December 2016 - ghc-tickets

[GHC] #12565: unhelpful error message about enabling TypeApplications
by GHC 14 Sep '18

14 Sep '18

#12565: unhelpful error message about enabling TypeApplications -------------------------------------+------------------------------------- Reporter: mauke | Owner: Type: bug | Status: new 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: -------------------------------------+------------------------------------- {{{ % cat bug.hs }}} {{{#!hs {-# LANGUAGE TypeApplications #-} main = return (id@() ()) }}} {{{ % ghc bug.hs [1 of 1] Compiling Main ( bug.hs, bug.o ) bug.hs:2:16: error: Pattern syntax in expression context: id@() Did you mean to enable TypeApplications? }}} This error message makes no sense because `TypeApplications` is already enabled. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12565> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 2

[GHC] #11143: Feature request: Add index/read/write primops with byte offset for ByteArray#
by GHC 14 Sep '18

14 Sep '18

#11143: Feature request: Add index/read/write primops with byte offset for ByteArray# -------------------------------------+------------------------------------- Reporter: vagarenko | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.2.1 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 Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently, primops for indexing `ByteArray#` and reading/writing `MutableByteArray#` have the following form: {{{#!hs indexTYPEArray# :: ByteArray# -> Int# -> TYPE# readTYPEArray# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, TYPE##) writeTYPEArray# :: MutableByteArray# s -> Int# -> TYPE# -> State# s -> State# s }}} where second argument of type `Int#` is an offset measured in terms of the size of `TYPE#`. This is inconvinient if I want to store values of different types inside `ByteArray#`: I have to read values of type `Int8` and then glue them together with some bitwise operations. I suggest adding number of primops, similar to existing ones, which would accept offset in bytes from the start of the `ByteArray#`: {{{#!hs -- | Read 8-bit integer; offset in bytes. indexByteInt8Array# :: ByteArray# -> Int# -> Int# -- | Read 16-bit integer; offset in bytes. indexByteInt16Array# :: ByteArray# -> Int# -> Int# -- | Read 32-bit integer; offset in bytes. indexByteInt32Array# :: ByteArray# -> Int# -> Int# -- | Read 8-bit integer; offset in bytes. readInt8Array# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, Int##) -- | Read 16-bit integer; offset in bytes. readInt16Array# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, Int##) -- | Read 32-bit integer; offset in bytes. readInt32Array# :: MutableByteArray# s -> Int# -> State# s -> (#State# s, Int##) }}} and so on... -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11143> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 17

[GHC] #10700: include/stg/Prim.h isn't C++ compatible
by GHC 14 Sep '18

14 Sep '18

#10700: include/stg/Prim.h isn't C++ compatible -------------------------------------+------------------------------------- Reporter: Fabian | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Build | Version: 7.10.1 System | Keywords: FFI | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- StgWord hs_cmpxchg8(volatile StgWord8 *x, StgWord old, StgWord new); and a few other declarations in Prim.h causes problems as they use ''new'' as a variable name. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10700> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 8

[GHC] #10833: Use injective type families when dealing with givens
by GHC 14 Sep '18

14 Sep '18

#10833: Use injective type families when dealing with givens -------------------------------------+------------------------------------- Reporter: jstolarek | Owner: jstolarek Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: #6018 Differential Revisions: | -------------------------------------+------------------------------------- Consider this code: {{{#!hs type family Id a = r | r -> a id :: (Id a ~ Id b) => a -> b id x = x }}} GHC currently rejects it because it does not use type family injectivity information when dealing with the given constraints. Implementing this requires changing Core. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10833> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 12

[GHC] #12420: Users guide link for hsc2hs has bitrotten
by GHC 13 Sep '18

13 Sep '18

#12420: Users guide link for hsc2hs has bitrotten -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: task | Status: new Priority: normal | Milestone: Component: hsc2hs | 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: -------------------------------------+------------------------------------- https://hackage.haskell.org/package/hsc2hs links to http://www.haskell.org/ghc/docs/latest/html/users_guide/hsc2hs.html which is dead. I think https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/utils.html #writing-haskell-interfaces-to-c-code-hsc2hs is what is desired. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12420> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 2

