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[GHC] #10664: T8131 times out on master
by GHC 04 Aug '15

04 Aug '15

#10664: T8131 times out on master -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: normal | Milestone: 7.12.1 Component: Compiler | Version: 7.11 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- The testsuite test `codeGen/should_fail/T8131` appears to time out on the `master` branch as of today. This isn't counted as a testsuite failure as it is a should-fail test, but nevertheless something is not right as it doesn't terminate despite being allowed to run for several minutes. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10664> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3306: Improve syntax for GADT + records
by GHC 04 Aug '15

04 Aug '15

#3306: Improve syntax for GADT + records -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: feature request | Status: closed Priority: normal | Milestone: 6.12.1 Component: Compiler | Version: 6.10.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"30c981e135033840fe1b4bcab697b412369739d7/ghc" 30c981e1/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="30c981e135033840fe1b4bcab697b412369739d7" Removed deprecated syntax for GADT constuctors. Old syntax was deprecated 6 years ago in this commit 432b9c9322181a3644083e3c19b7e240d90659e7 by simonpj:"New syntax for GADT-style record declarations, and associated refactoring" discussed in Trac #3306. This patch removes 2 reduce/reduce conflicts in parser. Conflicting productions were: ``` gadt_constr -> con_list '::' sigtype gadt_constr -> oqtycon '{' fielddecls '}' '::' sigtype ``` Recursive inlining of `con_list` and `oqtycon` helped reveal the conflict: ``` gadt_constr -> '(' CONSYM ')' '::' sigtype gadt_constr -> '(' CONSYM ')' '{' fielddecls '}' '::' sigtype ``` between two types of GADT constructors (second form stands for deprecated syntax). Test Plan: `make fasttest`, one breakage TEST="records-fail" (parse error instead of typecheck error due to removal of deprecated syntax). Updated test. Reviewers: simonmar, bgamari, austin, simonpj Reviewed By: simonpj Subscribers: thomie, mpickering, trofi Differential Revision: https://phabricator.haskell.org/D1118 GHC Trac Issues: #3306 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3306#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10711: Defining mapM_ in terms of traverse_ causes substantial blow-up in ByteCodeAsm
by GHC 04 Aug '15

04 Aug '15

#10711: Defining mapM_ in terms of traverse_ causes substantial blow-up in ByteCodeAsm -------------------------------------+------------------------------------- Reporter: bgamari | Owner: bgamari Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: ghcirun004 | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Phab:D924 has proposed that we redefine `mapM_`, currently, {{{ mapM_ = foldr ((>>) . f) (return ()) }}} as, {{{ mapM_ = foldr ((*>) . f) (return ()) = traverse_ }}} as part of the AMP proposal. However, this appears to have severe effects on the performance characteristics of the `Assembler` monad defined in `ByteCodeAsm`. In particular, the `mapM_` use in `ByteCodeAsm.assembleBCO` blows up severely, increasing the runtime of the `ghcirun004` testcase from 4 seconds to over 5 minutes. Intriguingly, defining `(*>) = (>>)` in `Assembler`'s `Applicative` instance (as done in Phab:D1097) restores reasonable runtime. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10711> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10708: Rejection of constant functions defined using conditional pattern matching
by GHC 03 Aug '15

03 Aug '15

#10708: Rejection of constant functions defined using conditional pattern matching -------------------------------------+------------------------------------- Reporter: | Owner: HubertGaravel | Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Linux Architecture: x86 | Type of failure: GHC rejects | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Revisions: | -------------------------------------+------------------------------------- Hi, The Haskell program below is rejected, although it is correct. GHC gives the following error message: {{{ HASKELL/tricky.hs:12:1: Multiple declarations of `Main.d3' Declared at: HASKELL/tricky.hs:10:1 HASKELL/tricky.hs:11:1 HASKELL/tricky.hs:12:1 }}} I agree that the definition of d3 is tricky and useless, but it seems to be valid. This example was exctracted from Haskell code automatically produced by an in-house code generator. {{{#!hs data Nat = D0 | Succ Nat deriving (Show, Eq, Ord) d1 :: Nat d2 :: Nat d3 :: Nat d1 = (Succ D0) d2 | D0 == D0 = D0 d3 | D0 /= D0 = D0 d3 | (Succ D0) == D0 = D0 d3 | (Succ D0) /= D0 = (Succ D0) main = do print d1 print d2 print d3 }}} Best regards Hubert -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10708> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3699: Wildcards in type functions
by GHC 03 Aug '15

03 Aug '15

#3699: Wildcards in type functions -------------------------------------+------------------------------------- Reporter: | Owner: msosn MartijnVanSteenbergen | Type: feature request | Status: closed Priority: low | Milestone: 7.12.1 Component: Compiler (Type | Version: 6.10.4 checker) | Resolution: fixed | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1092 -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => closed * resolution: => fixed -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3699#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10586: GHC 7.10.1 panic due to wildcard in data family instance
by GHC 03 Aug '15

03 Aug '15

#10586: GHC 7.10.1 panic due to wildcard in data family instance -------------------------------------+------------------------------------- Reporter: | Owner: WrenThornton | Status: new Type: bug | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- The following simple program causes GHC 7.10.1 (for x86_64-apple-darwin) to panic (rnHsTyKi HsWildcardTy): {{{#!hs {-# LANGUAGE TypeFamilies, GADTs, DataKinds, PolyKinds #-} data MyKind = A | B data family Sing (a :: k) data instance Sing (_ :: MyKind) where SingA :: Sing A SingB :: Sing B }}} Because data family instances must be fully saturated, we must give some name to the parameter; but because our instance is a GADT, the name of that parameter is meaningless, so using the wildcard makes complete sense here. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10586> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3699: Wildcards in type functions
by GHC 03 Aug '15

