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[GHC] #8346: Rank 1 type signature still requires RankNTypes
by GHC 12 Jul '17

12 Jul '17

#8346: Rank 1 type signature still requires RankNTypes ----------------------------+---------------------------------------------- Reporter: | Owner: tinctorius | Status: new Type: bug | Milestone: Priority: normal | Version: 7.6.3 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: GHC rejects valid program Architecture: | Test Case: Unknown/Multiple | Blocking: Difficulty: Unknown | Blocked By: | Related Tickets: #2605 | ----------------------------+---------------------------------------------- When trying to figure out which type variable names are *actually* bound in `ScopedTypeVariables`, I tried floating `forall`s into the covariant argument of the function type. Essentially, I ran into the problem that programs like the following are rejected: {{{ #!hs {-# LANGUAGE ExplicitForAll #-} tuple :: forall a. a -> (forall b. b -> (a, b)) tuple = (,) }}} The message is as follows: {{{ Main.hs:2:10: Illegal polymorphic or qualified type: forall b. b -> (a, b) Perhaps you intended to use -XRankNTypes or -XRank2Types In the type signature for `tuple': tuple :: forall a. a -> (forall b. b -> (a, b)) }}} As far as I know, the rank of a type is defined by how deep quantifiers are nested in contravariant parts of that type. Or something like that. Also, as far as I know, `forall a. a -> (forall b. b -> (a, b))` is equivalent to `forall a b. a -> b -> (a, b)`, and more importantly, both are rank-1 polymorphic. There should be no need to use extensions that allow higher-ranked polymorphism. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8346> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13949: Haddock fails to typecheck an example with TemplateHaskell
by GHC 12 Jul '17

12 Jul '17

#13949: Haddock fails to typecheck an example with TemplateHaskell -------------------------------------+------------------------------------- Reporter: duog | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.3 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: -------------------------------------+------------------------------------- Reported by leftaroundabout at [https://github.com/haskell/haddock/issues/650] Surely this is a bug in GhcMake.enableCodegenForTH introduced in 53c78be0aab76a3107c4dacbb1d177afacdd37fa. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13949> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13818: ANN pragmas and -static fail to compile
by GHC 12 Jul '17

12 Jul '17

#13818: ANN pragmas and -static fail to compile -------------------------------------+------------------------------------- Reporter: duog | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 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: -------------------------------------+------------------------------------- A Haskell source file with an ANN pragma will fail to compile with -static if any packages do not have dynamic libraries installed. Reproduction: {{{ $ echo "module Bug where {-# ANN module "just a string" #-}" > Bug.hs $ cabal sandbox init $ cabal install transformers-compat --disable-shared $ ghc -static -package db ./.cabal-sandbox/x86_64-linux- ghc-8.2.0.20170522-packages.conf.d -package transformers-compat -c Bug.hs <command line>: can't load .so/.DLL for: libHStransformers- compat-0.5.1.4-DQiwI4tzfvoKHf8rERr8Q2.so (libHStransformers- compat-0.5.1.4-DQiwI4tzfvoKHf8rERr8Q2.so: cannot open shared object file: No such file or directory) $ cabal install transformers-compat --enable-shared --reinstall $ ghc -static -package db ./.cabal-sandbox/x86_64-linux- ghc-7.10.3-packages.conf.d -package transformers-compat -c Bug.hs -fforce-recomp }}} Presumably the ANN pragma causes ghci to load with all libraries which must be dynamic. Not sure which category is correct for Type of failure. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13818> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13937: @progbits is used incorrectly throughout GHC
by GHC 12 Jul '17

12 Jul '17

#13937: @progbits is used incorrectly throughout GHC -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) 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: -------------------------------------+------------------------------------- GHC uses `.section $SECTION_NAME,$FLAGS,@progbits` directives throughout its produced assembler. However, some architectures (e.g. ARM) use `@` as a comment character and therefore must use some other prefix for section types. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13937> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13568: Name is reported as ambiguous and not in scope
by GHC 12 Jul '17

12 Jul '17

#13568: Name is reported as ambiguous and not in scope -------------------------------------+------------------------------------- Reporter: mpickering | Owner: (none) 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: -------------------------------------+------------------------------------- {{{ module A where data T = A }}} {{{ module B where import A data S = A foo :: A -> () foo = undefined }}} Compiling this example, the usage of `A` in `foo` is reported as both ambiguous and out of scope. I haven't mentioned data kinds at all so `A` should certainly refer to a type constructor which isn't in scope. The problem is that `DataKinds` is checked too late in `lookup_demoted`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13568> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13922: Sort output of failed tests.
by GHC 12 Jul '17

12 Jul '17

#13922: Sort output of failed tests. -------------------------------------+------------------------------------- Reporter: AndreasK | Owner: (none) Type: task | Status: new Priority: lowest | Milestone: Component: Test Suite | Version: 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: -------------------------------------+------------------------------------- The summary for failed tests can vary between runs. Sorting the output of {{{ "Unexpected results from: TEST="t1 t2..." }}} makes it easier to check for specific tests and to compare one run quickly with the result of another. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13922> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12390: List rules for `Coercible` instances
by GHC 12 Jul '17