[GHC] #11197: Overeager deferred type errors
by GHC 11 Sep '18

11 Sep '18

#11197: Overeager deferred type errors -------------------------------------+------------------------------------- Reporter: goldfire | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: 8.0.1 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 Rev(s): | Wiki Page: -------------------------------------+------------------------------------- With `TypeInType`, the solver now works in terms of unlifted equality. The only place this matters is in deferred type errors, which now are more eager than they were before. For example: {{{ {-# OPTIONS_GHC -fdefer-type-errors #-} module Main where main = do putStrLn "Hi there." putStrLn True }}} This used to print {{{ Hi there. Defer: Defer.hs:7:12: error: ... }}} Now it prints {{{ Defer: Defer.hs:7:12: error: ... }}} No more `Hi there.`. Thinking about Core, this change should be expected. GHC puts all evidence bindings for `main` at the top, and with unlifted equality in the solver, these bindings now contain `case typeError ... of ...`, which forces the type error eagerly. Previously, there was a lazy binding for a lifted equality witness, unpacked only at the last moment by magic in the desugarer, thus the lazier warning. Simon has proposed customizing the !FloatIn pass to deal with this scenario. I do believe this would work nicely, but I have not yet implemented it. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11197> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 17

[GHC] #12833: GHCi
by GHC 10 Sep '18

10 Sep '18

#12833: GHCi -------------------------------------+------------------------------------- Reporter: Iceland_jack | 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: -------------------------------------+------------------------------------- In multiline mode you can define a multi-line Haskell function: {{{ Prelude> :set +m Prelude> let Prelude| f :: Int -> Int Prelude| f 0 = 0 Prelude| f n = n - 1 Prelude| Prelude> }}} Is there a reason why it couldn't work with other things like {{{ Prelude> :set -XPatternSynonyms Prelude> let Prelude| pattern A = 'A' Prelude| <interactive>:27:1: error: Illegal pattern synonym declaration for ‘A’ Pattern synonym declarations are only valid at top level }}} {{{ Prelude> let Prelude| data A Prelude| = B Prelude| | C Int Prelude| <interactive>:30:1: error: parse error (possibly incorrect indentation or mismatched brackets) }}} {{{ Prelude> let Prelude| type A = Int Prelude| <interactive>:48:1: error: parse error (possibly incorrect indentation or mismatched brackets) }}} couldn't work, similar to how they work with `:{` and `:}`: {{{ Prelude> :{ Prelude| data A Prelude| = B Prelude| | C Int Prelude| :} Prelude> }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12833> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 2

