Fragment 1.7.0 crashes when used with predictive back gesture and Navigation [342419080]

Fixed

Bug

Status Update

No update yet.

Description

fo...@gmail.com

created issue #1

May 24, 2024 10:41AM

Component used: Fragment, Navigation

Version used: Fragment 1.7.0, Navigation 2.7.7

Devices/Android versions reproduced on: Poco F5, Android 14

Screen recording demonstrating the issue and sample project are attached. Predictive back gesture is enabled.

Steps to reproduce: Navigate to another tab. Perform the back gesture and cancel it. Navigate to another tab.

Exception:

java.lang.IllegalArgumentException: saveBackStack("e50c3dd6-64e7-4d9f-bece-08694e6ecd62") must be self contained and not reference fragments from non-saved FragmentTransactions. Found reference to fragment HomeFragment{6ef3f53} (67314589-819b-4ead-955d-6fc8e1f8cb38 id=0x7f080132 tag=ee78b252-f193-4d4e-8e35-b6ad24766bf7) in BackStackEntry{4a78e9d #1 e50c3dd6-64e7-4d9f-bece-08694e6ecd62} that were previously added to the FragmentManager through a separate FragmentTransaction.
	at androidx.fragment.app.FragmentManager.saveBackStackState(FragmentManager.java:2389)
	at androidx.fragment.app.FragmentManager$SaveBackStackState.generateOps(FragmentManager.java:3715)
	at androidx.fragment.app.FragmentManager.generateOpsForPendingActions(FragmentManager.java:2271)
	at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1938)
	at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:661)
	at android.os.Handler.handleCallback(Handler.java:958)
	at android.os.Handler.dispatchMessage(Handler.java:99)
	at android.os.Looper.loopOnce(Looper.java:224)
	at android.os.Looper.loop(Looper.java:318)
	at android.app.ActivityThread.main(ActivityThread.java:8759)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:561)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1013)

Screenrecorder-2024-05-24-15-34-23-785.mp4

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FragmentNavigation.zip

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Comments

fo...@gmail.com <fo...@gmail.com> #2May 27, 2024 05:28AM

Hi Ed, Thank you so much for these suggestions. I've been reviewing them and merging them in. Hopefully it should be live. I've included a thank you note too in the article.

jb...@google.com <jb...@google.com> Jul 8, 2024 03:19PM

Assigned to jb...@google.com.

th...@outlook.com <th...@outlook.com> #3Oct 4, 2024 07:56AM

Great! Thanks a lot, I'll look for the live updates soon!

pa...@gmail.com <pa...@gmail.com> #4Oct 7, 2024 07:09AM

Hello, do we have any news on the status of this?

il...@google.com <il...@google.com> Oct 9, 2024 11:27PM

Reassigned to il...@google.com.

ap...@google.com <ap...@google.com> #5Oct 21, 2024 09:42PM

Project: platform/frameworks/support
Branch: androidx-main
Author: Ian Lake <ilake@google.com>
Link: https://android-review.googlesource.com/3315453

Prevent double expansion of transaction operations

Expand for full commit details

Prevent double expansion of transaction operations

How predictive back with fragments works is that
we pop the FragmentTransaction from the
FragmentManager, but keep a copy of that
transaction around in case the back operation
is cancelled (either via gesture or interruption
by changes to the FragmentManager).

In the cancellation case, we then re-apply the
same FragmentTransaction again, putting the
FragmentManager back into the state it was in
before the predictive back happened.

However, when using operations that are
'expanded' like setPrimaryNavigationFragment(),
we need to explicitly call collapseOps() before
re-executing the operation so that we ensure
that these transactions never have a direct
reference to fragments from other transactions.

By ensuring we only don't double expandOps(),
we can avoid cases where FragmentManager does not
allow references to previous fragments such as when
using saveBackStack().

Relnote: "Fixed an `IllegalStateException` triggered
by `saveBackStack` only after a Predictive Back gesture
was cancelled or interrupted."
Test: new PredictiveBackTest test cases
BUG: 342419080

Change-Id: I3387d9d02495112f211448d7f3c9f862299da697

Files:

M fragment/fragment/src/androidTest/java/androidx/fragment/app/PredictiveBackTest.kt
M fragment/fragment/src/main/java/androidx/fragment/app/FragmentManager.java

Hash: 922bb8acc3661be78480dd40f3c582af8b87f935
Date: Mon Oct 21 20:45:54 2024

il...@google.com <il...@google.com> #6Oct 22, 2024 08:53PM

Marked as fixed.

We've fixed this internally and will be available in Fragment 1.8.5.