August 2018 - ghc-tickets

[GHC] #15570: Core transformations generate bad indexCharOffAddr# call
by GHC 04 Sep '18

04 Sep '18

#15570: Core transformations generate bad indexCharOffAddr# call -------------------------------------+------------------------------------- Reporter: alpmestan | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 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: -------------------------------------+------------------------------------- Consider the following functions, which only differ in a bang pattern on the local binding `q` in the inner loop: {{{#!hs {-# LANGUAGE BangPatterns #-} {-# LANGUAGE MagicHash #-} module Bug where import GHC.Prim import GHC.Types f :: Int -> String f n_ = go n_ "" where go n cs | n < 62 = let !c = chooseChar62 n in c : cs | otherwise = go q (c : cs) where (q, r) = quotRem n 62 !c = chooseChar62 r chooseChar62 :: Int -> Char {-# INLINE chooseChar62 #-} chooseChar62 (I# n) = C# (indexCharOffAddr# chars62 n) chars62 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"# g :: Int -> String g n_ = go n_ "" where go n cs | n < 62 = let !c = chooseChar62 n in c : cs | otherwise = go q (c : cs) where (!q, r) = quotRem n 62 -- !!! Note the bang on q !c = chooseChar62 r chooseChar62 :: Int -> Char {-# INLINE chooseChar62 #-} chooseChar62 (I# n) = C# (indexCharOffAddr# chars62 n) chars62 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"# }}} When building with `-O -fPIC -dynamic -ddump-simpl`, this is the Core I see, with a HEAD checkout from earlier this week built by hadrian: {{{#!hs -- chararacter array, used by both chars62_r30r :: Addr# chars62_r30r = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"# -- Used at the end of Bug.$wgo, in the -9223372036854775808# branch, -- therefore only used by generated Core for f, but not g! lvl_r30s :: Char lvl_r30s = case indexCharOffAddr# chars62_r30r -9223372036854775808# of v_B2 { __DEFAULT -> GHC.Types.C# v_B2 } -- Core for f Rec { Bug.$wgo :: Int# -> [Char] -> (# Char, [Char] #) Bug.$wgo = \ (ww_s2WU :: Int#) (w_s2WR :: [Char]) -> case GHC.Real.even3 of { I# y_a2QI -> -- GHC.Real.even3 == -1 case y_a2QI of { __DEFAULT -> case quotRemInt# ww_s2WU 62# of { (# ipv_a2QN, ipv1_a2QO #) -> case indexCharOffAddr# chars62_r30r ipv1_a2QO of wild2_X4 { __DEFAULT -> case <# ww_s2WU 62# of { __DEFAULT -> Bug.$wgo ipv_a2QN (GHC.Types.: @ Char (GHC.Types.C# wild2_X4) w_s2WR); 1# -> case indexCharOffAddr# chars62_r30r ww_s2WU of wild3_X1G { __DEFAULT -> (# GHC.Types.C# wild3_X1G, w_s2WR #) } } } }; 62# -> case ww_s2WU of wild2_a2QQ { __DEFAULT -> case quotRemInt# wild2_a2QQ 62# of { (# ipv_a2QT, ipv1_a2QU #) -> case indexCharOffAddr# chars62_r30r ipv1_a2QU of wild4_X4 { __DEFAULT -> case <# wild2_a2QQ 62# of { __DEFAULT -> Bug.$wgo ipv_a2QT (GHC.Types.: @ Char (GHC.Types.C# wild4_X4) w_s2WR); 1# -> case indexCharOffAddr# chars62_r30r wild2_a2QQ of wild5_X1G { __DEFAULT -> (# GHC.Types.C# wild5_X1G, w_s2WR #) } } } }; -9223372036854775808# -> case lvl_r30s of { C# v1_B2 -> (# GHC.Types.C# v1_B2, w_s2WR #) } } } } end Rec } Bug.f_go :: Int -> [Char] -> [Char] Bug.f_go = \ (w_s2WQ :: Int) (w1_s2WR :: [Char]) -> case w_s2WQ of { I# ww1_s2WU -> case Bug.$wgo ww1_s2WU w1_s2WR of { (# ww3_s2Xa, ww4_s2Xb #) -> GHC.Types.: @ Char ww3_s2Xa ww4_s2Xb } } f :: Int -> String f = \ (n__aXG :: Int) -> case n__aXG of { I# ww1_s2WU -> case Bug.$wgo ww1_s2WU (GHC.Types.[] @ Char) of { (# ww3_s2Xa, ww4_s2Xb #) -> GHC.Types.: @ Char ww3_s2Xa ww4_s2Xb } } -- Core for g Rec { Bug.