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[GHC] #11358: GHC generics has differing conFixity behavior between 7.10.3 and 8.1
by GHC 10 Jan '16

10 Jan '16

#11358: GHC generics has differing conFixity behavior between 7.10.3 and 8.1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: RyanGlScott Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.1 (CodeGen) | Keywords: Generics | Operating System: Unknown/Multiple Architecture: | Type of failure: Incorrect result Unknown/Multiple | at runtime Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Compile the following program with GHC 7.10.3 and 8.1: {{{#!hs {-# LANGUAGE DefaultSignatures #-} {-# LANGUAGE DeriveGeneric #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} module Main (main) where import GHC.Generics infixr 1 `T` data T a = T a a deriving Generic instance HasFixity (T a) data I a = a `I` a deriving Generic instance HasFixity (I a) class HasFixity a where fixity :: a -> Fixity default fixity :: (Generic a, GHasFixity (Rep a)) => a -> Fixity fixity = gfixity . from class GHasFixity f where gfixity :: f a -> Fixity instance GHasFixity f => GHasFixity (D1 d f) where gfixity (M1 x) = gfixity x instance Constructor c => GHasFixity (C1 c f) where gfixity c = conFixity c main :: IO () main = do putStrLn $ show (fixity (T "a" "b")) ++ ", " ++ show (fixity ("a" `I` "b")) }}} On GHC 7.10.3, it yields `Prefix, Infix LeftAssociative 9`, but on GHC 8.1, it yields `Infix RightAssociative 1, Prefix`. Why? The implementation of `deriving Generic(1)` changed slightly in GHC 8.1. Before, it would only assign a fixity of `Infix` if a constructor was ''declared'' infix. But GHC 8.1 no longer checks for this—it first checks if there is a user- supplied fixity declaration, and if so, uses that as the `Fixity`. Otherwise, it defaults to `Prefix`, even if the datatype was declared infix! The design of `Fixity` perhaps leaves something to be desired, but at the very least, we should ensure nothing `Fixity`-related breaks for now. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11358> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10337: One-shot module loops have hard to understand messages
by GHC 10 Jan '16

10 Jan '16

#10337: One-shot module loops have hard to understand messages -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Consider these two modules: {{{ -- A.hs module A where -- B.hs module B where import A }}} `ghc --make B.hs` will compile this fine. Now edit `A.hs` to be circular: {{{ -- A.hs module A where import B }}} and attempt to one-shot compile it with `ghc -c A.hs`. You will now get an uninformative error message: {{{ A.hs:1:1: Circular imports: module `A' depends on itself }}} You can get a more informative message with `--make`: {{{ Module imports form a cycle: module `A' (A.hs) imports `B' (./B.hs) which imports `A' (A.hs) }}} We should either suggest users try again with `--make`, or try harder to give a useful message in one-shot mode. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10337> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2940: Do CSE after CorePrep
by GHC 09 Jan '16

09 Jan '16

#2940: Do CSE after CorePrep -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: bug | Status: new Priority: lowest | Milestone: 8.0.1 Component: Compiler | Version: 6.10.1 Resolution: | 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: | -------------------------------------+------------------------------------- Comment (by osa1): Simon, may I ask why you're inclined to think that it'd be better to do CSE earlier not later? Is it because of type safety reasons? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2940#comment:22> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2168: ghci should show haddock comments for identifier
by GHC 09 Jan '16

09 Jan '16

#2168: ghci should show haddock comments for identifier -------------------------------------+------------------------------------- Reporter: j.waldmann | Owner: Type: feature request | Status: new Priority: normal | Milestone: 8.0.1 Component: GHCi | Version: 6.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by alanz): * cc: alanz (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2168#comment:23> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10362: Make tuple constraints into a class
by GHC 09 Jan '16

