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ghc-mod takes a very long time to check a module using template haskell in a project depending on haskell-src-exts #950

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expipiplus1 opened this issue Apr 19, 2019 · 1 comment
Open

ghc-mod takes a very long time to check a module using template haskell in a project depending on haskell-src-exts #950

expipiplus1 opened this issue Apr 19, 2019 · 1 comment

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@expipiplus1
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expipiplus1 commented Apr 19, 2019 •
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Summary

In a project using haskell-src-exts as a transitive dependency ghc mod hangs 100% cpu usage when loading a file with quasi quotes or template haskell. On my machine this takes about

I have not tested with other large packages as dependencies.

To reproduce:

  • Main.hs
{-# language QuasiQuotes #-}

module Main where

main :: IO ()
main = pure 1
  • ghc-mod-test.cabal
name:           ghc-mod-test
version:        0.0.0
build-type:     Simple

executable ghc-mod-test
  main-is: Main.hs
  build-depends:
      base
    , haskell-src-exts

  • Run ghc-mod browse Main.hs --verbose 7

  • Observe that ghc-mod hangs after printing Target needs interpeter, switching to LinkInMemory/HscInterpreted. Perfectly normal if anything is using TemplateHaskell, QuasiQuotes or PatternSynonyms.

  • Remove the haskell-src-exts line from ghc-mod-test.cabal

  • Run ghc-mod browse Main.hs --verbose 7

  • Observe that ghc-mod no longer hangs and correctly identifies the type error in Main.hs

Versions

 $ ghc-pkg list
/nix/store/ynmnlayvwy7rcgqjgdqkik5cwnw4n8pg-ghc-8.6.4-with-packages/lib/ghc-8.6.4/package.conf.d
    Cabal-2.4.0.1
    array-0.5.3.0
    base-4.12.0.0
    binary-0.8.6.0
    bytestring-0.10.8.2
    containers-0.6.0.1
    deepseq-1.4.4.0
    directory-1.3.3.0
    filepath-1.4.2.1
    ghc-8.6.4
    ghc-boot-8.6.4
    ghc-boot-th-8.6.4
    ghc-compact-0.1.0.0
    ghc-heap-8.6.4
    ghc-prim-0.5.3
    ghci-8.6.4
    haskeline-0.7.4.3
    haskell-src-exts-1.20.3
    hpc-0.6.0.3
    integer-gmp-1.0.2.0
    libiserv-8.6.3
    mtl-2.2.2
    parsec-3.1.13.0
    pretty-1.1.3.6
    process-1.6.5.0
    rts-1.0
    stm-2.5.0.0
    template-haskell-2.14.0.0
    terminfo-0.4.1.2
    text-1.2.3.1
    time-1.8.0.2
    transformers-0.5.6.2
    unix-2.7.2.2
    xhtml-3000.2.2.1

$ ghc-mod --version
ghc-mod version 5.9.0.0 compiled by GHC 8.6.4

d96119645c12905858468a98429f6a887330e7d9

ghc-mod's log:

info: Found Cabal project at: /home/j/projects/ghc-mod-test
info: Using Cabal project at: /home/j/projects/ghc-mod-test
DEBUG: setup configuration is out of date
DEBUG: reconfiguring Cabal project
Warning: The configure command is a part of the legacy v1 style of cabal
usage.

Please switch to using either the new project style and the new-configure
command or the legacy v1-configure alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

