May 2014 - ghc-tickets

[GHC] #8325: Pattern guards in anonymous functions
by GHC 25 Jan '16

25 Jan '16

#8325: Pattern guards in anonymous functions ------------------------------------+------------------------------------- Reporter: mcollis | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- In the course of a project, I had an idea that would allow less cumbersome use of cases in anonymous functions. Here's a simple example of what I'm proposing: {{{ (\x y | x > y -> x | otherwise -> something else) }}} Currently, the only way to accomplish this is with if() then ... else syntax or the use of the MultiWayIf and LambdaCase extensions. The syntax I've proposed here matches with existing anonymous function syntax and doesn't conflict with any other GHC syntax. This would greatly improve the readability of complex anonymous functions. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8325> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8572: Building an empty module with profiling requires profiling libraries for integer-gmp
by GHC 24 Jan '16

24 Jan '16

#8572: Building an empty module with profiling requires profiling libraries for integer-gmp -------------------------------------------+------------------------------- Reporter: parcs | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.7 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- {{{ #!haskell {-# LANGUAGE NoImplicitPrelude #-} module A where }}} {{{ $ ghc-stage2 -prof -c A.hs Top level: Failed to load interface for ‛GHC.Integer.Type’ Perhaps you haven't installed the profiling libraries for package ‛integer-gmp’? Use -v to see a list of the files searched for. }}} I can't built module `A` without profiling libraries for `integer-gmp`, even though I don't use `integer-gmp` anywhere in the module. This happens because the `Tidy Core` pass attempts to look up the `mkInteger` name (in order to desugar integer literals) even when there are no integer literals in the module. The obvious fix is to lazily look up `mkInteger` in `Coreprep.lookupMkIntegerName`: {{{ #!diff diff --git a/compiler/coreSyn/CorePrep.lhs b/compiler/coreSyn/CorePrep.lhs index 5e0cd65..9836982 100644 --- a/compiler/coreSyn/CorePrep.lhs +++ b/compiler/coreSyn/CorePrep.lhs @@ -56,6 +56,7 @@ import Config import Data.Bits import Data.List ( mapAccumL ) import Control.Monad +import System.IO.Unsafe ( unsafeInterleaveIO ) \end{code} -- --------------------------------------------------------------------------- @@ -1119,6 +1120,7 @@ lookupMkIntegerName dflags hsc_env else if thisPackage dflags == integerPackageId then return $ panic "Can't use Integer in integer" else liftM tyThingId + $ unsafeInterleaveIO $ initTcForLookup hsc_env (tcLookupGlobal mkIntegerName) mkInitialCorePrepEnv :: DynFlags -> HscEnv -> IO CorePrepEnv }}} This way, we don't attempt to look up `mkInteger` until we actually need it, i.e. if there are integer literals that we must desugar. Relevant commits are 2ef5cd26db27543ac8664a3d18f45550d0109a8b and fdd552e0ecaa17300670a48562995040e1d6687e -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8572> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8285: unexpected behavior with encodeFloat on large inputs
by GHC 23 Jan '16

