We have zero-line text files that aren't empty

[philderbeast]

Describe the bug
Investigating #9798, I wanted to find the number of single line project files. In doing this I found some were reported as having 0 lines.

On review, @geekosaur is catching the mistake I'm often making of dropping or forgetting these newlines.

Therefore, “lines” not ending in a newline character aren't considered actual lines. That's why some programs have problems processing the last line of a file if it isn't newline terminated.

The advantage of following this convention is that all POSIX tools expect and use it.
SOURCE: Why should text files end with a newline?

I have a script to add newlines when missing and can use it to fix up some files that don't conform, for instance *.hs and *.project files. I didn't find any non-conforming *.cabal files. There are only two legitimate zero line (empty) projects;

• ./cabal-install/tests/fixtures/project-root/cabal.project
• ./cabal-install/tests/fixtures/project-root/nix/cabal.project

To Reproduce

$ find -name '*.project' -exec wc -l {} \; | sort -k 1
0 ./cabal-install/tests/fixtures/project-root/cabal.project
0 ./cabal-install/tests/fixtures/project-root/nix/cabal.project
0 ./cabal-testsuite/PackageTests/ExtraProgPath/cabal.project
0 ./cabal-testsuite/PackageTests/HaddockArgs/cabal.project
0 ./cabal-testsuite/PackageTests/HaddockWarn/cabal.project
0 ./cabal-testsuite/PackageTests/NewBuild/CmdRun/Script/cabal.project
0 ./cabal-testsuite/PackageTests/NewBuild/CmdRun/ScriptLiterate/cabal.project
0 ./cabal-testsuite/PackageTests/NewHaddock/Fails/cabal.project
0 ./cabal-testsuite/PackageTests/NewSdist/DeterministicTrivial/cabal.project
0 ./cabal-testsuite/PackageTests/PkgConfigParse/cabal.project
0 ./cabal-testsuite/PackageTests/Regression/T5782Diamond/cabal.project
0 ./cabal-testsuite/PackageTests/SDist/Respect-Project-File/cabal.project
0 ./cabal-testsuite/PackageTests/SDist/T5195and5349/cabal.project
0 ./cabal-testsuite/PackageTests/WarnEarlyOverwrite/cabal.project
...

$ cat ./cabal-testsuite/PackageTests/WarnEarlyOverwrite/cabal.project
packages: .⏎

Expected behavior
We add the missing newlines (I have a script for this).

#!/bin/bash
# SEE: https://unix.stackexchange.com/questions/31947/how-to-add-a-newline-to-the-end-of-a-file
for f in $(git grep -Il '' -- "$1"); do
    echo "$f";
    tail -c1 < "$f" | read -r _ || echo >> "$f";
done

Stretch goal: We stop relying on @geekosaur spotting these mistakes and add a check for this in CI.

[ffaf1]

Mhhh I thought we already did it re: automating this bit of geekosaur

cabal/fix-whitespace.yaml

Lines 1 to 6 in 74b1f21

	# This file contains the project-specific settings for `fix-whitespace` a tiny
	# but useful tool to
	#
	# * Removes trailing whitespace.
	# * Removes trailing lines containing nothing but whitespace.
	# * Ensures that the file ends in a newline character.

[philderbeast]

Looking at the blame for fix-whitespace.yaml, I see it was added along with .github/workflows/whitespace.yml in #8320. That workflow no longer exists and I can't find another one that still runs this check, that runs fix-whitespace --check.

[philderbeast]

With fix-whitespace we have these violations;

$ fix-whitespace --version
0.1

$ fix-whitespace --check
[ Violation detected ] .github/workflows/bootstrap.skip.yml
[ Violation detected ] .github/workflows/validate.skip.yml
[ Violation detected ] .github/workflows/validate.yml
[ Violation detected ] CONTRIBUTING.md
[ Violation detected ] Cabal-described/src/Distribution/Described.hs
[ Violation detected ] Cabal-described/src/Distribution/Utils/CharSet.hs
[ Violation detected ] Cabal-tests/tests/UnitTests/Distribution/Simple/Program/GHC.hs
[ Violation detected ] README.md
[ Violation detected ] bootstrap/src/Main.hs
[ Violation detected ] cabal-install/tests/IntegrationTests2/.gitignore
[ Violation detected ] cabal-install-solver/src/Distribution/Solver/Modular/Message.hs
[ Violation detected ] cabal-testsuite/PackageTests/Backpack/Includes2/setup-per-component.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/CmmSourcesExe/cmmexperiment.cabal
[ Violation detected ] cabal-testsuite/PackageTests/ExternalCommandSetup/setup.cabal.hs
[ Violation detected ] cabal-testsuite/PackageTests/NewBuild/CmdRepl/CustomSetup/foo/Setup.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.dot-uv.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.dot-uv.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.ignore-project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.ignore-project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.no-project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.no-project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.sub-pq.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.sub-pq.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.sub-rs.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-No/cabal.sub-rs.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.dot-uv.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.dot-uv.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.ignore-project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.ignore-project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.no-project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.no-project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.sub-pq.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.sub-pq.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.sub-rs.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/Projects-Default-Yes/cabal.sub-rs.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/README.md
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/cabal.ignore-project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/cabal.ignore-project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/cabal.no-project.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/SDist/Respect-Project-File/cabal.no-project.v2.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/VersionPriority/0-local.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/VersionPriority/1-local.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/VersionPriority/2-local.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/WarnEarlyOverwrite/clean-install-by-copy.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/WarnEarlyOverwrite/clean-install-by-symlink.test.hs
[ Violation detected ] cabal-testsuite/PackageTests/WarnEarlyOverwrite/dirty-install.test.hs
[ Violation detected ] doc/buildinfo-fields-reference.rst
[ Violation detected ] doc/cabal-commands.rst
[ Violation detected ] doc/getting-started.rst
[ Violation detected ] fourmolu.yaml

[philderbeast]

The configuration doesn't include cabal.project files;

cabal/fix-whitespace.yaml

Line 43 in aaf16c4

- "cabal.project.*"

[philderbeast]

I find our naming for project files odd in that it doesn't have a consistent file extension, .project. Elsewhere I've used cabal.something.project rather than what we use here, cabal.project.something.

[philderbeast]

@Kleidukos was there some bad interaction between fourmolu and fix-whitespace? The former doesn't cover all the file types of the later so perhaps we could revive some of fix-whitespace, deleted in 827ee18.

$ git log -p -- .github/workflows/whitespace.yml
commit 827ee18e0864d9774eb2f4d687e2eca69a61d478
Date:   Wed May 24 09:34:10 2023 +0200

    Formatting configuration

diff --git a/.github/workflows/whitespace.yml b/.github/workflows/whitespace.yml
deleted file mode 100644
index 1254f7ccc..000000000

[ulysses4ever]

I think we should put back the action running fix-whitespace and revise the tool's config to include more files and to print explanation for violations (it's a new flag in fix-whitespace), and maybe something else.