August 2015 - ghc-tickets

[GHC] #10674: Expose OSThreadID and assorted functions from Haskell
by GHC 24 Sep '15

24 Sep '15

#10674: Expose OSThreadID and assorted functions from Haskell -------------------------------------+------------------------------------- Reporter: Fuuzetsu | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Currently given two {{{ThreadId}}}s, there is no way to tell without FFI if they are running on the same OS thread. There is not even a way to ask what OS thread we are currently on: something like {{{myThreadId}}} except {{{myOsThreadId}}}. Currently to remedy this, the user has to effectively copy and paste parts of the internal rts files and use something like {{{.hsc}}} with CPP to get at this information. This is not really portable on the user side and requires nasty gutting. In the RTS the function we are interested in is at least {{{osThreadId}}}: at least with this function we can inspect current {{{OSThreadId}}} and communicate it out through an {{{MVar}}} or otherwise. So this is a feature request for an abstract type {{{OSThreadId}}} with instances of at least {{{Eq, Show}}} and a function {{{myOsThreadId :: IO OSThreadId}}}. Nice to have would be {{{osThreadId :: ThreadID -> IO OSThreadId}}} but not critical. If there is room for optimisation in GHC, functions like {{{sameOsThread :: ThreadId -> ThreadId -> IO Bool}}} would also be nice but again not critical. Not sure what to set in ticket meta-data so please change as appropriate. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10674> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10692: Replace (SourceText, FastString) with WithSourceText data type
by GHC 24 Sep '15

24 Sep '15

#10692: Replace (SourceText,FastString) with WithSourceText data type -------------------------------------+------------------------------------- Reporter: alanz | Owner: alanz Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Phab:D907 introduced `SourceText` for a number of data types, by replacing `FastString` with `(SourceText,FastString)`. Since this has an `Outputable` instance, no warnings are generated when `ppr` is called on it, but unexpected output is generated. See Phab:D1096 for an example of this. Replace the `(SourceText,FastString)` tuples with a new data type {{{#!hs data WithSourceText = WithSourceText SourceText FastString }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10692> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10767: SPECIALIZE generates warning but works fine
by GHC 24 Sep '15

24 Sep '15

#10767: SPECIALIZE generates warning but works fine -------------------------------------+------------------------------------- Reporter: osa1 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- I have this code: {{{#!hs {-# LANGUAGE ScopedTypeVariables, TypeFamilies #-} module Main where import Data.Proxy class SpecList a where type List a :: * slCase :: List a -> b -> (a -> List a -> b) -> b data IntList = ILNil | ILCons {-# UNPACK #-} !Int IntList deriving (Show) instance SpecList Int where type List Int = IntList slCase ILNil n _ = n slCase (ILCons i t) _ c = c i t fromList :: [Int] -> IntList fromList [] = ILNil fromList (h : t) = ILCons h (fromList t) lst1 :: IntList lst1 = fromList [1..10] {-# SPECIALIZE genLength :: Proxy Int -> List Int -> Int #-} genLength :: forall a . SpecList a => Proxy a -> List a -> Int genLength p lst = slCase lst 0 (\(_ :: a) tail -> 1 + genLength p tail) main :: IO () main = print (genLength (Proxy :: Proxy Int) lst1) }}} When I compile it(no matter which optimization level is used), it prints this warning: {{{ Main.hs:30:1: Warning: RULE left-hand side too complicated to desugar Optimised lhs: case cobox_a17r of _ [Occ=Dead] { GHC.Types.Eq# cobox -> genLength @ Int $dSpecList_a17q } Orig lhs: case cobox_a17r of cobox_a17r { GHC.Types.Eq# cobox -> genLength @ Int $dSpecList_a17q } }}} (I presume this is related with the rewrite rule generated to be able to replace calls to generic version to calls to specialized versions when possible.) But this program compiles fine with -O2, i.e. `genLength lst1` is replaced with specialized definition of `genLength`, without any dictionary passing. So the warning is confusing for two reasons: - It's not related with the code, it seems like it's a problem with GHC- generated rewrite rule. - It still works fine. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10767> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10738: Make Exception datatypes into newtypes
by GHC 24 Sep '15