23 Jan '16

#8285: unexpected behavior with encodeFloat on large inputs --------------------------+------------------------------------------------ Reporter: carter | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: | Version: 7.7 Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: Incorrect result at runtime Architecture: | Test Case: Unknown/Multiple | Blocking: Difficulty: | Unknown | Blocked By: | Related Tickets: | --------------------------+------------------------------------------------ benjamin scarlet discovered some unexpected behavior in encodeFloat today {{{ <bscarlet> > map (\x -> encodeFloat 1 (shiftL 1 x)) [30,31] [23:47:47] <lambdabot> [Infinity,0.0] [23:49:09] <arkeet> > encodeFloat 1 60 [23:49:10] <lambdabot> 1.152921504606847e18 [23:49:09] <arkeet> > encodeFloat 1 60 [23:49:10] <lambdabot> 1.152921504606847e18 [23:49:18] <arkeet> er. [23:50:21] <bscarlet> down in the sane range I suspect it's just fine. [23:50:43] <bscarlet> > encodeFloat 1 1000 [23:50:44] <lambdabot> 1.0715086071862673e301 [23:50:52] <bscarlet> > encodeFloat 1 10000 [23:50:53] <lambdabot> Infinity [23:50:58] <bscarlet> That's sane. [23:51:03] <arkeet> > encodeFloat 1 (2^31) [23:51:04] <lambdabot> 0.0 [23:51:13] <bscarlet> That's what I think is weird. [23:51:19] <carter> bscarlet floats are weird [23:51:23] <arkeet> > encodeFloat 1 (2^31-1) [23:51:24] <lambdabot> Infinity }}} Benjamin did a wee bit of investigation, and the problem seems to lie in https://github.com/ghc/packages-integer- gmp/blob/master/cbits/float.c#L177 in integer-gmp, where it deliberately doesn't handle the edge cases (probably worth investigating) if integer-simple has similar behavior or not -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8285> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8403: Pretty-printing of long types
by GHC 23 Jan '16

23 Jan '16

#8403: Pretty-printing of long types ------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Low priority, but this ghci output could be more packed. {{{ λ> :t (,,,,,,,,,,,,,,,,,,,,,,,) (,,,,,,,,,,,,,,,,,,,,,,,) :: a -> b -> c -> d -> e -> f -> g -> h -> i -> j -> k -> l -> m -> n -> o -> p -> q -> r -> s -> t -> u -> v -> w -> x -> (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8403> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8064: Warning out when "undefined" value has been used.
by GHC 23 Jan '16

23 Jan '16

#8064: Warning out when "undefined" value has been used. ------------------------------------+------------------------------------- Reporter: freizl | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Programmer may like to use "undefined" to define a function or value, which usually means "later implementation". However, people might forget to implement it thus cause run time error. Wish GHC will show some warning/errors at compilation. This idea comes from this article (http://www.devalot.com/articles/2013/07 /why-haskell.html) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8064> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8422: type nats solver is too weak!
by GHC 23 Jan '16

23 Jan '16

#8422: type nats solver is too weak! -------------------------------------+------------------------------------- Reporter: carter | Owner: Type: bug | Status: new Priority: highest | Milestone: 7.8.1 Component: Compiler (Type | Version: 7.7 checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: GHC rejects Architecture: Unknown/Multiple | valid program Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- I just built ghc HEAD today, and the type nat solver can't handle the attached program, which *should* be simple to check! (and while I could use unsafeCoerce to "prove" it correct, that defeats the purpose of having the type nat solver!) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8422> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8618: can't load .so/.DLL
by GHC 22 Jan '16

22 Jan '16

#8618: can't load .so/.DLL -----------------------------------+--------------------------------------- Reporter: Feuerbach | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (NCG) | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- This happens in a fresh sandbox: {{{ % cabal install uniplate -j Resolving dependencies... Configuring syb-0.4.1... Configuring text-1.0.0.0... Building syb-0.4.1... Building text-1.0.0.0... Installed syb-0.4.1 Installed text-1.0.0.0 Configuring hashable-1.2.1.0... Building hashable-1.2.1.0... Installed hashable-1.2.1.0 Configuring unordered-containers-0.2.3.3... Building unordered-containers-0.2.3.3... Installed unordered-containers-0.2.3.3 Configuring uniplate-1.6.12... Building uniplate-1.6.12... Failed to install uniplate-1.6.12 Last 10 lines of the build log ( /home/feuerbach/.cabal/logs/uniplate-1.6.12.log ): Preprocessing library uniplate-1.6.12... [ 1 of 21] Compiling Data.Generics.Uniplate.Data.Instances ( Data/Generics/Uniplate/Data/Instances.hs, dist/build/Data/Generics/Uniplate/Data/Instances.o ) [ 2 of 21] Compiling Data.Generics.Uniplate.Internal.Utils ( Data/Generics/Uniplate/Internal/Utils.hs, dist/build/Data/Generics/Uniplate/Internal/Utils.o ) Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package bytestring-0.10.4.0 ... linking ... done. Loading package text-1.0.0.0 ... <command line>: can't load .so/.DLL for: libHStext-1.0.0.0.so (libHStext-1.0.0.0.so: cannot open shared object file: No such file or directory) cabal: Error: some packages failed to install: uniplate-1.6.12 failed during the building phase. The exception was: ExitFailure 1 }}} I have shared: False in cabal.config, so it's not surprising that libHStext-1.0.0.0.so is not found. What is surprising is that it's needed. uniplate doesn't use TemplateHaskell, from what I can tell. This is GHC 7.7.20131217. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8618> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8586: internal error: evacuate(static): strange closure type 5189
by GHC 22 Jan '16

