Hi Richard, thanks for your questions! I'll answer them below:
> […] and I somehow know (though I forget where I learned it)
You can find a summary of the available linting (with HLint) Hadrian
rules here:
https://gitlab.haskell.org/ghc/ghc/-/wikis/contributing#working-conventions
> I introduced one of these errors, in GHC.Tc.Utils.Unify; the other
errors are in files I have not modified. Will these affect CI?
How old is your latest sync with upstream/master? Maybe these lints have
been corrected after your last pull?
> Hadrian crashes at the end. Is that expected? It says "system command
failed" with a bunch of gobbledegook. Is this an error within Hadrian?
It's Hadrian's way to exit with a non-0 code and give us some info about
what went wrong
> Are these colors configurable?
Not to my knowledge. Until NO_COLOR or more colour schemes are
implemented in HLint, you can use this (sad) workaround:
```
TERM=dumb hadrian/build -j lint:compiler
```
which remove all the colours from the output.
Hope this helps, sorry for the confusion.
Cheers,
Hécate
Le 30/04/2021 à 22:12, Richard Eisenberg a écrit :
Hi devs,
I see in CI that we're now linting the GHC source code. In order to
avoid CI failure, I would like to lint locally, and I somehow know
(though I forget where I learned it) that hadrian/build lint:compiler
is the way to do this. After building hlint, I am able to do this. But
the output is surprising; here is the tail:
# hlint (for lint:compiler)
compiler/GHC/Tc/Utils/Unify.hs:2:1-36: Warning: Unused LANGUAGE pragma
Found:
{-# LANGUAGE MultiWayIf #-}
Perhaps you should remove it.
compiler/stage1/build/GHC/Parser.hs:6:1-29: Warning: Unused LANGUAGE
pragma
Found:
{-# LANGUAGE ViewPatterns #-}
Perhaps you should remove it.
compiler/stage1/build/GHC/Parser.hs:8:1-27: Warning: Unused LANGUAGE
pragma
Found:
{-# LANGUAGE LambdaCase #-}
Perhaps you should remove it.
compiler/stage1/build/GHC/Parser.hs:38:1-54: Warning: Use fewer imports
Found:
import Control.Monad ( unless, liftM, when,(<=<))
import Control.Monad ( ap )
Perhaps:
import Control.Monad ( unless, liftM, when,(<=<), ap )
compiler/stage1/build/GHC/Parser.hs:43:1-18: Warning: Use fewer imports
Found:
import GHC.Prelude
import GHC.Prelude
Perhaps:
import GHC.Prelude
compiler/stage1/build/GHC/Cmm/Parser.hs:17:1-24: Warning: Use fewer
imports
Found:
import GHC.StgToCmm.Prof
import GHC.StgToCmm.Prof
Perhaps:
import GHC.StgToCmm.Prof
compiler/stage1/build/GHC/Cmm/Parser.hs:71:1-20: Warning: Use fewer
imports
Found:
import Control.Monad
import Control.Monad ( ap )
Perhaps:
import Control.Monad
compiler/stage2/build/GHC/Parser.hs:6:1-29: Warning: Unused LANGUAGE
pragma
Found:
{-# LANGUAGE ViewPatterns #-}
Perhaps you should remove it.
compiler/stage2/build/GHC/Parser.hs:8:1-27: Warning: Unused LANGUAGE
pragma
Found:
{-# LANGUAGE LambdaCase #-}
Perhaps you should remove it.
compiler/stage2/build/GHC/Parser.hs:38:1-54: Warning: Use fewer imports
Found:
import Control.Monad ( unless, liftM, when,(<=<))
import Control.Monad ( ap )
Perhaps:
import Control.Monad ( unless, liftM, when,(<=<), ap )
compiler/stage2/build/GHC/Parser.hs:43:1-18: Warning: Use fewer imports
Found:
import GHC.Prelude
import GHC.Prelude
Perhaps:
import GHC.Prelude
compiler/stage2/build/GHC/Cmm/Parser.hs:17:1-24: Warning: Use fewer
imports
Found:
import GHC.StgToCmm.Prof
import GHC.StgToCmm.Prof
Perhaps:
import GHC.StgToCmm.Prof
compiler/stage2/build/GHC/Cmm/Parser.hs:71:1-20: Warning: Use fewer
imports
Found:
import Control.Monad
import Control.Monad ( ap )
Perhaps:
import Control.Monad
13 hints
Error when running Shake build system:
at want, called at src/Main.hs:104:30 in main:Main
* Depends on: lint:compiler
at cmd_, called at src/Rules/Lint.hs:70:3 in main:Rules.Lint
* Raised the exception:
Development.Shake.cmd, system command failed
Command line: hlint -j --cpp-define x86_64_HOST_ARCH
--cpp-include=includes --cpp-include=_build/stage1/lib
--cpp-include=compiler --cpp-include=_build/stage1/lib/ghcplatform.h
--cpp-include=_build/stage1/compiler/build -h compiler/.hlint.yaml
compiler
Exit code: 1
Stderr:
There are several curiosities here:
* I introduced one of these errors, in GHC.Tc.Utils.Unify; the other
errors are in files I have not modified. Will these affect CI?
* Hadrian crashes at the end. Is that expected? It says "system
command failed" with a bunch of gobbledegook. Is this an error within
Hadrian? Or is this just Hadrian's way of saying that it encountered
an error when linting? If it's the latter, the current message is hard
to read.
* As you may be able to see, I use a dark-background terminal window.
The colors output by the hlint process are nigh impossible to read
when describing redundant LANGUAGE pragmas. Are these colors configurable?
Thanks!
Richard
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