$wgo1 :: Int# -> [Char] -> (# Char, [Char] #) Bug.$wgo1 = \ (ww_s2X4 :: Int#) (w_s2X1 :: [Char]) -> case GHC.Real.even3 of { I# y_a2QI -> case y_a2QI of { __DEFAULT -> case quotRemInt# ww_s2X4 62# of { (# ipv_a2QN, ipv1_a2QO #) -> case indexCharOffAddr# chars62_r30r ipv1_a2QO of wild2_X4 { __DEFAULT -> case <# ww_s2X4 62# of { __DEFAULT -> Bug.$wgo1 ipv_a2QN (GHC.Types.: @ Char (GHC.Types.C# wild2_X4) w_s2X1); 1# -> case indexCharOffAddr# chars62_r30r ww_s2X4 of wild3_XY { __DEFAULT -> (# GHC.Types.C# wild3_XY, w_s2X1 #) } } } }; 62# -> case ww_s2X4 of wild2_a2QQ { __DEFAULT -> case quotRemInt# wild2_a2QQ 62# of { (# ipv_a2QT, ipv1_a2QU #) -> case indexCharOffAddr# chars62_r30r ipv1_a2QU of wild4_X4 { __DEFAULT -> case <# wild2_a2QQ 62# of { __DEFAULT -> Bug.$wgo1 ipv_a2QT (GHC.Types.: @ Char (GHC.Types.C# wild4_X4) w_s2X1); 1# -> case indexCharOffAddr# chars62_r30r wild2_a2QQ of wild5_XY { __DEFAULT -> (# GHC.Types.C# wild5_XY, w_s2X1 #) } } } }; -9223372036854775808# -> case GHC.Real.overflowError of wild4_00 { } } } } end Rec } Bug.g_go :: Int -> [Char] -> [Char] Bug.g_go = \ (w_s2X0 :: Int) (w1_s2X1 :: [Char]) -> case w_s2X0 of { I# ww1_s2X4 -> case Bug.$wgo1 ww1_s2X4 w1_s2X1 of { (# ww3_s2Xd, ww4_s2Xe #) -> GHC.Types.: @ Char ww3_s2Xd ww4_s2Xe } } g :: Int -> String g = \ (n__a29X :: Int) -> case n__a29X of { I# ww1_s2X4 -> case Bug.$wgo1 ww1_s2X4 (GHC.Types.[] @ Char) of { (# ww3_s2Xd, ww4_s2Xe #) -> GHC.Types.: @ Char ww3_s2Xd ww4_s2Xe } } }}} Of particular interest is: {{{#!hs -- chararacter array, used by both chars62_r30r :: Addr# chars62_r30r = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"# lvl_r30s :: Char lvl_r30s = case indexCharOffAddr# chars62_r30r -9223372036854775808# of v_B2 { __DEFAULT -> GHC.Types.C# v_B2 } }}} which is only used in the Core for `f`, not `g`! We're trying to access index `minBound :: Int` of that array of chars. While this is only used when we pass `minBound` to our function, it is still wrong I think. Moreover, as [https://github.com/snowleopard/hadrian/issues/861 hadrian issue 861] showed, this can lead to... linker errors! Which got fixed by changing the implementation of `iToBase62` in Unique.hs from `f` to `g` :-) Note that when I build the same commit with the make build system, then GHC generates Core close to `g`'s above for _both functions_. I tried describing some of the transformations that occur in [https://github.com/snowleopard/hadrian/issues/641#issuecomment-415881512 this comment] on hadrian's issue tracker. The gist of it is that the lack of strictness in `q` leads GHC to not spotting it early and when we inline `quotRem`/`quotRemInt` and start floating things in/out and distributing `case ... of` branches around, we end up with a dedicated branch in the inner loop for `minBound` which actually makes use of the result of `indexAddrOffAddr#`, as you can see here: {{{#!hs -9223372036854775808# -> -- lvl_r30s is our bad value case lvl_r30s of { C# v1_B2 -> (# GHC.Types.C# v1_B2, w_s2WR #) } }}} whereas this is what this branch looks like for `g`: {{{#!hs -9223372036854775808# -> case GHC.Real.overflowError of wild4_00 { } }}} The `overflowError` is still there and GHC therefore realised that there's no point in computing anything since we always raise an overflow error in that branch. This `overflowError` just disappears in `f`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15570> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15586: Compilation panic! (the 'impossible' happened)
by GHC 04 Sep '18