24 Sep '15

#10738: Make Exception datatypes into newtypes -------------------------------------+------------------------------------- Reporter: | Owner: RyanGlScott | Type: feature | Status: new request | Priority: normal | Milestone: Component: | Version: 7.10.2 libraries/base | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #4961 Differential Revisions: | -------------------------------------+------------------------------------- Certain instances of `Exception` in `base` are datatypes with only one argument: {{{#!hs data RecUpdError = RecUpdError String data RecConError = RecConError String data RecSelError = RecSelError String data PatternMatchFail = PatternMatchFail String data NoMethodError = NoMethodError String data AssertionFailed = AssertionFailed String }}} Why not make these into `newtype`s? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10738> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10555: RULE left-hand side too complicated to desugar
by GHC 24 Sep '15

24 Sep '15

#10555: RULE left-hand side too complicated to desugar -------------------------------------+------------------------------------- Reporter: yongqli | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2-rc1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: yes | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- GHC version 7.10.1.20150612 breaks the `fast-math` package, which compiled fine on GHC 7.10.1. To reproduce, run `cabal install fast-math`. {{{ Numeric/FastMath/Approximation.hs:60:1: Warning: RULE left-hand side too complicated to desugar Optimised lhs: case /## y2 x of wild_00 { __DEFAULT -> (case /## y1 x of wild_X2 { __DEFAULT -> +## wild_X2 }) wild_00 } Orig lhs: case /## y2 x of wild_00 { __DEFAULT -> (case /## y1 x of wild_00 { __DEFAULT -> +## wild_00 }) wild_00 } Numeric/FastMath/Approximation.hs:63:1: Warning: RULE left-hand side too complicated to desugar Optimised lhs: case /## y2 x of wild_00 { __DEFAULT -> (case /## y1 x of wild_X2 { __DEFAULT -> -## wild_X2 }) wild_00 } Orig lhs: case /## y2 x of wild_00 { __DEFAULT -> (case /## y1 x of wild_00 { __DEFAULT -> -## wild_00 }) wild_00 } Numeric/FastMath/Approximation.hs:103:1: Warning: RULE left-hand side too complicated to desugar Optimised lhs: case divideFloat# y2 x of wild_00 { __DEFAULT -> (case divideFloat# y1 x of wild_X2 { __DEFAULT -> minusFloat# wild_X2 }) wild_00 } Orig lhs: case divideFloat# y2 x of wild_00 { __DEFAULT -> (case divideFloat# y1 x of wild_00 { __DEFAULT -> minusFloat# wild_00 }) wild_00 } ghc: panic! (the 'impossible' happened) (GHC version 7.10.1.20150612 for x86_64-unknown-linux): Simplifier ticks exhausted When trying RuleFired float commute left * 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: 4004 Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10555> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8832: Constant-folding regression wrt `clearBit (bit 0) 0 `
by GHC 24 Sep '15

24 Sep '15

#8832: Constant-folding regression wrt `clearBit (bit 0) 0 ` ------------------------------+-------------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.8.1 Component: Compiler | Version: 7.8.1-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime performance bug Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | ------------------------------+-------------------------------------------- While implementing `zeroBits` (see [83bd2f5fc7e/base]) I noticed that constant folding of the expression `clearBit (bit 0) 0` regressed (and improved at the same time) from GHC 7.6.3 to GHC 7.8.1, specifically, the following module {{{#!haskell {-# LANGUAGE CPP #-} module M where import Data.Bits import Data.Int import Data.Word #define T(s,T) \ s :: T ; \ s = clearBit (bit 0) 0 ; \ T(i,Int) T(i8,Int8) T(i16,Int16) T(i32,Int32) T(i64,Int64) T(w,Word) T(w8,Word8) T(w16,Word16) T(w32,Word32) T(w64,Word64) T(z,Integer) }}} compiled with GHC 7.8.1RC2 results in the following Core output: {{{#!haskell -- GHC 7.8.1RC2 i = I# (andI# 1 (notI# 1)) i8 = I8# 0 i16 = I16# 0 i32 = I32# 0 i64 = I64# 0 w = W# (__word 0) w8 = W8# (__word 0) w16 = W16# (__word 0) w32 = W32# (__word 0) w64 = W64# (__word 0) z2 = $w$cbit 0 z1 = complementInteger z2 z = andInteger z2 z1 }}} Thus, `i` and `z` are not properly constant-folded in GHC 7.8.1RC2. With GHC 7.6.3, however, `i` and `z` were properly folded to `0`: {{{#!haskell -- GHC 7.6.3 i = I# 0 i8 = case $fBitsInt8_$cbit i of _ { I8# x#_aDf -> case $fBitsInt8_$cbit i of _ { I8# x#1_aDr -> I8# (word2Int# (and# (int2Word# x#_aDf) (xor# (int2Word# x#1_aDr) (__word 18446744073709551615)))) } } i16,i32,i64 -- equivalent to i8 w = W# (__word 0) w8 = case $fBitsWord8_$cbit i of _ { W8# x#_aEV -> case $fBitsWord8_$cbit i of _ { W8# x#1_aF5 -> W8# (and# x#_aEV (xor# x#1_aF5 (__word 255))) } } w16,w32,w64 -- equivalent to w8 z = __integer 0 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8832> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10596: Template Haskell : getQ and putQ doesn't work
by GHC 23 Sep '15