09 Jan '16

#10362: Make tuple constraints into a class -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- At the moment GHC treats tuple constraints specially. If you grep for `TuplePred` you'll see this. But the special treatment is strange; see the confusion between constraint tuples and ordinary tuples in #9858. But I now realise that we can sweep away all this nonsense. Suppose we declare {{{ module GHC.Classes where class (c1, c2) => (,) c1 c2 instance (c1, c2) => (,) c1 c2 class (c1, c2, c3) => (,) c1 c2 c3 instance (c1, c2, c3) => (,) c1 c2 c3 }}} and so on. (This is analogous the tuple data type declarations in `GHC.Tuple`.) Notice that: * `GHC.Classes,(,)` is a class, of kind `Constraint -> Constraint -> Constraint`. quite distinct from `GHC.Tuple.(,)`, whose kind is `* -> * -> *`. * `GHC.Classes.(,)` is a perfectly ordinary class, with no methods and two superclasses. * So all the usual superclass stuff applies. * If you have a given `Ord a` then you have a given `Eq a` (its superclass). Similarly if you have a given `(,) c1 c2` then you also have given `c1` and `given `c2`. * If you want to construct a dictionary of type `Ord a` (a "wanted"), you must supply a dictionary of type `Eq a`. Similarly, if you want to construct a dictionary of type `(,) c1 c2` then you must supply `c1` and `c2`. * I have written `(,) c1 c2` to stress that there is a class `GHC.Classes.(,)`, but we'll also allow the concrete syntax `(c1,c2)` instead. * Nevertheless the syntactic form `(c1, c2) => blah` is just sugar for `c1 => c2 => blah` (a type with two, curried constraints); it does not stand a type with a single constraint. Otherwise the instance {{{ instance (c1,c2) => (c1,c2) }}} would be the identity function! The key thing is that, aside from special syntax, `(,)` is a perfectly ordinary class, so we can simply delete all the special treatment of `TuplePred`. (Implicit parameters are also treated as a special class, incidentally.) There should be no user-visible effects. But I think it would cure the worst aspects of #10359, as well as cleaning up `TypeRep` confusion. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10362> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11281: Way to run --make and -M simultaneously
by GHC 08 Jan '16

08 Jan '16

#11281: Way to run --make and -M simultaneously -------------------------------------+------------------------------------- Reporter: ezyang | Owner: Type: feature | Status: new request | 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 Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In some cases, users would like to build their projects `--make` and also print out dependency information `-M` (so that they can sanity check file lists, etc.) It shouldn't be too difficult to arrange for `--make` and `-M file` to mean, put the Makefile information in `file`. Cabal's request: https://github.com/haskell/cabal/issues/2982 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11281> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7414: plugins always trigger recompilation
by GHC 08 Jan '16

08 Jan '16

#7414: plugins always trigger recompilation -------------------------------------+------------------------------------- Reporter: jwlato | Owner: Type: feature request | Status: new Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: plugin, | recompilation Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by ezyang): Related #7277, which has the opposite problem where rely only on the interface hash (and not an "implementation" hash.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7414#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7277: Recompilation check fails for TH unless functions are inlined
by GHC 08 Jan '16

08 Jan '16

#7277: Recompilation check fails for TH unless functions are inlined -------------------------------------+------------------------------------- Reporter: orenbenkiki | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.1 Component: Template Haskell | Version: 7.4.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: 481 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by ezyang): Related #7414, which is the opposite problem but for plugins: we ALWAYS recompile, even when the implementation is the same. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7277#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #9009: Confusing error message when loading package with TH
by GHC 08 Jan '16

08 Jan '16

#9009: Confusing error message when loading package with TH ------------------------------------+------------------------------------- Reporter: jstolarek | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Package system | Version: 7.8.2 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: Other Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- I got this error message when compiling a file that calls Template Haskell function from `singletons` package: {{{ [1 of 1] Compiling Splices ( Splices.hs, Splices.o ) Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package transformers-0.3.0.0 ... linking ... done. Loading package pretty-1.1.1.1 ... linking ... done. Loading package array-0.5.0.0 ... linking ... done. Loading package deepseq-1.3.0.2 ... linking ... done. Loading package containers-0.5.5.1 ... linking ... done. Loading package mtl-2.1.2 ... linking ... done. Loading package template-haskell ... linking ... done. Loading package syb-0.4.1 ... linking ... done. Loading package th-desugar-1.4.0 ... linking ... done. Loading package singletons-1.0 ... <command line>: can't load .so/.DLL for: /home/killy/.cabal/lib/x86_64-linux- ghc-7.8.2/singletons-1.0/libHSsingletons-1.0-ghc7.8.2.so (/home/killy/.cabal/lib/x86_64-linux- ghc-7.8.2/singletons-1.0/libHSsingletons-1.0-ghc7.8.2.so: undefined symbol: singletonszm1zi0_DataziSingletonsziSingleziMonad_lookupProxy1_info) }}} After some investigation it turned out that the module Data.Singletons.Single.Monad was not listed in singletons.cabal file - neither under exported-modules nor other-modules - when the package was installed. The error message is mostly confusing. It would be good to at least get a hint on the possible cause. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9009> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #8060: Undefined symbols when using Template Haskell linked from another object with unexposed modules
by GHC 08 Jan '16

