May 2015 - ghc-tickets

[GHC] #9230: Make -fwarn-tabs the default
by GHC 31 Jul '15

31 Jul '15

#9230: Make -fwarn-tabs the default -------------------------------------------+------------------------------- Reporter: dfeuer | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Easy (less than 1 hour) | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: -------------------------------------------+------------------------------- Tabs trip up an awful lot of Haskell beginners. Turning the warning on by default will likely save them a lot of grief. Any insane^h^h^h^h^h^hexperienced Haskellers who like tabs will have no trouble disabling the warning in their pragmas. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9230> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9070: "Simplifier ticks exhausted"
by GHC 31 Jul '15

31 Jul '15

#9070: "Simplifier ticks exhausted" ----------------------------------+------------------------------------- Reporter: dermesser | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: x86_64 (amd64) | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------------- I know nothing more than what GHC said (I'm on debian, installed from the repositories). {{{ (GHC version 7.6.3 for x86_64-unknown-linux): Simplifier ticks exhausted When trying UnfoldingDone base:GHC.Base.$fMonadIO_$c>>={v rJ2} [gid] To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed To see detailed counts use -ddump-simpl-stats Total ticks: 31764 }}} The code triggering the error is the code commented out in lines 52-54: {{{ 42 redis_family_raw <- getEnv redisFamilyVar 43 redis_addr <- getEnv redisAddressVar 44 redis_port <- getEnv redisPortVar 45 46 (family,redis_family) <- case (parseFamily family_raw,parseFamily redis_family_raw) of 47 (Just fam, Just rfam) -> return (fam,rfam) 48 x -> fail $ "Unknown address family: " ++ show x 49 50 sockaddr <- getSockAddr family broker_address broker_port_raw 51 52 --redis_conn <- case redis_family of 53 -- WAFamilyInet -> R.connect $ defaultConnectInfo { connectHost = redis_addr, connectPort = Service redis_port } 54 -- WAFamilyUnix -> R.connect $ defaultConnectInfo { connectPort = UnixSocket redis_addr } }}} However, this bug occurs only when compiling with cabal. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9070> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9227: Coverage Condition cannot be turned off
by GHC 31 Jul '15

31 Jul '15

#9227: Coverage Condition cannot be turned off ------------------------------------+------------------------------------- Reporter: augustss | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Compile this program {{{ {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-} module Bug1 where class C a b | a -> b data A a = A data B a = B instance C (A a) (B b) }}} and observe the error message {{{ Bug1.hs:9:10: Illegal instance declaration for `C (A a) (B b)' The coverage condition fails in class `C' for functional dependency: `a -> b' Reason: lhs type `A a' does not determine rhs type `B b' In the instance declaration for `C (A a) (B b)' }}} Then read manual, sec 7.6.3.3: {{{ Both the Paterson Conditions and the Coverage Condition are lifted if you give the -XUndecidableInstances flag }}} Compile again with -XUndecidableInstances. Observe the exact same error message. Either the compiler or the documentation is wrong. I certainly hope it is the compiler, because it worked in 7.6 and was quite useful. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9227> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8253: example "Core syntax" is ancient
by GHC 31 Jul '15

31 Jul '15

#8253: example "Core syntax" is ancient -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Documentation | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Documentation Difficulty: Easy (less than 1 | bug hour) | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- [http://www.haskell.org/ghc/docs/7.6.3/html/users_guide/options- debugging.html#idp39365504 User's guide section 4.19.5] has some funky "Core syntax" that (according to git blame) dates back to at least 2000, and probably longer ago than that. It could use an update. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8253> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8151: ghc-7.4.2 on OpenIndiana (Solaris) createSubprocess fails
by GHC 31 Jul '15

31 Jul '15

#8151: ghc-7.4.2 on OpenIndiana (Solaris) createSubprocess fails ----------------------------+-------------------------------------------- Reporter: troydm | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.4.2 Keywords: | Operating System: Solaris Architecture: x86 | Type of failure: Runtime performance bug Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+-------------------------------------------- when i'm compiling this test.hs with ghc -thread ./test.hs and then execute it i get Starting Subprocess Exit code: ExitFailure 127 This error code indicates that command isn't found (i have ghc in /usr/local/bin) and it's specified in PATH variable, however it acts as if it's not even there however if i remove -threaded flag and recompile code again, it works Starting Subprocess ghc: no input files Usage: For basic information, try the `--help' option. Exit code: ExitFailure 1 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8151> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10467: user's guide description of "foreign export" is out of date
by GHC 31 Jul '15

31 Jul '15

#10467: user's guide description of "foreign export" is out of date -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.1 Documentation | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The first sentence of section 8.2.1 is > When GHC compiles a module (say M.hs) which uses foreign export or foreign import "wrapper", it generates two additional files, M_stub.c and M_stub.h. GHC will automatically compile M_stub.c to generate M_stub.o at the same time. This is false at least for registerised builds, GHC produces an object file directly and its filename is `M.o` not `M_stub.o`. (I don't know what happens in the unregisterised case, but if the final object file name is actually different, that seems inconsistent.) The rest of the section makes similar references to the nonexistent `M_stub.c` and `M_stub.o`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10467> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9114: Invalid UTF8 not round-tripped correctly
by GHC 31 Jul '15

31 Jul '15

#9114: Invalid UTF8 not round-tripped correctly ------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: libraries/base | 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: | ------------------------------------+------------------------------------- As reported by Robert Bihlmeyer at http://bugs.debian.org/748125, the promised round-tripping of invalid UTF8 sequences in filenames through String does not work: ``` $ mkdir foo $ touch foo/$(echo -e '\xC0\xB7.txt') $ ghc -e 'System.Directory.getDirectoryContents "foo" >>= print . last' "7.txt" ``` The sequence 0xC8B7 is an (invalid) encoding of 37, i.e. `'7'`, so if it is mapped to `'7'`, no round-tripping is possible. (Other invalid byte sequences are round-tripped.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9114> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9385: Additions to Control.Monad
by GHC 31 Jul '15

