainer() or Segfault
by GHC 25 Apr '18

25 Apr '18

#8406: Invalid object in isRetainer() or Segfault ----------------------------------+---------------------------------- Reporter: crockeea | 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: | ----------------------------------+---------------------------------- When compiling with -rtsopts -threaded -prof -fprof-auto -caf-all and running with -N4 -hr I get a "Segmentation fault" every time. If I run with -N4 -qg1 -hr, I either get a segfault or internal error: Invalid object in isRetainer(): 40 When the segfault happens, it happens quickly. If the segfault doesn't happen, the program runs for about 5 seconds and I get "invalid object" error (always 40). Without -hr, I have never gotten a segfault. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8406> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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