04 Sep '18

#15586: Compilation panic! (the 'impossible' happened) -------------------------------------+------------------------------------- Reporter: subaruru | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Linux Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- See attached zip for entire project causing error. I'd imagine it's pretty reproducible, just call stack build. I'm running standard lts-12.8 and it's just two small files that don't do anything yet! Also included is panicmessage.txt showing the exact output, crucially: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.4.3 for x86_64-unknown-linux): piResultTy * v_XabT Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:947:35 in ghc:Type }}} Oh and sysinfo {{{ uname -a Linux @@@ 4.16.11-100.fc26.x86_64 #1 SMP Tue May 22 20:02:12 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15586> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13243: make test in non-validate configuration fails with a variety of ghci errors
by GHC 04 Sep '18

04 Sep '18

#13243: make test in non-validate configuration fails with a variety of ghci errors -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: GHCi | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Starting with a fresh checkout of `ghc`, testing in a non-validate configuration fails in a rather peculiar way. e.g., {{{ $ ./boot $ ./configure $ make $ make test }}} Results in a number of test failures of the `ghci` way which suggest that GHCi is having trouble identifying types. e.g., {{{ =====> break026(ghci) 50 of 101 [0, 46, 0] cd "./ghci.debugger/scripts/break026.run" && HC="/mnt/work/ghc/ghc- testing/inplace/test spaces/ghc-stage2" HC_OPTS="-dcore-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn-missed-specialisations -fshow- warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -dno- debug-output " "/mnt/work/ghc/ghc-testing/inplace/test spaces/ghc- stage2" -dcore-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn- missed-specialisations -fshow-warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -dno-debug-output --interactive -v0 -ignore- dot-ghci -fno-ghci-history +RTS -I0.1 -RTS -ignore-dot-ghci< break026.script Actual stderr output differs from expected: diff -uw "/dev/null" "./ghci.debugger/scripts/break026.run/break026.run.stderr.normalised" --- /dev/null 2017-01-24 15:20:36.872346204 -0500 +++ ./ghci.debugger/scripts/break026.run/break026.run.stderr.normalised 2017-02-08 15:52:09.290099692 -0500 @@ -0,0 +1,14 @@ + +<interactive>:16:1: + No instance for (Show t1) arising from a use of ‘print’ + Cannot resolve unknown runtime type ‘t1’ + Use :print or :force to determine these types + Relevant bindings include it :: t1 (bound at <interactive>:16:1) + These potential instances exist: + instance Show Ordering -- Defined in ‘GHC.Show’ + instance Show Integer -- Defined in ‘GHC.Show’ + instance Show a => Show (Maybe a) -- Defined in ‘GHC.Show’ + ...plus 22 others + ...plus 11 instances involving out-of-scope types + (use -fprint-potential-instances to see them all) + In a stmt of an interactive GHCi command: print it *** unexpected failure for break026(ghci) =====> break027(ghci) 51 of 101 [0, 47, 0] cd "./ghci.debugger/scripts/break027.run" && HC="/mnt/work/ghc/ghc- testing/inplace/test spaces/ghc-stage2" HC_OPTS="-dcore-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn-missed-specialisations -fshow- warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -dno- debug-output " "/mnt/work/ghc/ghc-testing/inplace/test spaces/ghc- stage2" -dcore-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn- missed-specialisations -fshow-warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -dno-debug-output --interactive -v0 -ignore- dot-ghci -fno-ghci-history +RTS -I0.1 -RTS -ignore-dot-ghci< break027.script Actual stdout output differs from expected: diff -uw "./ghci.debugger/scripts/break027.run/break027.stdout.normalised" "./ghci.debugger/scripts/break027.run/break027.run.stdout.normalised" --- ./ghci.debugger/scripts/break027.run/break027.stdout.normalised 2017-02-08 15:52:10.750125249 -0500 +++ ./ghci.debugger/scripts/break027.run/break027.run.stdout.normalised 2017-02-08 15:52:10.750125249 -0500 @@ -1,8 +1,8 @@ Breakpoint 0 activated at QSort.hs:4:12-13 Breakpoint 1 activated at QSort.hs:5:16-51 Stopped in QSort.qsort, QSort.hs:5:16-51 -_result :: [Integer] = _ -a :: Integer = 3 -left :: [Integer] = _ -right :: [Integer] = _ -a :: Integer -- Defined in ‘interactive:Ghci1’ +_result :: [a] = _ +a :: a = _ +left :: [a] = _ +right :: [a] = _ +a :: a -- Defined in ‘interactive:Ghci1’ *** unexpected failure for break027(ghci) =====> print001(ghci) 11 of 101 [0, 7, 0] cd "./ghci.debugger/scripts/print001.run" && HC="/mnt/work/ghc/ghc- testing/inplace/test spaces/ghc-stage2" HC_OPTS="-dcore-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn-missed-specialisations -fshow- warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -dno- debug-output " "/mnt/work/ghc/ghc-testing/inplace/test spaces/ghc- stage2" -dcore-lint -dcmm-lint -no-user-package-db -rtsopts -fno-warn- missed-specialisations -fshow-warning-groups -fdiagnostics-color=never -fno-diagnostics-show-caret -dno-debug-output --interactive -v0 -ignore- dot-ghci -fno-ghci-history +RTS -I0.1 -RTS -ignore-dot-ghci< print001.script Actual stdout output differs from expected: diff -uw "./ghci.debugger/scripts/print001.run/print001.stdout.normalised" "./ghci.debugger/scripts/print001.run/print001.run.stdout.normalised" --- ./ghci.debugger/scripts/print001.run/print001.stdout.normalised 2017-02-08 15:51:08.413033889 -0500 +++ ./ghci.debugger/scripts/print001.run/print001.run.stdout.normalised 2017-02-08 15:51:08.413033889 -0500 @@ -1,10 +1,9 @@ li = (_t1::[Maybe Integer]) Just 0 -li = Just 0 : (_t2::[Maybe Integer]) +li = (_t2::[Maybe Integer]) 6 -li = [Just 0,(_t3::Maybe Integer),(_t4::Maybe Integer), - (_t5::Maybe Integer),(_t6::Maybe Integer),(_t7::Maybe Integer)] -li = [Just 0,_,_,_,_,_] +li = (_t3::[Maybe Integer]) +li = _ [Just 0,Just 1,Just 2,Just 3,Just 4,Just 5] -li = [Just 0,Just 1,Just 2,Just 3,Just 4,Just 5] -li = [Just 0,Just 1,Just 2,Just 3,Just 4,Just 5] +li = (_t4::[Maybe Integer]) +li = _ *** unexpected failure for print001(ghci) }}} It would be nice to know what is going on here. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13243> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8414: ghc-pkg prevents dynamic library only packages
by GHC 04 Sep '18