31 Jul '15

#9385: Additions to Control.Monad -------------------------------------+------------------------------------- Reporter: olf | Owner: Type: feature request | Status: new Priority: low | Milestone: Component: libraries/base | Version: 7.8.2 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'd like to propose the following additions/changes to Control.Monad: `mfilter` can be generalised: {{{#!hs gen_mfilter :: Monad m => (a -> m ()) -> m a -> m a gen_mfilter f ma = (\a -> liftM (const a) (f a)) =<< ma }}} Now we obtain the old `mfilter` as {{{#!hs gen_mfilter.(guard.) }}} Further, `m ()` is a monoid for every monad, which would cause conflicts for `[()]`, to name one example. (The usual monoid instance of `[()]` is addition of natural numbers, while the monadic monoid instance is multiplication.) More generally, the monoid `m ()` acts on every type `m a` in the following way: {{{#!hs mtimes :: Monad m => m () -> m a -> m a mtimes = gen_mfilter.const = liftM2 (flip const) when = mtimes.guard }}} For example, each element of a list can be duplicated like this: {{{#!hs mtimes [(),()] }}} To see why these functions are useful, consider the `DDist` monad of the ProbabilityMonads package: Since `DDist ()` is essentially the monoid of real numbers with multiplication, `gen_mfilter f` updates a distribution by multiplying the weight of `x` by `f x`. Another example is the state monad `ST s`, where type `(a -> ST s ())` is essentially `a -> s -> s`, so these functions encode changes that, when used with `gen_mfilter` alter state, not the value. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9385> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9260: Unnecessary error using GHC.TypeLits
by GHC 30 Jul '15

30 Jul '15

#9260: Unnecessary error using GHC.TypeLits -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 7.8.2 Keywords: type lits, data | Operating System: Linux kinds, error message | Type of failure: Incorrect Architecture: Unknown/Multiple | warning at compile-time Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | -------------------------------------+------------------------------------- Compiling: {{{ {-# LANGUAGE DataKinds, TypeOperators, GADTs #-} module Error where import GHC.TypeLits data Fin n where Fzero :: Fin (n + 1) Fsucc :: Fin n -> Fin (n + 1) }}} gives a strange (unnecessary) error message claiming that `Fin 1` doesn't match the expected type `Fin (0 + 1)`: {{{ % ghc --version The Glorious Glasgow Haskell Compilation System, version 7.8.2 % ghc -ignore-dot-ghci /tmp/Error.hs [1 of 1] Compiling Error ( /tmp/Error.hs, /tmp/Error.o ) /tmp/Error.hs:12:8: Couldn't match type ‘0’ with ‘1’ Expected type: Fin 1 Actual type: Fin (0 + 1) In the expression: Fsucc Fzero In an equation for ‘test’: test = Fsucc Fzero /tmp/Error.hs:12:14: Couldn't match type ‘1’ with ‘0’ Expected type: Fin 0 Actual type: Fin (0 + 1) In the first argument of ‘Fsucc’, namely ‘Fzero’ In the expression: Fsucc Fzero % }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9260> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9772: Building documentation alone is broken
by GHC 30 Jul '15

30 Jul '15

#9772: Building documentation alone is broken -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Build System | Version: 7.9 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Building Blocked By: | GHC failed Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- At the moment it seems that the only way to build documentation is to actually build all of GHC, which is nonsense. Methods of building documentation described in Building/Docs are broken: {{{ To build just the Haddock docs for a given library, do this: cd libraries/base make html stage=0 FAST=YES }}} That ends with errors. See `haddock_for_lib.log` attachement. {{{ To build a document on its own, for example the Users Guide, do this: cd docs/users_guide make html stage=0 FAST=YES substitute 'html' for 'pdf' or 'ps' to build other types of documentation. }}} That also ends with errors. See `users_guide.log` attachement. For above experiments I used the following lines in my `mk/build.mk` file: {{{ HADDOCK_DOCS = YES BUILD_DOCBOOK_HTML = YES BUILD_DOCBOOK_PS = NO BUILD_DOCBOOK_PDF = NO }}} Then I run `perl boot && ./configure`. I didn't run `make`, just the above instructions. My configure returns this: {{{ Configure completed successfully. Building GHC version : 7.9.20141105 Build platform : x86_64-unknown-linux Host platform : x86_64-unknown-linux Target platform : x86_64-unknown-linux Bootstrapping using : /home/killy/.ghc-sandbox/bin/ghc which is version : 7.8.3 Using gcc : /usr/bin/gcc which is version : 4.5.1 Building a cross compiler : NO cpp : /usr/bin/gcc cpp-flags : -E -undef -traditional ld : /usr/bin/ld Happy : /home/killy/.cabal/bin/happy (1.19.4) Alex : /home/killy/.cabal/bin/alex (3.1.3) Perl : /usr/bin/perl dblatex : /usr/bin/dblatex xsltproc : /usr/bin/xsltproc Using LLVM tools llc : /usr/bin/llc opt : /usr/bin/opt HsColour : /home/killy/.cabal/bin/HsColour Building DocBook HTML documentation : NO Building DocBook PS documentation : YES Building DocBook PDF documentation : YES }}} I'm setting the milestone to 7.10.1. It's annoying to have this feature of the build system broken and it would be great to have this fixed. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9772> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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