November 2015 - ghc-tickets

[GHC] #10798: Signatures with only types should not be included in unit keys
by GHC 14 Oct '16

14 Oct '16

#10798: Signatures with only types should not be included in unit keys -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: feature | Status: new request | Priority: normal | Milestone: ⊥ Component: Package | Version: 7.11 system | Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Suppose we want to modularize the dependence on `p` in this program: {{{ unit p where module A where data T = T mkT = T unit q where include p module B where import A bar = mkT }}} The obvious signature to write for `A` is: {{{ signature A where data T mkT :: T }}} But this presupposes an implementation of `A` which exports `T`. But `B` doesn't use any export of `T`, and an equally valid implementation would be if `T` was defined in some `Types` module and then imported here. But suppose we change our signature to be: {{{ signature A.Types where data T signature A where import A.Types mkT :: T }}} This is maximally general, but requires that the module which exports `T` be named `A.Types`. If someone puts the type anywhere else, we have to rename the signature to the real place it was defined, or make a dummy implementation module which reexports the type in question. Now there is a curious thing, which is that the choice of module we use to fill these extra signature modules currently influences the type identity of anything else in the unit. But we never rely on any code from these signatures: if I make two distinct dummy modules to set `T` to the same type, this really shouldn't have any impact (at all!) on the code generated. So, my suggestion is that if a signature contains only types (perhaps they could be named something else, like `tysignature`), they should not count towards the calculation of a unit key. This means that a user can freely create dummy modules to fill in these types when they are instantiating; all that is being done is helping Backpack figure out what the identities of types are. (If we wanted to be fancy, Backpack could even look inside type signatures to determine some types, but let's not go there for now.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10798> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9717: More lazy orphan module loading
by GHC 14 Oct '16

14 Oct '16

#9717: More lazy orphan module loading -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: normal | Milestone: 7.10.1 Component: Compiler (Type | Version: 7.9 checker) | Operating System: Keywords: backpack | Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Difficulty: Unknown | None/Unknown Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Currently, when we import a module, we eagerly load all of the orphan modules transitively reachable from it (TcRnDriver:tcRnImports). This is a bit of bummer: as module import hierarchies get deeper and deeper, we'll collect more and more orphan instances and load more and more modules eagerly. The idea is to try to arrange for an orphan module not to be loaded, unless we think that it might have a relevant instance. Instead of just recording a list of orphan modules transitively reachable from a module, we will also record a digest of what type classes and types the orphan provides instances for. (This will be similar to the data we record for `ifInstTys` in `IfaceClsInst`.) Now, when we do any operation involving instances, we check and see if there are also orphans which could provide relevant instances (based on the digest) and load those. If an instance could never have been used, we avoid loading its interface file entirely. This doesn't appear to help too much for type families, where we have to load all of the instances anyway in order to check for consistency. A choice to make: Should we record just the class, or also the types involved? It would be best if we could quickly conclude that there are no more instances to load, but this may be difficult if matching against types as well. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9717> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10860: The test `setnumcapabilities001` sometimes fails on Phabricator
by GHC 13 Oct '16

13 Oct '16

#10860: The test `setnumcapabilities001` sometimes fails on Phabricator -------------------------------------+------------------------------------- Reporter: thomie | Owner: simonmar Type: bug | Status: new Priority: high | Milestone: 7.12.1 Component: Runtime | Version: 7.10.2 System | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- {{{ setnumcapabilities001: internal error: ASSERTION FAILED: file rts/Schedule.c, line 406 }}} https://phabricator.haskell.org/harbormaster/build/5890/ Here it just timed out: https://phabricator.haskell.org/harbormaster/build/5904/?l=0 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10860> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10458: GHCi fails to load shared object (the 'impossible' happened)
by GHC 10 Oct '16

10 Oct '16

#10458: GHCi fails to load shared object (the 'impossible' happened) -----------------------------------------+--------------------------------- Reporter: rleslie | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: None/Unknown Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -----------------------------------------+--------------------------------- I have a project that uses two external libraries, namely `-lcrypt` and `-lpcre`. Building with `cabal` and running the resulting executable works as expected, but I'm having trouble starting a REPL in GHCi: {{{ % cabal repl Preprocessing executable 'etamoo' for EtaMOO-0.2.1.0... GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help /usr/bin/ld: dist/build/etamoo/etamoo-tmp/src/cbits/crypt.o: relocation R_X86_64_PC32 against undefined symbol `crypt' can not be used when making a shared object; recompile with -fPIC /usr/bin/ld: final link failed: Bad value collect2: error: ld returned 1 exit status }}} The error suggests I need `-fPIC`, and this seems to help the `-lcrypt` case, but now I get: {{{ % cabal repl --ghc-options="-fPIC" Preprocessing executable 'etamoo' for EtaMOO-0.2.1.0... GHCi, version 7.10.1: http://www.haskell.org/ghc/ :? for help ghc: panic! (the 'impossible' happened) (GHC version 7.10.1 for x86_64-unknown-linux): Loading temp shared object failed: /tmp/ghc21539_0/libghc21539_2.so: undefined symbol: pcre_callout Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} FYI the C type of `pcre_callout` is a little unusual: {{{ extern int (*pcre_callout)(pcre_callout_block *); }}} In other words it is a global variable (pointer to function), not a function itself. Any advice is welcome, including the proper way to start GHCi given these external dependencies, as well as on this apparent bug. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10458> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9877: ForeignImport coercion evaluated before typechecking
by GHC 09 Oct '16