08 Jan '16

#8060: Undefined symbols when using Template Haskell linked from another object with unexposed modules -----------------------------------+--------------------------------------- Reporter: tvynr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: | Type of failure: Compile-time crash Unknown/Multiple | Test Case: Difficulty: Unknown | Blocking: Blocked By: | Related Tickets: | -----------------------------------+--------------------------------------- I have constructed two Cabal projects named "first" and "second". The "first" project defines three files: Logging.hs (which provides some basic logging functionality) and FirstExample.hs and FirstDependent.hs (the latter of which imports the former). In the cabal file, only Logging and FirstDependent are exposed modules. FirstDependent uses a Template Haskell function "loggingFunctions" which defines logging functions for that module. Using cabal or cabal-dev to build this package works quite nicely. The second project depends on the first project and contains a single file, Second.hs. This file imports Logging but neither of the other two files. It also uses the loggingFunctions routine to generate local logging functions. The presence of the "$(loggingFunctions)" splice in Second.hs makes the problem visible, but the real problem is in the first project. Upon compilation of the "second" project with cabal or cabal- dev, the following error is generated: {{{ cabal-dev -s ../cabal-dev-sandbox --with-cabal-install=cabal configure Resolving dependencies... Configuring second-0.1... cabal-dev -s ../cabal-dev-sandbox --with-cabal-install=cabal build Building second-0.1... Preprocessing library second-0.1... [1 of 1] Compiling Second ( lib-src/Second.hs, dist/build/Second.o ) Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package array-0.4.0.1 ... linking ... done. Loading package deepseq-1.3.0.1 ... linking ... done. Loading package containers-0.5.0.0 ... linking ... done. Loading package filepath-1.3.0.1 ... linking ... done. Loading package old-locale-1.0.0.5 ... linking ... done. Loading package time-1.4.0.1 ... linking ... done. Loading package bytestring-0.10.0.2 ... linking ... done. Loading package unix-2.6.0.1 ... linking ... done. Loading package directory-1.2.0.1 ... linking ... done. Loading package transformers-0.3.0.0 ... linking ... done. Loading package mtl-2.1.2 ... linking ... done. Loading package text-0.11.3.1 ... linking ... done. Loading package parsec-3.1.3 ... linking ... done. Loading package network-2.4.1.2 ... linking ... done. Loading package process-1.1.0.2 ... linking ... done. Loading package hslogger-1.2.1 ... linking ... done. Loading package pretty-1.1.1.0 ... linking ... done. Loading package template-haskell ... linking ... done. Loading package first-0.2 ... linking ... ghc: /home/some- directories/example/first/../cabal-dev- sandbox//lib/first-0.2/ghc-7.6.1.20121207/HSfirst-0.2.o: unknown symbol `firstzm0zi2_FirstExample_zdfShowErrorSpec3_closure' ghc: unable to load package `first-0.2' make[1]: *** [build] Error 1 }}} Upon further investigation, it would seem that the .o file constructed to represent the "first" project has not been completely constructed: {{{ $ objdump -t cabal-dev- sandbox/lib/first-0.2/ghc-7.6.1.20121207/HSfirst-0.2.o | grep '\*UND\*' | grep first 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfOrdErrorSpeczuzdczg_info 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfShowErrorSpec3_closure 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfOrdErrorSpeczuzdczl_info 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfEqErrorSpeczuzdczeze_info 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfOrdErrorSpeczuzdczlze_info 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfOrdErrorSpeczuzdccompare_info 00000000 *UND* 00000000 firstzm0zi2_FirstExample_zdfOrdErrorSpeczuzdczgze_info }}} (While the above dump is for ghc 7.6.1, this has also been tested on ghc 7.6.3 as well as on both i386- and amd64-based OS installs.) If the "$(loggingFunctions)" splice is removed from Second.hs, then the project builds (presumably because the logic used by non-Template Haskell projects for linking differs from that of Template Haskell projects). Fortunately, it seems that exposing every module of the "first" project resolves this issue. But please note that the FirstExample.hs and FirstDependent.hs files are completely unrelated to the Second.hs file; the latter does not depend on the former in any way. It seems strange that I can't use Template Haskell across projects without exposing all of my project modules. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8060> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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