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[GHC] #13245: Default FD buffer size is not a power of 2
by GHC 26 Feb '17

26 Feb '17

#13245: Default FD buffer size is not a power of 2 -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.0.2 System | 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: -------------------------------------+------------------------------------- From https://hackage.haskell.org/package/base-4.9.1.0/docs/src/GHC.IO.FD.html {{{ -- We used to use System.Posix.Internals.dEFAULT_BUFFER_SIZE, which is -- taken from the value of BUFSIZ on the current platform. This value -- varies too much though: it is 512 on Windows, 1024 on OS X and 8192 -- on Linux. So let's just use a decent size on every platform: dEFAULT_FD_BUFFER_SIZE :: Int dEFAULT_FD_BUFFER_SIZE = 8096 }}} 8096 is not a power of two, and does not agree with the original commit message that sets it to 8KB (https://github.com/ghc/ghc/blame/master/libraries/base/GHC/IO/FD.hs#L119) Confirmed by Simon Marlow on IRC that this is a typo, a mix between 8192 and 4096. I'll send a patch to set it to 8192. It would be nice if the fix could be released in both GHC 8.2 and and 8.0.3. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13245> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] Batch modify: #12100, #12776, #12944, #13242, #7411, #11606, ...
by GHC 26 Feb '17

26 Feb '17

Batch modification to #12100, #12776, #12944, #13242, #7411, #11606, #11959, #12150, #12425, #12610, #1851, #6132, #11525, #11731, #11827, #11954, #12021, #12090, #12193, #12234, #12737, #12846, #12885, #12921, #12940, #12985, #13025, #13035, #13043, #13050, #13056, #13083, #13135, #13245, #13246, #13285, #12055 by bgamari: milestone to 8.2.1 Comment: At this point it is rather unlikely that there will be an 8.0.3. Re-milestoning. -- Tickets URL: <http://ghc.haskell.org/trac/ghc/query?id=12100%2C12776%2C12944%2C13242%2C74…> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12680: Permit type equality instances in signatures
by GHC 25 Feb '17

25 Feb '17

#12680: Permit type equality instances in signatures -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 8.1 (Type checker) | Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- David Christiansen requested this, and I want to record it so I don't forget. What he wants to be able to do is say things like this in signatures: {{{ signature A where data T data S type family F a instance T ~ S instance F Int ~ S }}} This is currently rejected by GHC because you are not allowed to define instances of type equality. But really all this is saying is that the type equality must hold when we eventually implement the module; easy to check. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12680> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13250: Backpack: matching newtype selectors doesn't work
by GHC 25 Feb '17

25 Feb '17

#13250: Backpack: matching newtype selectors doesn't work -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.1 (Type checker) | Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ unit p where signature A where newtype F a = F { mkF :: a } unit q where module A where newtype F a = F { mkF :: a } unit r where dependency p[A=q:A] }}} fails with {{{ ezyang@sabre:~$ ghc-head --backpack selector.bkp -dppr-debug [1 of 3] Processing p [2 of 3] Processing q Instantiating q [1 of 1] Compiling A ( q/A.hs, q/A.o ) [3 of 3] Processing r Instantiating r [1 of 1] Including p[A=q:A] Instantiating p[A=q:A] [1 of 1] Compiling A[sig] ( p/A.hsig, p/p-HVmFlcYSefiK5n1aDP1v7x/A.o ) ghc: panic! (the 'impossible' happened) (GHC version 8.1.20170123 for x86_64-unknown-linux): TcIface.find_lbl missing: mkF{v} known labels: [mkF{q:A.mkF{v rb}}] Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1166:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1170:37 in ghc:Outputable pprPanic, called at compiler/iface/TcIface.hs:841:41 in ghc:TcIface }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13250> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13334: Constant folding for repeated integer operation of unknown value
by GHC 25 Feb '17

25 Feb '17

#13334: Constant folding for repeated integer operation of unknown value -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: feature | Status: new request | Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Runtime Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- While looking at Phab:D3197 I noticed that currently there is nothing to turn an expression of the form `n+n+...+n` into `n*m`. It seems like some rules like, {{{ forall x. x +# x = 2*x forall n x. n*x + x = (n+1) * x forall n x. x + n*x = (n+1) * x }}} Might fix this. Of course, it's quite possible that a string of additions **is** sometimes faster than a multiplication, but it seems to me that we should (for integer types) perform the rewrite to multiplication and then teach the code generator to lower to addition if it deems it advantageous. Naturally, this also applies to other integer operators as well. Regardless, I doubt that this is hurting anyone too badly. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13334> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13305: static: check for identifiers should only consider term level variables
by GHC 25 Feb '17