For more information, see: https://wiki.haskell.org/Cabal/NewBuild

Warning: ghc-mod-test.cabal:0:0: A package using section syntax must specify
at least
'cabal-version: >= 1.2'.
Warning: ghc-mod-test.cabal:0:0: A package using section syntax must specify
at least
'cabal-version: >= 1.2'.
DEBUG: reading cache: /home/j/projects/ghc-mod-test/dist/setup-config.ghc-mod.package-options
DEBUG: regenerating cache: /home/j/projects/ghc-mod-test/dist/setup-config.ghc-mod.package-options (input data changed)
DEBUG: writing memory cache: /home/j/projects/ghc-mod-test/dist/setup-config.ghc-mod.package-options
DEBUG: reading cache: /home/j/projects/ghc-mod-test/dist/setup-config.ghc-mod.cabal-components
DEBUG: regenerating cache: /home/j/projects/ghc-mod-test/dist/setup-config.ghc-mod.cabal-components (input data changed)
DEBUG: writing memory cache: /home/j/projects/ghc-mod-test/dist/setup-config.ghc-mod.cabal-components
DEBUG: resolveEntrypoint:
       ["-i","-idist/build/ghc-mod-test/ghc-mod-test-tmp","-i.","-idist/build/ghc-mod-test/autogen","-idist/build/global-autogen","-Idist/build/ghc-mod-test/autogen","-Idist/build/global-autogen","-Idist/build/ghc-mod-test/ghc-mod-test-tmp","-optP-include","-optPdist/build/ghc-mod-test/autogen/cabal_macros.h"]
DEBUG: resolveEntrypoint: []
DEBUG: making sure autogen files exist
DEBUG: autogen files out of sync
DEBUG: writing Cabal autogen files
DEBUG: reading cache: dist/setup-config.ghc-mod.resolved-components
DEBUG: resolvedComponentsCache: files changed: none
DEBUG: resolveGmComponent:
       ["-optP-include","-optPdist/build/autogen/cabal_macros.h"]
DEBUG: resolveGmComponent:
       ["-i","-idist/build/ghc-mod-test/ghc-mod-test-tmp","-i.","-idist/build/ghc-mod-test/autogen","-idist/build/global-autogen","-Idist/build/ghc-mod-test/autogen","-Idist/build/global-autogen","-Idist/build/ghc-mod-test/ghc-mod-test-tmp","-optP-include","-optPdist/build/ghc-mod-test/autogen/cabal_macros.h","-XHaskell98","-optP-include","-optPdist/build/autogen/cabal_macros.h"]
DEBUG: regenerating cache: dist/setup-config.ghc-mod.resolved-components (input data changed)
DEBUG: writing memory cache: dist/setup-config.ghc-mod.resolved-components
DEBUG: Could not find a component assignment, falling back to
       picking library component in cabal file.
VOMIT: hide all packages(ignore .ghc.environment):: DontLoadGhcEnvironment
VOMIT: Using the following mapped files:
VOMIT: Using the following mapped files:
VOMIT: Initializing GHC session with following options: "-fbuilding-cabal-package" "-O" "-outputdir" "dist/build/ghc-mod-test/ghc-mod-test-tmp" "-odir" "dist/build/ghc-mod-test/ghc-mod-test-tmp" "-hidir" "dist/build/ghc-mod-test/ghc-mod-test-tmp" "-stubdir" "dist/build/ghc-mod-test/ghc-mod-test-tmp" "-i" "-idist/build/ghc-mod-test/ghc-mod-test-tmp" "-i." "-idist/build/ghc-mod-test/autogen" "-idist/build/global-autogen" "-Idist/build/ghc-mod-test/autogen" "-Idist/build/global-autogen" "-Idist/build/ghc-mod-test/ghc-mod-test-tmp" "-optP-include" "-optPdist/build/ghc-mod-test/autogen/cabal_macros.h" "-hide-all-packages" "-Wmissing-home-modules" "-package-id" "base-4.12.0.0" "-package-id" "haskell-src-exts-1.20.3-2fryh11Yuz7lCtLeeIQn8" "-XHaskell98" "-Wno-missing-home-modules" "-O0" "-fno-warn-missing-home-modules"
DEBUG: initSession: Session not initialized, creating new one
VOMIT: Using the following targets: "Main.hs"
DEBUG: loadTargets: Loading: Main.hs
DEBUG: loadTargets: filterModSums: False
info: loadTargets:
      Target needs interpeter, switching to LinkInMemory/HscInterpreted. Perfectly normal if anything is using TemplateHaskell, QuasiQuotes or PatternSynonyms.
<<<LONG WAIT>>>

Main.hs:6:13: error:
    • No instance for (Num ()) arising from the literal ‘1’
    • In the first argument of ‘pure’, namely ‘1’
      In the expression: pure 1
      In an equation for ‘main’: main = pure 1
DEBUG: loadTargets: Loading done
EXCEPTION: browse:
           Could not find module ‘Main.hs’
           Use -v to see a list of the files searched for.
/nix/store/wqrayxv60mxhyw5zmx0hhgj62qz3id58-ghc-mod-5.9.0.0/bin/ghc-mod brows  189.70s user 0.35s system 100% cpu 3:10.00 total
@expipiplus1 expipiplus1 changed the title ghc-mod hangs when using template haskell in a project depending on haskell-src-exts ghc-mod takes a very long time to check a module using template haskell in a project depending on haskell-src-exts Apr 19, 2019
@expipiplus1
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I get the same behavior with GHC-8.4.4 and GHC-8.2.2

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