12 Jul '17

#12390: List rules for `Coercible` instances -------------------------------------+------------------------------------- Reporter: Iceland_jack | 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: -------------------------------------+------------------------------------- `:info` on [https://downloads.haskell.org/~ghc/7.8.2/docs/html/libraries/base-4.7.0.0 /Data-Coerce.html#t:Coercible Data.Coerce.Coercible] doesn't display any instances, it's a special class so it should be special-cased {{{ ghci> :i Coercible type role Coercible representational representational class a ~R# b => Coercible (a :: k) (b :: k) -- Defined in ‘GHC.Types’ }}} The base case would be easy to display: {{{#!hs instance Coercible a a -- Generated on the fly }}} but it's trickier to describe the … instance succinctly: {{{#!hs instance Coercible b b' => Coercible (D a b c) (D a b' c') }}} same for newtypes. ---- Maybe it's better to list concrete examples {{{#!hs coerce @(Reader _ _) :: Reader a b -> (a -> Identity b) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12390> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13830: '+RTS -s' gives incorrect value for work balance in some cases
by GHC 12 Jul '17

12 Jul '17

#13830: '+RTS -s' gives incorrect value for work balance in some cases -------------------------------------+------------------------------------- Reporter: duog | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 8.0.1 System | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Debugging Unknown/Multiple | information is incorrect Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The formula for work balance as printed by the rts -s flag does not account for the possibility of the number of capabilities changing. Nor does it account for the number of garbage collection threads being other than n_capabilities. The attached program demonstrates the first problem, with instructions for replication in comments. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13830> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13919: Incorrect unused top binding warning when interacting with GHC.Generics
by GHC 12 Jul '17

12 Jul '17

#13919: Incorrect unused top binding warning when interacting with GHC.Generics -------------------------------------+------------------------------------- Reporter: Taneb | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect Unknown/Multiple | error/warning at compile-time Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The program {{{#!hs {-# LANGUAGE DeriveGeneric #-} module Main (main) where import Data.Aeson import GHC.Generics data Foo = Foo {bar :: String} deriving Generic instance ToJSON Foo where toJSON = genericToJSON defaultOptions main :: IO () main = print (toJSON (Foo "hello")) }}} emits the warning {{{ UTB.hs:7:17: warning: [-Wunused-top-binds] Defined but not used: ‘bar’ }}} but removing that binding changes the behaviour of the program, as the above prints {{{ Object (fromList [("bar",String "hello")]) }}} but {{{#!hs {-# LANGUAGE DeriveGeneric #-} module Main (main) where import Data.Aeson import GHC.Generics data Foo = Foo String deriving Generic instance ToJSON Foo where toJSON = genericToJSON defaultOptions main :: IO () main = print (toJSON (Foo "hello")) }}} prints {{{ String "hello" }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13919> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1: Implicit parameters cause strange behavi
by GHC 12 Jul '17

12 Jul '17

#1: Implicit parameters cause strange behavi --------------------------------+-------------------- Reporter: nobody | Owner: nobody Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 5.0 Resolution: Fixed | Keywords: Type of failure: None/Unknown | --------------------------------+-------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"b8f33bc6b738b0378976e42b79369f0e53b680c7/ghc" b8f33bc6/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="b8f33bc6b738b0378976e42b79369f0e53b680c7" Always allow -staticlib the `-staticlib` flag is currently only supported on apple platforms, due to the avaiablity of libtool (the apple version, which is unlike the gnu version). This however prevents the use of -staticlib in cases where it would be beneficial as well. The functionality that `-staticlib` uses from `libtool` can be stubbed with a small script like the following: ``` #!/bin/bash # This script pretends to be libtool. And supports # only a limited set of flags. # # It is supposed to be a stand in for libtool -static, whic # creates a static archive. This is done by locating all -l<lib> # libs in the provied -L<lib path> library paths, and building an # MRI script to create the final archive from all the libraries, and # other provided inputs. # name=${0##*/} target=${name%-*} set -e ldflags_L=() ldflags_l=() output="" inputs=() STATIC=0 DYNAMIC=1 mode=$DYNAMIC verbose=0 # find_lib <name> path path path path function find_lib () { lib=$1; shift 1; for dir in $@; do if [ -f "$dir/$lib" ]; then echo "$dir/$lib" break fi done } while [ "$#" -gt 0 ]; do case "$1" in -v|--verbose) verbose=1; shift 1;; -o) output="$2"; shift 2;; -L*) ldflags_L+=("${1:2:${#1}-2}"); shift 1;; -l*) ldflags_l+=("lib${1:2:${#1}-2}.a"); shift 1;; -static) mode=$STATIC; shift 1;; -dynamic) mode=$DYNAMIC; shift 1;; -Wl,*) ldflags+=("${1#*,}"); shift 1;; -*) echo "unknown option: $1" >&2; exit 1;; *) inputs+=("$1"); shift 1;; esac done if [ ! $mode == $STATIC ]; then echo "-dynamic not supported!" >&2; exit 1; fi MRI="create ${output}\n" for input in "${ldflags_l[@]}"; do lib=$(find_lib $input ${ldflags_L[@]}) if [ -z $lib ]; then echo "Failed to find lib $input" >&2 exit 1 else MRI+="addlib $lib\n" continue fi done for input in "${inputs[@]}"; do MRI+="addmod $input\n" done MRI+="save\nend\n" echo -e "$MRI" | $target-ar -M $target-ranlib $output ``` if `ar` supports MRI scripts. Reviewers: austin, bgamari Reviewed By: bgamari Subscribers: rwbarton, thomie Differential Revision: https://phabricator.haskell.org/D3706 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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