23 Sep '15

#10596: Template Haskell : getQ and putQ doesn't work -------------------------------------+------------------------------------- Reporter: kiripon | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 7.10.1 Haskell | Operating System: Unknown/Multiple Keywords: getQ putQ | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Functions `getQ` and `putQ` in the module `Language.Haskell.TH.Syntax` do not work. Following code is an example of this problem. The variable `x` should be `(Just B)`, but `x` is `Nothing`. {{{#!hs {-# LANGUAGE TemplateHaskell #-} module X where import Language.Haskell.TH import Language.Haskell.TH.Syntax do putQ (100 :: Int) x <- getQ :: Q (Maybe Int) -- It should print "Just 100" but "Nothing" runIO $ print x return [] }}} As a result, I get following output on compile. {{{#!hs $ ghc -fforce-recomp X.hs [1 of 1] Compiling X ( X.hs, X.o ) Nothing }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10596> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10590: RTS failing with removeThreadFromDeQueue: not found message
by GHC 23 Sep '15

23 Sep '15

#10590: RTS failing with removeThreadFromDeQueue: not found message -------------------------------------+------------------------------------- Reporter: qnikst | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Under certain circumstances I'm facing RTS error, this happens when one thread is reading socket and another one closes it. Seems like that it happens when smth else is involved as I failed to trim this example Error that I see: {{{ % ./test nid://127.0.0.1:8080:0 1 test: internal error: removeThreadFromDeQueue: not found (GHC version 7.10.1 for x86_64_unknown_linux) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug zsh: abort ./test }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10590> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10660: .dyn_o isn't generated for .hsig files with -dynamic-too
by GHC 23 Sep '15

23 Sep '15

#10660: .dyn_o isn't generated for .hsig files with -dynamic-too -------------------------------------+------------------------------------- Reporter: spinda | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- This causes the linker to error out later on, as it expects a .dyn_o file to exist for each .hsig file. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10660> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10689: compiling singletons-1.1.2.1 as -O1 -fspec-constr fails as 'Template variable unbound in rewrite rule'
by GHC 23 Sep '15

23 Sep '15

#10689: compiling singletons-1.1.2.1 as -O1 -fspec-constr fails as 'Template variable unbound in rewrite rule' -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2-rc2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- First observed on singletons-1.1.2.1 package ghc-7.10.2. I've tried to distill it down to a single file. The file manages to crash both GHC and GHCi. GHCi: {{{ $ inplace/bin/ghc-stage2 -hide-all-packages -package=base --interactive List.hs GHCi, version 7.11.20150723: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling List ( List.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150723 for x86_64-unknown-linux): floatExpr tick break<2>() Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} GHC: {{{ $ inplace/bin/ghc-stage2 -hide-all-packages -package=base --make List.hs -dsuppress-all -dsuppress-uniques [1 of 1] Compiling List ( List.hs, List.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.11.20150723 for x86_64-unknown-linux): Template variable unbound in rewrite rule m [a_afdP, x, m, ipv, ipv, sc, sc, sc, sg] [a_afdP, x, m, ipv, ipv, sc, sc, sc, sg] [TYPE a_afdP, TYPE x, TYPE Let1627448493XsSym4 x m ipv ipv, sc, (SCons @~ ... sc sc) `cast` ...] [TYPE a_afdP, TYPE x, TYPE Let1627448493XsSym4 x ipv ipv ipv, sc, (SCons @~ ... ipv ipv) `cast` ...] Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} The "minimal" single-file sample is attached. If you need original selfcontained reproducer (79 modules, template haskell code) this is the version i've started with: http://code.haskell.org/~slyfox/unbound-template-var.tar.gz Adjusting path to GHC in '''./trigger-a-bug.bash''' should be enough. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10689> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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