25 Feb '17

#13305: static: check for identifiers should only consider term level variables -------------------------------------+------------------------------------- Reporter: edsko | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 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 {{{#!hs {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE StaticPointers #-} module Main where import Data.Proxy import GHC.StaticPtr foo :: forall a. StaticPtr (Proxy a) foo = static (Proxy :: Proxy a) main :: IO () main = putStrLn "Hi" }}} This yields {{{ Only identifiers of top-level bindings can appear in the body of the static form: static (Proxy :: Proxy a) but the following identifiers were found instead: a }}} but `a` is a type-level variable and therefore by definition static. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13305> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12971: gcc not finding default temporary directory
by GHC 25 Feb '17

25 Feb '17

#12971: gcc not finding default temporary directory -------------------------------------+------------------------------------- Reporter: erikprantare | Owner: Type: feature | Status: new request | 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: -------------------------------------+------------------------------------- Hello, I've been trying to get the ghc to compile a .hs file to binary. I get an error that seems to be caused during the C compilation phase from the special character ä in my user directory. When compiling I get this: {{{ C:\Users\Erik Präntare>ghc C:\code\Haskell\test.hs Linking C:\code\Haskell\test.exe ... realgcc.exe: error: C:\Users\Erik Pr├ñntare\AppData\Local\Temp\ghc28912_0\ghc_1. c: No such file or directory realgcc.exe: fatal error: no input files compilation terminated. `gcc.exe' failed in phase `C Compiler'. (Exit code: 1) }}} Notice how it says Pr├ñntare instead of Präntare. The UTF-8 encoding for ä is 0xC3 0xA4 which, surprise surprise, corresponds to ├ñ in ASCII. Now, I managed to get around this by changing the tmpdir to my actual temporary directory, but as a new user of ghc it was very troublesome to find a solution. Maybe consider changing the default tmpdir, at least if special characters are encountered? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12971> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13315: Compile broken on new MSYS2
by GHC 25 Feb '17

25 Feb '17

#13315: Compile broken on new MSYS2 -------------------------------------+------------------------------------- Reporter: Phyx- | Owner: (none) Type: bug | Status: new Priority: high | Milestone: Component: Build System | Version: 8.0.1 Keywords: | Operating System: Windows Architecture: | Type of failure: Building GHC Unknown/Multiple | failed Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- February comes with a major change in behavior for MSYS2/Cygwin. Tools such as awk/sed etc now use binary mode unless on a text mount: https://cygwin.com/ml/cygwin-announce/2017-02/msg00036.html This is problematic because GHC etc only use the underlying OS to determine how to output line endings. As such we output \r\n but in sed et al $ will no longer match line endings. Which means out scripts are currently broken. The build will fail with errors such as {{{ [00:09:33][Step 2/6] utils/hp2ps/dist/build/.depend.c_asm:2: *** missing separator. Stop. [00:09:33][Step 2/6] make: *** [Makefile:125: all] Error 2 }}} This is because the `--make-depends` output from GHC will write a file using `\r\n` newlines which `sed` et al will no longer match with `$`. This change is pretty catastrophic in that it also applies to piped data from stdout/stderr. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13315> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13196: Document AMP as a deviation from Haskell 2010
by GHC 25 Feb '17

25 Feb '17

#13196: Document AMP as a deviation from Haskell 2010 -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Documentation | Version: 8.0.1 Keywords: AMP | Operating System: Unknown/Multiple Architecture: | Type of failure: Documentation Unknown/Multiple | bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The `Applicative` class is not in Haskell 2010, and is certainly not a superclass of `Monad` there. This must be documented as a deviation in the user's guide. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13196> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] Trac email verification for user: _recursion
by GHC 24 Feb '17

24 Feb '17

Please visit the following URL to confirm your email address. Verification URL: <http://ghc.haskell.org/trac/ghc/verify_email?verify=1&token=Zf4Wsroc> Username: _recursion Verification Token: Zf4Wsroc -- GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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