Components: Fix polymorphism typings leaking as prop

[aduth]

What?

Related (extracted from): #70064 (comment)

Updates component polymorphism typings in @wordpress/component's WordPressComponentProps to fix an issue where typings would wrongly surface as as an available prop.

Why?

Typings accuracy.

How?

The previous issue is a result of how boolean interpreted as a union of true | false in the check IsPolymorphic extends true produces a union type { as?: … } | {}, therefore presenting as as an available prop when it is in-fact not intended as one.

Testing Instructions

Type-check should pass: npm run typecheck

Documentation update should produce no local changes: npm run docs:build

Bonus points: Verify that you cannot add an as prop to an instance of Menu component.

Use of AI Tools

Used Cursor IDE + Auto model to research and implement, plus Claude Code + Opus 4.5 for an adversarial review. Changes reviewed manually by myself.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

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: aduth <aduth@git.wordpress.org>
Co-authored-by: ciampo <mciampini@git.wordpress.org>

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

[github-actions]

🤖 PR meta 🤖

📦 Bundle size

Size Change: 0 B

Total Size: 8.06 MB

_{35cd79f Run}

⚡ Performance

Show the results

Client side metrics exclude the server response time.

front-end-block-theme

Metric	0e76ca7c8cca4ca9873ec2d1ad93459ccf1430ee	trunk	% Change
timeToFirstByte	49.8 ms +2.11% -3.01%	49.6 ms +3.43% -2.52%	0.4%
largestContentfulPaint	86 ms +6.98% -2.33%	86 ms +6.98% -6.98%	0%
lcpMinusTtfb	35.9 ms +14.35% -7.66%	33.15 ms +25.19% -3.62%	8.3%
wpBeforeTemplate	23.27 ms +4.68% -0.95%	23.49 ms +3.92% -2.21%	-0.94%
wpTemplate	22.64 ms +2.47% -5.61%	22.24 ms +4.54% -3.87%	1.8%
wpTotal	46.2 ms +2.21% -3.07%	46.02 ms +3.06% -3.13%	0.39%
wpMemoryUsage	7.53 MB +0% -0%	7.49 MB +0% -0%	0.45%
wpDbQueries	17 +0% -0%	17 +0% -0%	0%

front-end-classic-theme

Metric	0e76ca7c8cca4ca9873ec2d1ad93459ccf1430ee	trunk	% Change
timeToFirstByte	37.75 ms +3.18% -4.24%	32.35 ms +4.64% -1.39%	16.69%
largestContentfulPaint	88 ms +4.55% -0%	76 ms +2.63% -0%	15.79%
lcpMinusTtfb	51.65 ms +1.26% -3.58%	43.8 ms +1.03% -0.68%	17.92%
wpBeforeTemplate	20.56 ms +1.65% -1.75%	20.41 ms +2.01% -2.25%	0.73%
wpTemplate	13.09 ms +7.87% -2.29%	9.23 ms +4.88% -0.98%	41.82%
wpTotal	34.67 ms +3.26% -4.53%	29.55 ms +4.87% -1.56%	17.33%
wpMemoryUsage	5.52 MB +0% -0%	5.37 MB +0% -0%	2.65%
wpDbQueries	14 +0% -0%	10 +0% -0%	40%

media-processing

Metric	0e76ca7c8cca4ca9873ec2d1ad93459ccf1430ee	trunk	% Change
mediaProcessingJpeg	377.38 ms +2.67% -0.51%	380.03 ms +1.29% -0.54%	-0.7%
mediaProcessingAvif	5604.87 ms +0.1% -0.16%	5603 ms +0.17% -0.13%	0.03%
mediaProcessingJpegToAvif	3840.63 ms +0.36% -0.15%	3828.78 ms +0.11% -0.18%	0.31%

