With v2 commands being the default, use dist-newstyle.

[philderbeast]

From #8832, bumps the location of the default directory where Cabal puts generated build files to (default dist-newstyle).

$ cabal run cabal -- clean --help
Up to date
Clean the package store and remove temporary files.

Usage: cabal new-clean [FLAGS]

Removes all temporary files created during the building process (.hi, .o,
preprocessed sources, etc.) and also empties out the local caches (by
default).


Flags for clean:
 -h, --help                     Show this help text
 -v, --verbose[=n]              Control verbosity (n is 0--3, default
                                verbosity level is 1)
 --builddir=DIR                 The directory where Cabal puts generated build
                                files (default dist-newstyle)
 --project-dir=DIR              Set the path of the project directory
 --project-file=FILE            Set the path of the cabal.project file
                                (relative to the project directory when
                                relative)
 -s, --save-config              Save configuration, only remove build
                                artifacts

[ulysses4ever]

Thank you!

Just in case, did you check if defaultDistPref is used anywhere besides help messages? If so, the change may have unpredictable consequences. I'm approving because I'm reckless when it comes to breaking backwards compatibilit, but other may be more cautious…

[philderbeast]

I ran the tests locally.

$ cabal run cabal-tests -- --with-cabal=/.../cabal-install-3.9.0.0/x/cabal/build/cabal/cabal
...
456 tests, 8 skipped, 0 unexpected passes, 0 unexpected fails.
OK

I found 15 hits in 7 files for defaultDistPref. This renaming of the dist dir, I was unsure if it is safe:

cabal/cabal-install/src/Distribution/Client/Install.hs

Lines 1274 to 1285 in 0f51816

	-- 'cabal sdist' puts pre-generated files in the 'dist'
	-- directory. This fails when a nonstandard build directory name
	-- is used (as is the case with sandboxes), so we need to rename
	-- the 'dist' dir here.
	--
	-- TODO: 'cabal get happy && cd sandbox && cabal install ../happy' still
	-- fails even with this workaround. We probably can live with that.
	maybeRenameDistDir :: FilePath -> IO ()
	maybeRenameDistDir absUnpackedPath = do
	let distDirPath = absUnpackedPath </> defaultDistPref
	distDirPathTmp = absUnpackedPath </> (defaultDistPref ++ "-tmp")
	distDirPathNew = absUnpackedPath </> distPref

[philderbeast]

I also noticed a hard-coded dist string that I have not changed:

cabal/Cabal/src/Distribution/Simple.hs

Lines 516 to 527 in 0f51816

	clean :: PackageDescription -> CleanFlags -> IO ()
	clean pkg_descr flags = do
	let distPref = fromFlagOrDefault defaultDistPref $ cleanDistPref flags
	notice verbosity "cleaning..."
	maybeConfig <- if fromFlag (cleanSaveConf flags)
	then maybeGetPersistBuildConfig distPref
	else return Nothing
	-- remove the whole dist/ directory rather than tracking exactly what files
	-- we created in there.
	chattyTry "removing dist/" $ do

[philderbeast]

The word or abbreviation "dist" is also used in a few strings that can be found grepping for ".*\s+dist\s+.*".

cabal/Cabal-tests/tests/HackageTests.hs

Lines 369 to 371 in 0f51816

	putStrLn $ show c ++ " build dist suspicious"
	putStrLn $ show d ++ " build dist suspicious warning"
	putStrLn $ show e ++ " build dist inexcusable"

cabal/cabal-testsuite/main/cabal-tests.hs

Line 105 in 0f51816

hPutStrLn stderr $ "Using dist dir: " ++ dist_dir

cabal/Cabal/src/Distribution/Simple/Setup/Install.hs

Line 93 in 0f51816

"install the package in the install subdirectory of the dist prefix, so it can be used without being installed"

[ulysses4ever]

As this touches a rather old dark corner of Cabal, I'd like to summon @gbaz to give this PR a look. Also, @Mikolaj may want to weigh in because our precious contributors deserve the best feedback in the world!

[Mikolaj]

Thank you for the PR. From the PR description alone I can't guess if this changes the behaviour of cabal or only the help text and whether it affects only v2 or also the Setup and v1 API. If it does change the behaviour, could we list the changes with tickboxes and for each discuss the consequences (to correctness and to backward compatibility)?

[Mikolaj]

LGTM. Please feel free to set the "merge_me" label

[Mikolaj]

Uhoh, I've just found #7924. Could we make sure that changes in "multiple files, in separate packages" are not really needed and document here why not?

[mpickering]

I am not sure whether this is the right fix or not (I err towards not). As @Mikolaj points out this affects the v1- and ./Setup API so now the default location for those commands will also be dist-newstyle.

See the comments on the thread