Add documentation which explains that `debugPrint` also logs in release mode #141595

ueman · 2024-01-16T09:37:03Z

It's confusing that debugPrint also prints in release mode, given that a lot (most?) other things prefixed with debug don't do anything in release mode. Therefore, this adds some documentation that this is indeed logging in release mode and adds an example how to disable this.

If you had to change anything in the flutter/tests repo, include a link to the migration guide as per the breaking change policy.

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

lukepighetti · 2024-01-16T18:00:20Z

This is a heck of a trap door and I think we should deprecate it or patch it so it only prints in debug or profile mode

goderbauer · 2024-01-16T21:23:01Z

packages/flutter/lib/src/foundation/print.dart

+/// if(kReleaseMode) {
+///   debugPrint = (_, {int? wrapWidth}) {};
+/// }
+/// ```


I suspect that with this code the callsites are not actually tree shaken out and the strings (plus all the machinery to generate those, which could be huge if e.g. runtimeType is used) remains in the release binary.

The better advice to give here is that calls to debugPrint should only happen from a debug context (e.g. from within a if (kDebugMode) { } block or within an assert). In general, that is the convention in the framework: methods starting with debug* should only be invoked from a debug context. debugPrint is no exception there.

I suspect that with this code the callsites are not actually tree shaken out and the strings

Interesting, I wasn't aware of that

Does the avoid_print lint special case this rule? (as-in it should also lint on debugPrint if not used in this way)

I don't think so. The lint rule just checks for print(...)

goderbauer · 2024-01-16T21:24:01Z

packages/flutter/lib/src/foundation/print.dart

@@ -31,6 +31,14 @@ typedef DebugPrintCallback = void Function(String? message, { int? wrapWidth });
 /// Prints a message to the console, which you can access using the "flutter"
 /// tool's "logs" command ("flutter logs").
 ///
+/// `debugPrint` logs to console even in [release mode](https://docs.flutter.dev/testing/build-modes#release).


nit: "Avoid starting a sentence with a lowercase letter.", https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#use-correct-grammar

goderbauer · 2024-01-16T21:24:19Z

packages/flutter/lib/src/foundation/print.dart

+/// `debugPrint` logs to console even in [release mode](https://docs.flutter.dev/testing/build-modes#release).
+/// To disable logging from [debugPrint] in release mode, set it to a no-op:
+/// ```dart
+/// if(kReleaseMode) {


nit: missing space:

Suggested change

/// if(kReleaseMode) {

/// if (kReleaseMode) {

goderbauer

LGTM

gspencergoog

…s in release mode (flutter/flutter#141595)

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…r#5965) flutter/flutter@3ee8ff2...5b673c2 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from fd0335a910b8 to b229878c57f5 (1 revision) (flutter/flutter#142051) 2024-01-23 goderbauer@google.com Remove unused clipBehavior from OverflowBar (flutter/flutter#141976) 2024-01-23 engine-flutter-autoroll@skia.org Roll Packages from e4cbf23 to 841fe90 (7 revisions) (flutter/flutter#142047) 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from d2855da628da to fd0335a910b8 (1 revision) (flutter/flutter#142046) 2024-01-23 leroux_bruno@yahoo.fr Add Share button to the SelectableRegion toolbar on Android (flutter/flutter#141447) 2024-01-23 davidmartos96@gmail.com Relax the warning of unavailable tokens in `gen_defaults` when a default value is provided (flutter/flutter#140872) 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from 37f68f6fc7fc to d2855da628da (1 revision) (flutter/flutter#142033) 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from 9e582c9032e5 to 37f68f6fc7fc (1 revision) (flutter/flutter#142027) 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from df6b15d35703 to 9e582c9032e5 (1 revision) (flutter/flutter#142026) 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from d3dbd4225e08 to df6b15d35703 (6 revisions) (flutter/flutter#142023) 2024-01-23 ian@hixie.ch Add a comment about how to test flutter_goldens (flutter/flutter#141902) 2024-01-23 ian@hixie.ch Enable contextMenuBuilder in the absence of selectionControls (flutter/flutter#141810) 2024-01-23 engine-flutter-autoroll@skia.org Roll Flutter Engine from b069d7f8f1fd to d3dbd4225e08 (3 revisions) (flutter/flutter#142005) 2024-01-23 98614782+auto-submit[bot]@users.noreply.github.com Reverts "hello_world app: migrate to Gradle Kotlin DSL" (flutter/flutter#142018) 2024-01-22 jmccandless@google.com Floating cursor docs (flutter/flutter#133002) 2024-01-22 git@reb0.org refactor: Rename filterPluginsByPlatform, cleanup Platform Strings (flutter/flutter#141780) 2024-01-22 barpac02@gmail.com hello_world app: migrate to Gradle Kotlin DSL (flutter/flutter#141541) 2024-01-22 engine-flutter-autoroll@skia.org Roll Flutter Engine from b2762f410840 to b069d7f8f1fd (4 revisions) (flutter/flutter#141993) 2024-01-22 matanlurey@users.noreply.github.com Remove duplicate code as suggested by natebosch. (flutter/flutter#141988) 2024-01-22 jesus_sguerrero@hotmail.com Revert "Remove hack from PageView." (flutter/flutter#141977) 2024-01-22 engine-flutter-autoroll@skia.org Roll Flutter Engine from d653559ae183 to b2762f410840 (3 revisions) (flutter/flutter#141978) 2024-01-22 matanlurey@users.noreply.github.com Do not hang on test failures of tests within `flutter_tools` (flutter/flutter#141821) 2024-01-22 gspencergoog@users.noreply.github.com Remove unneeded expectation in test (flutter/flutter#141822) 2024-01-22 engine-flutter-autoroll@skia.org Roll Flutter Engine from 1efe8ba6bc04 to d653559ae183 (3 revisions) (flutter/flutter#141972) 2024-01-22 ueman@users.noreply.github.com Add documentation which explains that `debugPrint` also logs in release mode (flutter/flutter#141595) 2024-01-22 tessertaha@gmail.com Fix `RangeSlider` throws a null-check error after `clearSemantics` is called (flutter/flutter#141965) 2024-01-22 engine-flutter-autoroll@skia.org Roll Flutter Engine from c49989292fc1 to 1efe8ba6bc04 (1 revision) (flutter/flutter#141969) 2024-01-22 110993981+htoor3@users.noreply.github.com [web] - Fix broken `TextField` in semantics mode when it's a sibling of `Navigator` (flutter/flutter#138446) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC bmparr@google.com,rmistry@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

github-actions bot added the framework flutter/packages/flutter repository. See also f: labels. label Jan 16, 2024

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ueman added 2 commits January 22, 2024 09:13

Explain that debug print also logs in release mode

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Update documentation

9709121

goderbauer force-pushed the patch-1 branch from 8af0372 to 9709121 Compare January 22, 2024 17:13

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Add documentation which explains that `debugPrint` also logs in release mode #141595

Add documentation which explains that `debugPrint` also logs in release mode #141595

ueman commented Jan 16, 2024 •

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Add documentation which explains that debugPrint also logs in release mode #141595

Add documentation which explains that debugPrint also logs in release mode #141595

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Pre-launch Checklist

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Add documentation which explains that `debugPrint` also logs in release mode #141595

Add documentation which explains that `debugPrint` also logs in release mode #141595

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