03 Aug '15

#3699: Wildcards in type functions -------------------------------------+------------------------------------- Reporter: | Owner: msosn MartijnVanSteenbergen | Type: feature request | Status: new Priority: low | Milestone: 7.12.1 Component: Compiler (Type | Version: 6.10.4 checker) | Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1092 -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"d9d2102ea7f6da1bc3a69fa469b89ea843cb8b02/ghc" d9d2102e/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="d9d2102ea7f6da1bc3a69fa469b89ea843cb8b02" Support wild cards in data/type family instances Handle anonymous wild cards in type or data family instance declarations like unnamed type variables. For instance (pun intented): type family F (a :: *) (b :: *) :: * type instance F Int _ = Int Is now the same as: type family F (a :: *) (b :: *) :: * type instance F Int x = Int Note that unlike wild cards in partial type signatures, no errors (or warnings with -XPartialTypeSignatures) are generated for these wild cards, as there is nothing interesting to report to the user, i.e. the inferred kind. Only anonymous wild cards are supported here, named and extra-constraints wild card are not. Test Plan: pass new tests Reviewers: goldfire, austin, simonpj, bgamari Reviewed By: simonpj, bgamari Subscribers: goldfire, thomie Differential Revision: https://phabricator.haskell.org/D1092 GHC Trac Issues: #3699, #10586 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3699#comment:24> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10134: Pattern Matching Causes Infinite Type Error
by GHC 03 Aug '15

03 Aug '15

#10134: Pattern Matching Causes Infinite Type Error -------------------------------------+------------------------------------- Reporter: dongen | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Howsagoin, This is a report about ghci (7.8.4) with CLaSH 0.4.1 I have a collection of modules that show an odd error. I don't want to send them to the list but I can send them to the developers if they think the described behaviour is definitely an error, which I suspect it is. When I write: > (a,b) = expression I get a type error about an occurs check: cannot construct infinite type: t0 ~ (t0 + 1) -1. The error message doesn't mention t0. However, when I leave out the pattern matching on the tuple and write > var = expression > a = fst var > b = snd var where var is a fresh variable, everything is fine. This is odd, because all I did was stripping off the pattern matching. To make sure, I also tried > var = expression > (a,b) = var This also gave the same type checking error. If there's anybody willing to have a look at this, please feel free to contact me by email. If you think I should produce a small example, also please let me know, but please note that it already took me several hours before I found that leaving out the pattern matching solved the problem:-( TIA for your time. Marc van Dongen dongen(a)cs.ucc.ie -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10134> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10722: GHC generates wrong unused type argument warning(ScopedTypeVariables related)
by GHC 03 Aug '15

03 Aug '15

#10722: GHC generates wrong unused type argument warning(ScopedTypeVariables related) -------------------------------------+------------------------------------- Reporter: osa1 | Owner: 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: | -------------------------------------+------------------------------------- {{{#!hs {-# LANGUAGE KindSignatures, ScopedTypeVariables #-} {-# OPTIONS_GHC -Wall #-} module Main where import Data.Proxy class Blah (a :: * -> *) where f :: a b -> b instance forall b . Blah [] where f a = let (_ :: Proxy b) = undefined in head a main :: IO () main = return () }}} When I run this using GHC 7.10.1 and GHC HEAD, I'm getting this warnings: {{{ [1 of 1] Compiling Main ( Main.hs, Main.o ) Main.hs:12:17: warning: Unused quantified type variable ‘b’ In the type ‘forall b. Blah []’ In an instance declaration Main.hs:13:13: warning: This pattern-binding binds no variables: (_ :: Proxy b) = undefined Linking Main ... }}} First warning is wrong. `b` is used, and this program doesn't compile if I remove that `b`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10722> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #3306: Improve syntax for GADT + records
by GHC 03 Aug '15

03 Aug '15

#3306: Improve syntax for GADT + records -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: feature request | Status: closed Priority: normal | Milestone: 6.12.1 Component: Compiler | Version: 6.10.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Changes (by skvadrik): * failure: => None/Unknown Comment: 6 years later: removed deprecated syntax for GADT constuctors. This allows to get rid of 2 reduce/reduce conflicts in parser. Conflicting productions were: {{{ gadt_constr -> con_list '::' sigtype gadt_constr -> oqtycon '{' fielddecls '}' '::' sigtype }}} Recursive inlining of con_list and oqtycon helped reveal the conflict: {{{ gadt_constr -> '(' CONSYM ')' '::' sigtype gadt_constr -> '(' CONSYM ')' '{' fielddecls '}' '::' sigtype }}} between two types of GADT constructors (second form stands for deprecated syntax). However, old syntax allowed `oqtycon` in constructor names, while new syntax allows `con` (which is not the same). There are therefore some constructor names that cannot be expressed in terms of new syntax (e.g. `(*)`). Note that ordinary data constructors are parsed in a different way than GADTs: types and names are mixed, so names have to be parsed as types and then converted to names. In GADTs constructor names and types are separated by `::`, so names can be parsed as just names and not as types. This results in a difference in the set of names allowed in GADT and ordinary constructors. See `Note [Parsing data constructors is hard]` and `Note [Difference in parsing GADT and data constructors]` Differential Revision: https://phabricator.haskell.org/D1118 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/3306#comment:8> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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