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clang-tidy: Added an environment variable that allows fix to print the generated diff. #37024

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clang-tidy: Added an environment variable that allows fix to print the generated diff. #37024

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22 changes: 21 additions & 1 deletion ci/lint.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,15 @@ DART="${DART_BIN}/dart"
# to have this as an error.
MAC_HOST_WARNINGS_AS_ERRORS="performance-move-const-arg,performance-unnecessary-value-param"

# FLUTTER_LINT_PRINT_FIX will make it so that fix is executed and the generated
# diff is printed to stdout if clang-tidy fails. This is helpful for enabling
# new lints.
if [[ -z "${FLUTTER_LINT_PRINT_FIX}" ]]; then
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Instead of using an environment variable, I think it would be simpler to just test for the presence of --fix in $@.

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I did that at first, but that makes it hard to use with the bots since $@ is changed in the bot configuration. This way you can just edit lint.sh file temporarily with FLUTTER_LINT_PRINT_FIX=1

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Oh, okay, I get it (I think). So the workflow is to modify the script on a PR branch to get the presubmit checks to generate the diff?

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Yep, that's the best I could come up with for now. Alternatively we could always execute with --fix but I worry about execution time.

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Ideally, we'd have something like flutter/flutter#114085, to pass the --fix flag only in presubmit. In the meantime, I think this change is okay. Would you mind adding a TODO in the code for me that links to that issue?

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We definitely care about postsubmit cycle time.

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Sure, I wouldn't say they have equal weight though. Given that if there is a failure, turning this on and running again takes ~1hr to get results, it might be worth running it always. So the calculus as-to wether this should be turned on always or not should be: (likelihood of violation * 1hr) - ((1 - likelihood of violation) * 5min).

Let me run some tests locally since that 5 minute I just pulled out of my butt. Maybe it isn't so bad to always have it on. Also, maybe the real solution to performance isn't turning off something that is helpful and saves time but to do better sharding. I discuss this in the post-mortem I just sent. Now that I talk about this I think it's better to having this turn on always, assuming it doesn't add a crazy amount of time. I'll measure it.

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I just ran it locally with a diff that was checking 47 files, there was a 12.5% increase in execution time so ~7.5 minutes longer to execute for one that takes ~1 hr.

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Okay, here is my suggestion:

  1. We add a new builder that runs only in pre-submit.
  2. It passes the --fix flag
  3. It only runs when .clang-tidy or engine tree source files have changed.

The new builder definition (one example) would looks something like this: #37082

The missing piece is a new parameter to the engine_lint.py recipe to trigger the logic in this PR around the --fix flag, which would go here:

https://flutter.googlesource.com/recipes/+/refs/heads/main/recipes/engine/engine_lint.proto#8

and here

https://flutter.googlesource.com/recipes/+/refs/heads/main/recipes/engine/engine_lint.py#55

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I think we should land this as is for now. This was helpful for me for now. Let's see about turning it on by default if we get feedback from the team that addressing the lints across multiple platforms is a pain. In normal usage this might not be a big deal and more for when migrating new lint flags. Once we land sharding we'll have some more breathing room to do the fix if we want since it is reducing the number of files linted from ~800 to ~600 that should still leave us ahead.

fix_flag=""
else
fix_flag="--fix"
fi

COMPILE_COMMANDS="$SRC_DIR/out/host_debug/compile_commands.json"
if [ ! -f "$COMPILE_COMMANDS" ]; then
(cd "$SRC_DIR"; ./flutter/tools/gn)
Expand All @@ -47,7 +56,18 @@ cd "$SCRIPT_DIR"
"$SRC_DIR/flutter/tools/clang_tidy/bin/main.dart" \
--src-dir="$SRC_DIR" \
--mac-host-warnings-as-errors="$MAC_HOST_WARNINGS_AS_ERRORS" \
"$@"
$fix_flag \
"$@" && true # errors ignored
clang_tidy_return=$?
if [ $clang_tidy_return -ne 0 ]; then
if [ -n "$fix_flag" ]; then
echo "###################################################"
echo "# Attempted to fix issues with the following patch:"
echo "###################################################"
git --no-pager diff
fi
exit $clang_tidy_return
fi

cd "$FLUTTER_DIR"
pylint-2.7 --rcfile=.pylintrc \
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