[GHC] #12578: Update links to SPJ’s papers
by GHC 09 Sep '18

09 Sep '18

#12578: Update links to SPJ’s papers -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Documentation | Version: 8.1 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: -------------------------------------+------------------------------------- It seems that Simon’s homepage got restructured, and a lot of links in the documentation and the code comments are not valid any more. At least these need to be looked at: {{{ $ git grep 'people/simonpj' compiler/types/FamInstEnv.hs:http://research.microsoft.com/en- us/um/people/simonpj/papers/ext-f/axioms-extended.pdf compiler/types/Unify.hs:[1]: http://research.microsoft.com/en- us/um/people/simonpj/papers/ext-f/axioms-extended.pdf docs/core-spec/core-spec.mng:phantom equality includes all types. See \url{http://ghc.haskell.org/trac/ghc/wiki/Roles} and \url{http://research.microsoft.com/en- us/um/people/simonpj/papers/ext-f/coercible.pdf} docs/users_guide/glasgow_exts.rst:paper <http://research.microsoft.com/en- us/um/people/simonpj/papers/ext-f/>`__. docs/users_guide/glasgow_exts.rst:cloud <http://research.microsoft.com/en- us/um/people/simonpj/papers/parallel/remote.pdf>`__, docs/users_guide/using-optimisation.rst: multiprocessor <http://research.microsoft.com/en- us/um/people/simonpj/papers/parallel/>`__. docs/users_guide/using-optimisation.rst: (ICFP'96) <http://research.microsoft.com/en- us/um/people/simonpj/papers/float.ps.gz>`__. docs/users_guide/using-optimisation.rst: (ICFP'96) <http://research.microsoft.com/en- us/um/people/simonpj/papers/float.ps.gz>`__. docs/users_guide/using-optimisation.rst: programs <http://research.microsoft.com/en-us/um/people/simonpj/papers/spec- constr/index.htm>`__. docs/users_guide/using-optimisation.rst: thesis <http://research.microsoft.com/en-us/um/people/simonpj/papers/santos- thesis.ps.gz>`__ docs/users_guide/using-optimisation.rst: analyser <http://research.microsoft.com/en-us/um/people/simonpj/papers/simple- strictnes-analyser.ps.gz>`__, libraries/base/GHC/Arr.hs:-- http://research.microsoft.com/en- us/um/people/simonpj/papers/ext-f/coercible.pdf libraries/base/GHC/Base.hs:-- http://research.microsoft.com/en- us/um/people/simonpj/papers/ext-f/coercible.pdf testsuite/tests/dependent/should_compile/all.T:# http://research.microsoft.com/en-us/um/people/simonpj/papers/haskell- dynamic/ $ git grep '~simonpj' compiler/coreSyn/CoreSyn.hs:-- GHC uses System FC <http://research.microsoft.com/~simonpj/papers/ext-f/> for this purpose, docs/users_guide/bugs.rst: inliner <http://research.microsoft.com/~simonpj/Papers/inlining/>`__. docs/users_guide/glasgow_exts.rst: Languages <http://research.microsoft.com/~simonpj/Papers/slpj-book-1987/>`__. docs/users_guide/glasgow_exts.rst:"group by" <http://research.microsoft.com/~simonpj/papers/list-comp>`__, docs/users_guide/glasgow_exts.rst:space <http://research.microsoft.com/~simonpj/Papers/type-class-design- space/>`__ docs/users_guide/glasgow_exts.rst:papers <http://research.microsoft.com/~simonpj/papers/constraints/index.htm>`__ docs/users_guide/glasgow_exts.rst:Haskell <http://research.microsoft.com/~simonpj/papers/meta-haskell/>`__" docs/users_guide/glasgow_exts.rst:2 <http://research.microsoft.com/~simonpj/papers/meta-haskell/notes2.ps>`__. libraries/base/Control/Concurrent/MVar.hs:-- <http://research.microsoft.com/~simonpj/papers/concurrent-haskell.ps.gz "Concurrent Haskell"> libraries/base/GHC/Conc/Sync.hs:(<http://research.microsoft.com/~simonpj/Papers /asynch-exns.htm>). }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12578> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 12

[GHC] #10827: GHCi should support interpeting multiple packages/units with separate DynFlags
by GHC 07 Sep '18

07 Sep '18

#10827: GHCi should support interpeting multiple packages/units with separate DynFlags -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: GHC API | Version: 7.11 Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Stack and other tools are attempting to make the user-experience of developing multiple packages simultaneously better. Thus, if you have source packages p, q and r (which all depend on them), `stack build` builds all of them. They are quite interested in support `stack ghci` but there are problems: https://github.com/commercialhaskell/stack/issues/665 The essence of the problem is twofold: 1. If you ask GHCi to interpret modules from multiple packages (e.g. by having multiple source directories), GHCi currently only knows how to put all of them into the same home package. This will fail if two packages have a module with the same name; also, modules in the other packages will always see modules (even if they're supposed to be hidden). 2. A GHCi session only has one global set of dynamic flags, but each package may be compiled with its own set of DynFlags (e.g. package global LANGUAGE pragmas). This means the "default DynFlags" needs to be varied between packages. It's not too obvious to me how to fix (1) (at least, you'd have to make the HPT support sets of HomeModInfos from multiple packages), but (2) seems tractable: since we already track DynFlags on a per-module basis, we just have to arrange for a "package" level DynFlag to be applied to the correct ModSummarys. Similar functionality would be useful for Backpack. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10827> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 5

[GHC] #12356: StaticPointers support in GHCi
by GHC 07 Sep '18

07 Sep '18

#12356: StaticPointers support in GHCi -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.2.1 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: #12000 Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently GHCi does not support `-XStaticPointers`, which is quite annoying for those of us who actually use `-XStaticPointers` in day-to-day development. It would be great if GHCi could grow support for this extension. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12356> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

1 19