22 Jan '16

#8586: internal error: evacuate(static): strange closure type 5189 ----------------------------+------------------------------- Reporter: guest | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: crash | Operating System: Windows Architecture: x86 | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+------------------------------- I cannot reproduce this reliably, but it happened once. Here’s what I did: * Install Yesod * Scaffold a blank Yesod project with no DB * Run GHCi * :l Foundation.hs * :info AForm Output: {{{ newtype AForm m a = AForm {unAForm :: (HandlerSite m, [Text]) -> Maybe (Env, FileEnv) -> Ints -> m (FormResult a, [FieldView (HandlerSite m)] -> [FieldView (HandlerSite m)], Ints, Enctype)} -- Defined in `Yesod.Form.Types' instance Monad m => Functor (AForm m) -- Defined in `Yesod.Form.Types' instance (Monad m, Monoid a) => Monoid (AForm m a) -- Defined in `Yesod.Form.Types' instance MonadTransghc.exe: internal error: evacuate(static): strange closure type 5189 (GHC version 7.6.3 for i386_unknown_mingw32) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. }}} (P.S. I chose 'x86' for the Architecture because it’s running as 32-bit, but I’m actually using 64-bit Windows.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8586> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8605: Alternative, guard-like syntax for view patterns
by GHC 22 Jan '16

22 Jan '16

#8605: Alternative, guard-like syntax for view patterns ------------------------------------+------------------------------------- Reporter: cactus | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Implement the alternative syntax for view patterns described on the ViewPatternsAlternative wiki page -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8605> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8907: Un-zonked kind variable passes through type checker
by GHC 22 Jan '16

22 Jan '16

#8907: Un-zonked kind variable passes through type checker -------------------------------------------+------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.8.1-rc2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- I have this module: {{{ {-# LANGUAGE PolyKinds #-} module Bug where data Poly a }}} Now, I say this: {{{ > ghc Bug.hs -fforce-recomp -dppr-debug -fprint-explicit-foralls -ddump-tc }}} The following is produced: {{{ [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) TYPE SIGNATURES TYPE CONSTRUCTORS main:Bug.Poly{tc rn2} :: k{tv ao6} [sk] -> ghc-prim:GHC.Prim.*{(w) tc 34d} data Poly{tc} (k::ghc-prim:GHC.Prim.BOX{(w) tc 347}) (a::k) No C type associated Roles: [nominal, phantom] RecFlag NonRecursive, Not promotable = FamilyInstance: none COERCION AXIOMS Dependent modules: [] Dependent packages: [base, ghc-prim, integer-gmp] ==================== Typechecker ==================== }}} My concern is the `[sk]` that appears after the kind variable `k_ao6`. It would appear that a ''skolem'' type variable passes out of the type- checker and is used as the binder for polymorphic kind of `Poly`. Should this get zonked somewhere? My guess is that there is no way to get this apparent misbehavior to trigger some real failure, given that the variable will be substituted away before much else happens. Yet, when I saw a skolem appear in a similar position after modifying the type-checker, I was sure I had done something wrong somewhere. So, is this intended or accidental behavior? If accidental, should we be scared? If we needn't be scared, I'm happy to close this as wontfix, but a Note would probably be helpful somewhere. Apologies if that Note is already written and I missed it! The same behavior is present in 7.8.1 RC 2 and in HEAD. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8907> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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