React 19 codemod: apply defaultProps when rendering a memo component

[jsnajdr]

Fixes a gap in the React 19 patch where a memo component with defaultProps doesn't get the default props applied. Example:

// definition
function MyCompInner( props ) { /* ... */ };
MyCompInner.defaultProps = { /* ... */ };
const MyComp = memo( MyCompInner );

// usage
<MyComp { ...props } />

The current JSX runtime doesn't see the defaultProps on MyCompInner because it's dealing with the wrapped MyComp. The React 18 solution was to apply the defaultProps in a special case inside the reconciler, looking both at the "outer" and the "inner" component:

https://github.com/react/react/blob/91d097b2c588a0977a7a10ed12512dc8a34e3a5b/packages/react-reconciler/src/ReactFiberBeginWork.js#L4258-L4263

This PR introduces a codemod that does the equivalent change in our patched React 19. It patches the body of the updateMemoComponent, covering all cases where the resolution is needed.

Testing instructions

• install the Stackable plugin (stackable-ultimate-gutenberg-blocks)
• edit a post and insert a stackable/button block

Before this PR, it would crash:

TypeError: Cannot read properties of undefined (reading 'includes') at Jr (stk.js?ver=3.20.2:2:530131)

After the PR, the error should be gone and the block is displayed.

[github-actions]

🤖 PR meta 🤖

🎉 Props

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: jsnajdr <jsnajdr@git.wordpress.org>
Co-authored-by: ciampo <mciampini@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

Updated as activity occurs, without notifying anyone named here. Add the props-bot label to refresh.

📦 Bundle size

Size Change: +242 B (0%)

Total Size: 8.52 MB

📦 View Changed

Filename	Size	Change
build/scripts/vendors/react-19.min.js	4.17 kB	+52 B (+1.26%)
build/scripts/vendors/react-dom-19.min.js	68 kB	+190 B (+0.28%)

_{1b33629 Run}

⚡ Performance

Show the results

Client side metrics exclude the server response time.

front-end-block-theme

Metric	609bf87	trunk	% Change
timeToFirstByte	32.7 ms +16.51% -3.36%	33.55 ms +16.1% -1.79%	-2.53%
largestContentfulPaint	64 ms +0% -12.5%	60 ms +10% -6.67%	6.67%
lcpMinusTtfb	25.35 ms +17.95% -2.37%	23.7 ms +20.25% -3.59%	6.96%
wpBeforeTemplate	17.27 ms +25.59% -3.01%	17.94 ms +11.15% -3.07%	-3.73%
wpTemplate	12.37 ms +4.85% -3.88%	12.85 ms +7% -4.82%	-3.74%
wpTotal	29.89 ms +15.42% -4.15%	30.72 ms +16.47% -2.18%	-2.7%
wpMemoryUsage	7.61 MB +0% -0%	7.58 MB +0% -0%	0.46%
wpDbQueries	17 +0% -0%	17 +0% -0%	0%

front-end-classic-theme

Metric	609bf87	trunk	% Change
timeToFirstByte	28.45 ms +11.6% -3.16%	28.95 ms +7.6% -4.84%	-1.73%
largestContentfulPaint	68 ms +5.88% -2.94%	64 ms +6.25% -0%	6.25%
lcpMinusTtfb	39.45 ms +2.41% -4.56%	36.7 ms +4.63% -1.36%	7.49%
wpBeforeTemplate	15.96 ms +9.15% -2.76%	15.85 ms +10.03% -1.7%	0.69%
wpTemplate	9.86 ms +9.13% -5.48%	9.78 ms +9.3% -3.89%	0.82%
wpTotal	25.99 ms +11.62% -4.23%	26.06 ms +9.98% -3.42%	-0.27%
wpMemoryUsage	6.25 MB +0% -0%	6.20 MB +0% -0%	0.71%
wpDbQueries	14 +0% -0%	14 +0% -0%	0%

media-processing

Metric	609bf87	trunk	% Change
mediaProcessingJpeg	220.79 ms +4.61% -1.63%	220.64 ms +3.36% -0.8%	0.07%
mediaProcessingAvif	3569.87 ms +0.41% -0.39%	3593.73 ms +0.44% -0.65%	-0.66%
mediaProcessingJpegToAvif	2471.54 ms +3.16% -0.39%	2503 ms +0.5% -0.19%	-1.26%

media-upload

Metric	609bf87	trunk	% Change
jpegUploadProcessing	1125.1 ms +25.25% -22.83%	881.64 ms +0.65% -0.64%	27.61%
pngUploadProcessing	147.04 ms +3.53% -1.41%	156.61 ms +5.09% -6.66%	-6.11%
largeJpegUploadProcessing	877.73 ms +0.77% -0.68%	902.16 ms +54.95% -1.36%	-2.71%
multipleImageUploadProcessing	1410.6 ms +2.59% -28.99%	999.8 ms +49.48% -0.83%	41.09%