04 Sep '18

#8414: ghc-pkg prevents dynamic library only packages ------------------------------------+------------------------------------- Reporter: AndreasVoellmy | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: ghc-pkg | Version: Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- GHC supports compiling Haskell libraries as dynamic libraries and building executables against dynamic libraries. GHCi seems to support loading modules from dynamic libraries, too. So it would seem that it should be possible to have packages that only include dynamic libraries, omitting the .a and .o files typically generated. cabal-install allows building dynamic libraries only, for example with the command "cabal install --disable-library-vanilla --enable-shared --disable-library-profiling". However, ghc-pkg register refuses to install the package without the .a files present. This seems to be a bug with ghc-pkg. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8414> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10374: Can't build GHC with a dynamic only GHC installation
by GHC 04 Sep '18

04 Sep '18

#10374: Can't build GHC with a dynamic only GHC installation -------------------------------------+------------------------------------- Reporter: jessicah | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build | Version: 7.10.1 System | Operating System: Unknown/Multiple Keywords: | Type of failure: Building GHC Architecture: | failed Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- When an installation of GHC doesn't include the vanilla "way", GHC cannot be built from this existing installation of GHC. E.g. using the following mk/build.mk: {{{ V = 0 GhcLibWays = dyn SRC_HC_OPTS = -O -H64m GhcStage1HcOpts = -O -fasm GhcStage2HcOpts = -O2 -fasm GhcHcOpts = -Rghc-timing GhcLibHcOpts = -O2 DYNAMIC_BY_DEFAULT = YES NoFibWays = STRIP_CMD = : }}} Steps to reproduce: 1. build & install GHC using above configuration 2. rebuild GHC using above configuration, --with-ghc pointing to the installation created in step 1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10374> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14963: ghci -fdefer-type-errors can't run IO action from another module
by GHC 04 Sep '18

