Undo breakage with Spacer block and Row/Stack

[stokesman]

Description

Inserting or moving a Spacer block into a Row/Stack block stops undo from working. Moving a Spacer block out of a Row/Stack has the same effect. I expect undo to keep working.

Step-by-step reproduction instructions

1. Insert a Row or Stack block.
2. Insert a Spacer into the previously inserted Row or Stack.
3. Try to undo.

Screenshots, screen recording, code snippet

spacer-v-row-stack-history-breakage.mp4

Environment info

WP 6.7.1 / Gutenberg plugin trunk
Chrome 130
macOS 13.7.1

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure

[stokesman]

It looks like this is caused by an effect in the Spacer block that sets some attributes.

Short-circuit the effect in question.

diff --git a/packages/block-library/src/spacer/edit.js b/packages/block-library/src/spacer/edit.js
index 1e0ffb9700..cf8fd7d144 100644
--- a/packages/block-library/src/spacer/edit.js
+++ b/packages/block-library/src/spacer/edit.js
@@ -256,6 +256,7 @@ const SpacerEdit = ( {
 	};
 
 	useEffect( () => {
+		return;
 		if (
 			isFlexLayout &&
 			selfStretch !== 'fill' &&

I suppose it may be fixed by some application of __unstableMarkNextChangeAsNotPersistent.

[yogeshbhutkar]

gutenberg/packages/block-library/src/spacer/edit.js

Line 272 in a411f33

setAttributes( {

I believe these direct setAttribute calls are causing this issue, and using __unstableMarkNextChangeAsNotPersistent() before calling setAttribute should fix the issue.

I'll try creating a PR to incorporate this fix.