post-editor

Metric	609bf87	trunk	% Change
serverResponse	253.21 ms +1.09% -8.95%	242.88 ms +9.64% -4.74%	4.25%
firstPaint	158.84 ms +32.03% -9.93%	207.56 ms +37.78% -20.71%	-23.47%
domContentLoaded	678.23 ms +2.4% -1.35%	699.66 ms +6.7% -5.66%	-3.06%
loaded	679.18 ms +2.38% -1.36%	700.75 ms +6.67% -5.67%	-3.08%
firstContentfulPaint	311.24 ms +4.01% -2.83%	321.37 ms +6.34% -7.88%	-3.15%
firstBlock	1960.62 ms +1.37% -1.33%	2018.02 ms +4.7% -2.78%	-2.84%
type	13.21 ms +1.89% -0.3%	13.18 ms +3.87% -3.03%	0.23%
typeWithoutInspector	13.24 ms +8.91% -1.59%	13.47 ms +10.69% -6.38%	-1.71%
typeWithTopToolbar	17.31 ms +13.63% -6.59%	17.48 ms +6.52% -7.38%	-0.97%
typeContainer	6.26 ms +8.15% -3.04%	6.08 ms +3.78% -2.3%	2.96%
focus	73.15 ms +10.94% -7.04%	69.26 ms +5.05% -4.95%	5.62%
firstFocus	140.31 ms +0% -0%	146.37 ms +0% -0%	-4.14%
selectAll	345.45 ms +1.38% -0.8%	332.02 ms +2.76% -4.28%	4.04%
listViewOpen	46.96 ms +1.9% -6.05%	44.84 ms +6.65% -2.32%	4.73%
inserterOpen	25.69 ms +4.94% -3.15%	24.76 ms +12.8% -6.83%	3.76%
inserterHover	8.75 ms +16.91% -3.66%	8.82 ms +12.13% -6.35%	-0.79%
inserterSearch	6.28 ms +8.76% -2.71%	6.41 ms +7.02% -1.4%	-2.03%
loadPatterns	426.34 ms +4.47% -1.15%	435.76 ms +4.91% -1.4%	-2.16%
wpTotal	245.43 ms +1.34% -9.05%	235.27 ms +10.12% -4.82%	4.32%
wpMemoryUsage	13.33 MB +0% -0%	13.30 MB +0% -0%	0.28%
wpDbQueries	54 +0% -0%	54 +0% -0%	0%

site-editor

Metric	609bf87	trunk	% Change
serverResponse	514.12 ms +2.15% -3.37%	534.08 ms +2.77% -6.18%	-3.74%
firstPaint	315.43 ms +9.59% -15.25%	291.62 ms +20.8% -8.05%	8.16%
domContentLoaded	1317.1 ms +1.37% -1.14%	1321.11 ms +1.69% -2.03%	-0.3%
loaded	1318.44 ms +1.37% -1.14%	1322.4 ms +1.68% -2.01%	-0.3%
firstContentfulPaint	533.69 ms +1.49% -2.2%	558.2 ms +2.92% -4.94%	-4.39%
firstBlock	5012.81 ms +0.34% -0.36%	4972.54 ms +1.26% -0.65%	0.81%
type	20.51 ms +7.26% -2.29%	21.6 ms +1.9% -7.22%	-5.05%
navigate	152.3 ms +6.41% -6.93%	144.3 ms +3.1% -3.19%	5.54%
loadPatterns	1547.07 ms +4.14% -3.87%	1537.61 ms +12.04% -5.07%	0.62%
loadPages	1093.67 ms +11.68% -1.03%	1072.56 ms +3.69% -2.38%	1.97%
wpTotal	502.71 ms +2.12% -3.47%	522.8 ms +2.55% -6.31%	-3.84%
wpMemoryUsage	12.38 MB +0% -0%	12.34 MB +0% -0%	0.3%
wpDbQueries	43 +2.33% -0%	43 +2.33% -0%	0%

_{1b33629 Run}

🏁 Flaky tests

Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

remembers sidebar dismissal between sessions in /test/e2e/specs/editor/various/preferences.spec.js, passed after 1 failed attempt.

Error: apiRequestContext.fetch: socket hang up
Call log:
  - → PUT http://localhost:8889/wp-json/wp/v2/users/me
    - user-agent: Playwright/1.63.0 (x64; ubuntu 24.04) node/24.20 CI/1
    - accept: */*
    - accept-encoding: gzip,deflate,br
    - X-WP-Nonce: 9367375a04
    - content-type: application/json
    - content-length: 37
    - cookie: wordpress_test_cookie=WP%20Cookie%20check; wordpress_logged_in_23778236db82f19306f247e20a353a99=admin%7C1791991681%7CjS8MS1g29ulYduozLSUm7ECDfymspJYsnp85VHbms1X%7C5ee39c78409c0dc1c6a2dc39b0a2e0c1ffb5ce4942cbc5a0fb8f608579f5a5fb; wp-settings-time-1=1791819398

    at RequestUtils.rest (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/rest.ts:112:39)
    at RequestUtils.resetPreferences (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/preferences.ts:9:13)
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/preferences.spec.js:11:22

_{1b33629 Run}

[ciampo]

LGTM 🚀

[Mamaduka]

Thanks, @jsnajdr!