04 Sep '18

#14963: ghci -fdefer-type-errors can't run IO action from another module -------------------------------------+------------------------------------- Reporter: elaforge | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.4.1 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: -------------------------------------+------------------------------------- This is enough to trigger a crash on OS X and Linux: Bug1.hs: {{{ module Bug1.hs where import qualified Bug2 test :: IO Bool test = Bug2.failure }}} Bug2.hs: {{{ module Bug2 where failure :: IO Bool failure = return False }}} Shell: {{{ % ghci -fdefer-type-errors -ignore-dot-ghci GHCi, version 8.4.1: http://www.haskell.org/ghc/ :? for help Prelude> :load Bug [1 of 2] Compiling Bug2 ( Bug2.hs, interpreted ) [2 of 2] Compiling Bug ( Bug.hs, interpreted ) Ok, two modules loaded. *Bug> test ghc: panic! (the 'impossible' happened) (GHC version 8.4.1 for x86_64-apple-darwin): nameModule system $dShow_a1LX Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} This is specific to 8.4.1, in 8.0.2 I get "False" as expected. If I leave off -fdefer-type-errors, it works. It also seems to be ghci only, compiling with -fdefer-type-errors doesn't have the problem. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14963> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14589: The isUpper function should return true for the '\9438' character
by GHC 03 Sep '18

03 Sep '18

#14589: The isUpper function should return true for the '\9438' character -------------------------------------+------------------------------------- Reporter: mrkkrp | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 8.2.1 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: -------------------------------------+------------------------------------- {{{ λ> toLower '\9438' '\9438' λ> toUpper '\9438' '\9412' λ> isUpper '\9438' False λ> isLower '\9438' False }}} Here we can observe a contradiction. The `toLower` function does not alter its argument, but `toUpper` does, which tells us that the character 1) has the notion of case 2) it must be lower-cased. On the other hand, both `isUpper` and `isLower` functions return `False` for `\9438` suggesting that it has no notion of case. Apparently, `\9438` is lower-cased and `\9412` is its upper-cased version indeed: {{{ λ> putStrLn "\9438" ⓞ λ> putStrLn "\9412" Ⓞ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14589> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8441: Allow family instances in an hs-boot file
by GHC 03 Sep '18

03 Sep '18

#8441: Allow family instances in an hs-boot file ------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Compiling an .hs-boot file with a data instance leads to this error: {{{ Illegal family instance in hs-boot file }}} Yet, data instances make good sense in an hs-boot file, in case another module wants to access a constructor declared in the instance. Furthermore, it may sometimes be desirable to allow type family instances in a hs-boot file, as well, in case some including modules need the instance for type simplification. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8441> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13930: Cabal configure
by GHC 02 Sep '18

02 Sep '18

#13930: Cabal configure -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 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: -------------------------------------+------------------------------------- `cabal configure` apparently has a space leak when compiled with GHC HEAD but not 8.0. It's not clear whether this is really a GHC regression yet, but here it is certainly GHC version-specific. See https://github.com/haskell/cabal/issues/4589 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13930> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15575: Investigate Haskell rewrite of testsuite driver
by GHC 02 Sep '18

02 Sep '18

#15575: Investigate Haskell rewrite of testsuite driver -------------------------------------+------------------------------------- Reporter: tdammers | Owner: (none) Type: task | Status: new Priority: normal | Milestone: Research needed Component: Test Suite | Version: 8.4.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #15363 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently, the testsuite driver is written in Python. This is a bit of a liability: - Having to program in "not Haskell" might scare away potential contributors here - Even developers who are proficient in Python probably prefer working with Haskell - Managing Python as a dependency poses an additional burden and complicates deployment, setting up dev environments, CI, etc.; especially on Windows. - We miss out on the benefits of type checks and typed programming for a substantial bit of infrastructure - We miss out on a nice dog-fooding opportunity So in order to judge the scope of this task, and define it better, it would be good to investigate a bit: - What would it take to get high-level feature parity with the current solution? - Does the Haskell ecosystem cover the concerns that we would like to address with existing libraries? (Process management, for example) - Can we come up with a smart and frictionless way of migrating all the existing test cases in a reliable automated fashion? - What are risks and unknowns? #15363 is the recent case that sparked this - rather than the proposed patch there, which ports existing Haskell code to Python, we would prefer going in the other direction. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15575> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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