09 Oct '16

#9877: ForeignImport coercion evaluated before typechecking -------------------------------------+------------------------------------- Reporter: varosi | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Windows Architecture: x86_64 (amd64) | Type of failure: Compile- Difficulty: Unknown | time crash Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Under Windows 8.1 x64 with Haskell Platform 2014.02 and EclipseFP I got: buildwrapper.exe: panic! (the 'impossible' happened) (GHC version 7.8.3 for x86_64-unknown-mingw32): ForeignImport coercion evaluated before typechecking on the first line of file that has: {{{ #!div style="font-size: 80%" Code highlighting: {{{#!haskell {-# LANGUAGE ForeignFunctionInterface, RankNTypes, OverloadedStrings, ScopedTypeVariables #-} module Persist( persistWrite, persistRead ) where import System.Win32.Types import Graphics.Win32.GDI.Types import Foreign.C.String import Foreign.Marshal.Array import Control.Exception foreign import ccall unsafe "SHGetFolderPathW" cSHGetFolderPathW :: HWND -> INT -> HANDLE -> DWORD -> CWString -> IO LONG }}} }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9877> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10881: internal error: evacuate: strange closure type 5101248
by GHC 09 Oct '16

09 Oct '16

#10881: internal error: evacuate: strange closure type 5101248 -------------------------------------+------------------------------------- Reporter: burbly | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 7.10.2 System | Keywords: strange | Operating System: Windows closure type 5101248 | Architecture: x86_64 | Type of failure: Runtime crash (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Running a compiled executable on some complex input is causing this: postparse.exe: internal error: evacuate: strange closure type 5101248 (GHC version 7.10.2 for x86_64_unknown_mingw32) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug Running under Cygwin on Windows 8.1, 64. I suspect this may be a memory-related issue, but it's hard to diagnose as postparse.exe is operating in a larger ecosystem. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10881> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9547: Empty constraint tuples are mis-kinded
by GHC 06 Oct '16

06 Oct '16

#9547: Empty constraint tuples are mis-kinded -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | 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: -------------------------------------+------------------------------------- Consider {{{ -- If :: forall k. 'Bool -> k -> k -> k type family If cond tru fls where If True tru fls = tru If False tru fls = fls foo :: If True () (Eq a) => a -> a foo = error "urk" }}} This should work fine. But we get {{{ Foo.hs:8:21: The third argument of `If' should have kind `*', but `Eq a' has kind `Constraint' In the type signature for `foo': foo :: If True () (Eq a) => a -> a }}} Reason: GHC is treating the `()` unit tuple as of kind `*`. Reason is that in the `HsTupleTy` case of `tc_hs_type` in `TcHsType`, we see {{{ -- In the [] case, it's not clear what the kind is, so guess * }}} And that guess is plain wrong in this case. Unfortunately I don't see an easy fix, but it's plain wrong as-is. Simon -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9547> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10163: Export typeRepKinds in Data.Typeable
by GHC 04 Oct '16

04 Oct '16

#10163: Export typeRepKinds in Data.Typeable -------------------------------------+------------------------------------- Reporter: | Owner: RyanGlScott | Status: new Type: feature | Milestone: request | Version: 7.10.1-rc3 Priority: normal | Operating System: Unknown/Multiple Component: | Type of failure: Other libraries/base | Blocked By: Keywords: | Related Tickets: Architecture: | Unknown/Multiple | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Now that {{{TypeRep}}} has a {{{[KindRep]}}} field internally, {{{Data.Typeable}}} should export {{{typeRepKinds}}} (alongside {{{typeRepTyCon}}} and {{{typeRepArgs}}}, which are currently exported) to allow users to access it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10163> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11054: GHC on Windows could not use more than 64 logical processors
by GHC 03 Oct '16

03 Oct '16

#11054: GHC on Windows could not use more than 64 logical processors -------------------------------------+------------------------------------- Reporter: varosi | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 7.10.2 System | Keywords: | Operating System: Windows Architecture: x86_64 | Type of failure: Runtime (amd64) | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I found that GHC runtime does not take advantage of processor groups under Windows. So it cannot use more than 64 logical processors (2x 18 core physical + HT). This is Reddit thread about: https://www.reddit.com/r/haskell/comments/3q1r0o/ghc_on_numa_72_core_2_proc… MSDN link https://msdn.microsoft.com/en- us/library/windows/desktop/dd405503(v=vs.85).aspx -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11054> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8870: GHC 7.8.0 RC2 fails when compiling a hello world program on Windows 7 32bits
by GHC 02 Oct '16

02 Oct '16

#8870: GHC 7.8.0 RC2 fails when compiling a hello world program on Windows 7 32bits ----------------------------+--------------------------------------- Reporter: facundoq | Owner: Type: bug | Status: new Priority: highest | Milestone: Component: Compiler | Version: 7.8.1-rc2 Keywords: | Operating System: Windows Architecture: x86 | Type of failure: Compile-time crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------+--------------------------------------- Windows shows a window that says "GHC has stopped working" when compiling a simple hello world. Steps to reproduce 1) Download GHC 7.8 RC2 (http://www.haskell.org/ghc/dist/7.8.1-rc2/ghc-7.8.0.20140228-i386 -unknown-mingw32.tar.bz2) 2) Extract the contents of the tar to folder $GHC$ 3) Add $GHC$\bin and $GHC$\mingw\bin folder to the PATH, add env var "LANG=C". 4) Create file test.hs with contents: main = putStrLn "Hello, World!" 5) run "ghc test.hs". Interestingly, the error is not deterministic, ie, after running the command several times the program gets compiled. When that happens, and ff the file test.o is not deleted, further attempts to compile run succesfully. GHCi appears to work normally (when doing simple tests). More details: http://stackoverflow.com/questions/22291739/cant-install-packages-with- cabal-using-ghc-7-8rc2-and-windows-7 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8870> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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