media-upload

Metric	0e76ca7c8cca4ca9873ec2d1ad93459ccf1430ee	trunk	% Change
jpegUploadProcessing	1421.8 ms +37.08% -0.68%	1422.76 ms +0.43% -1.2%	-0.07%
pngUploadProcessing	206.57 ms +5.5% -2.4%	211.41 ms +7.27% -6.27%	-2.29%
largeJpegUploadProcessing	1415.6 ms +1.01% -0.43%	1412.31 ms +0.4% -0.47%	0.23%
multipleImageUploadProcessing	1520.26 ms +1.73% -0.68%	1533.27 ms +0.43% -3.18%	-0.85%

post-editor

Metric	0e76ca7c8cca4ca9873ec2d1ad93459ccf1430ee	trunk	% Change
serverResponse	440.61 ms +1.38% -10.62%	385.1 ms +10.86% -1.47%	14.41%
firstPaint	229.16 ms +20.48% -4.19%	248.86 ms +10.66% -17.61%	-7.92%
domContentLoaded	1261.79 ms +2.94% -1.83%	1258.96 ms +1.82% -1.06%	0.22%
loaded	1262.89 ms +2.96% -1.83%	1260.22 ms +1.82% -1.05%	0.21%
firstContentfulPaint	427.8 ms +2.87% -5.76%	422.56 ms +3.65% -2.56%	1.24%
firstBlock	3422.9 ms +0.99% -0.58%	3413.08 ms +1.15% -0.61%	0.29%
type	14.48 ms +14.64% -0.9%	14.87 ms +7.4% -1.41%	-2.62%
typeWithoutInspector	14.61 ms +4.04% -4.79%	14.87 ms +1.88% -9.08%	-1.75%
typeWithTopToolbar	18.28 ms +10.39% -4.05%	17.25 ms +6.09% -4.7%	5.97%
typeContainer	9.41 ms +11.58% -8.82%	9.13 ms +4.05% -6.68%	3.07%
focus	78.34 ms +4.66% -11.41%	72.69 ms +33.77% -6.07%	7.77%
firstFocus	175.99 ms +0% -0%	168.77 ms +0% -0%	4.28%
selectAll	536.76 ms +4.72% -0.25%	548.41 ms +0.28% -0.81%	-2.12%
listViewOpen	68.77 ms +22.13% -9.02%	64.49 ms +13.26% -6.78%	6.64%
inserterOpen	23.41 ms +10.85% -7.43%	23.51 ms +8.76% -10.25%	-0.43%
inserterHover	3.76 ms +12.23% -10.64%	4.05 ms +12.84% -10.86%	-7.16%
inserterSearch	7.97 ms +4.14% -7.65%	8.59 ms +9.2% -4.77%	-7.22%
loadPatterns	651.47 ms +3.22% -3.03%	639.73 ms +4.13% -2.38%	1.84%
wpTotal	429.41 ms +1.42% -10.74%	374.21 ms +11.1% -1.48%	14.75%
wpMemoryUsage	13.06 MB +0% -0%	13.03 MB +0% -0%	0.28%
wpDbQueries	54 +0% -0%	54 +0% -1.85%	0%

site-editor

Metric	0e76ca7c8cca4ca9873ec2d1ad93459ccf1430ee	trunk	% Change
serverResponse	520.3 ms +3.75% -5.7%	481.65 ms +13.35% -1.52%	8.02%
firstPaint	268.01 ms +9.82% -12.2%	246.18 ms +12.47% -9.93%	8.87%
domContentLoaded	1384.23 ms +1.26% -1.24%	1369.02 ms +1.92% -1.89%	1.11%
loaded	1385.47 ms +1.25% -1.26%	1370.25 ms +1.91% -1.9%	1.11%
firstContentfulPaint	440.42 ms +1.34% -0.68%	429.89 ms +1.71% -0.8%	2.45%
firstBlock	4475.38 ms +1.4% -0.4%	4435.55 ms +0.75% -0.49%	0.9%
type	14.15 ms +7.07% -6.36%	14.61 ms +6.37% -1.3%	-3.15%
navigate	103.1 ms +4.66% -1.38%	104.75 ms +2% -11.06%	-1.58%
loadPatterns	1626.05 ms +5.69% -12.13%	1450.53 ms +6.79% -12.09%	12.1%
loadPages	1100.81 ms +1.36% -1.58%	1071.64 ms +2.59% -0.35%	2.72%
wpTotal	510.7 ms +3.72% -5.91%	472.22 ms +13.53% -1.64%	8.15%
wpMemoryUsage	12.07 MB +0% -0%	12.04 MB +0% -0%	0.3%
wpDbQueries	43 +2.33% -0%	43 +2.33% -0%	0%

_{35cd79f Run}

🏁 Flaky tests

Show the failures

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.

refuses the drop and uploads nothing in /test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js, passed after 1 failed attempt.

Error: expect(received).toHaveLength(expected)

Expected length: 0
Received length: 2
Received array:  [{"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=97"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/97", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-97", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-09-09T20:58:04", "date_gmt": "2026-09-09T20:58:04", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "10x10_e2e_test_image_z9T8jK-1.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png"}, "id": 97, "link": "http://localhost:8889/10x10_e2e_test_image_z9t8jk-2/", "media_details": {"file": "2026/09/10x10_e2e_test_image_z9T8jK-1.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-09-09T20:58:04", "modified_gmt": "2026-09-09T20:58:04", "ping_status": "closed", "post": null, "slug": "10x10_e2e_test_image_z9t8jk-2", "source_url": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK-1.png", "status": "inherit", "template": "", "title": {"rendered": "10x10_e2e_test_image_z9T8jK"}, "type": "attachment"}, {"_links": {"about": [{"href": "http://localhost:8889/wp-json/wp/v2/types/attachment"}], "author": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/users/1"}], "collection": [{"href": "http://localhost:8889/wp-json/wp/v2/media"}], "replies": [{"embeddable": true, "href": "http://localhost:8889/wp-json/wp/v2/comments?post=93"}], "self": [{"href": "http://localhost:8889/wp-json/wp/v2/media/93", "targetHints": {"allow": ["GET", "POST", "PUT", "PATCH", "DELETE"]}}]}, "alt_text": "", "author": 1, "caption": {"rendered": ""}, "class_list": ["post-93", "attachment", "type-attachment", "status-inherit", "hentry", "entry"], "comment_status": "open", "date": "2026-09-09T20:57:45", "date_gmt": "2026-09-09T20:57:45", "description": {"rendered": "<p class=\"attachment\"><a href='http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png'><img loading=\"lazy\" decoding=\"async\" width=\"10\" height=\"10\" src=\"http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png\" class=\"attachment-medium size-medium\" alt=\"\" style=\"width:100%;height:100%;max-width:10px;\" /></a></p>
"}, "featured_media": 0, "filename": "10x10_e2e_test_image_z9T8jK.png", "filesize": 80, "guid": {"rendered": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png"}, "id": 93, "link": "http://localhost:8889/10x10_e2e_test_image_z9t8jk/", "media_details": {"file": "2026/09/10x10_e2e_test_image_z9T8jK.png", "filesize": 80, "height": 10, "image_meta": {"alt": "", "aperture": "0", "camera": "", "caption": "", "copyright": "", "created_timestamp": "0", "credit": "", "focal_length": "0", "iso": "0", "keywords": [], "orientation": "0", "shutter_speed": "0", "title": ""}, "sizes": {}, "width": 10}, "media_type": "image", "meta": [], "mime_type": "image/png", "modified": "2026-09-09T20:57:45", "modified_gmt": "2026-09-09T20:57:45", "ping_status": "closed", "post": null, "slug": "10x10_e2e_test_image_z9t8jk", "source_url": "http://localhost:8889/wp-content/uploads/2026/09/10x10_e2e_test_image_z9T8jK.png", "status": "inherit", "template": "", "title": {"rendered": "10x10_e2e_test_image_z9T8jK"}, "type": "attachment"}]
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/various/single-file-placeholder-drop.spec.js:71:45

_{From d406ce7, not the current head. Run}

[ciampo]

Looking at the manifest checks, it looks like key has now become an actual Dropdown prop, meaning that React.RefAttributes also adds the reserved key attribute.

Should we make RefProps add only ref, then regenerate the manifest to confirm the error is gone?

[ciampo]

This PR needs a rebase + moving this entry under the new unreleased section