Block supports: Avoid warning for non string class attributes #5486

dmsnell · 2023-10-13T20:12:05Z

Trac ticket: Core-59622
Gutenberg backport: WordPress/gutenberg#71594

Block Supports: Avoid throwing warning when checking for class attribute as string.

When encountering HTML tags with boolean or missing tags, the get_attribute()
method in the HTML API returns true and null, respectively. If these returned
values are sent directly into string comparison functions then as of PHP 8.0 they
will throw E_DEPRECATED errors.

In this patch, block supports is enhanced to check that the class value is a
string before it performs string operations on it.

There is a small likelihood of any real damage in production here, as these are only deprecation notices and the logic in these cases isn't affected by the change. That is,
the intention of the code is maintained even when the attribute values aren't strings.

For background support there's a tiny but benign defect when the style attribute is
boolean. It will erroneously inject a ; at the beginning of the wrapper's new style
value. As this doesn't impact the rendering of the wrapper, it's not a true defect.

Further review belongs to block rendering code, but this will occur in the Gutenberg
repo since that PHP comes back into Core through the generated packages.

Testing

There should be no functional or visual changes in this patch. Please consult blocks with layout and background support to verify that this hasn't adversely affected existing rendering. Verify that the test suite continues to pass.

hellofromtonya · 2023-10-16T13:48:39Z

@dmsnell 10 Test_Block_Supports_Layout tests are failing from this change. Can you take a look please?

peterwilsoncc · 2023-10-17T03:37:31Z

Could the tests be failing because the markup is missing a closing div? <div><div class="wp-block-group"></div>

To an extent I'm asking the silly question because I'd sure feel silly if I didn't and it turned out to be the case ;)

dmsnell · 2023-10-17T07:30:49Z

@peterwilsoncc no, and I wasn't sure what happened. I tried a few things that I thought should fix it, so I'm curious when my change is at fault or if the implicit behavior this removed is at fault, even though from the unit tests it looks like it should be fine.

sirreal

This needs to be updated, but generally looks like a good fix for some subtle issues.

sirreal · 2025-07-22T11:49:13Z

src/wp-includes/block-supports/background.php

 			$updated_style  = '';

-			if ( ! empty( $existing_style ) ) {
+			if ( is_string( $existing_style ) && ! empty( $existing_style ) ) {


Note for reviewers: the empty on this line would not have any issues, but would do the wrong thing if passed true, ! empty( true ) evaluates to true, so this block would be entered if if $existing_style is true, for example with HTML like <div style>. Inside the block, $existing_style is expected to be a string and is passed to string methods.

github-actions · 2025-09-03T18:28:57Z

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.

Core Committers: Use this line as a base for the props when committing in SVN:

Props dmsnell, jonsurrell, hellofromtonya, peterwilsoncc.

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github-actions · 2025-09-03T18:43:12Z

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dmsnell · 2025-09-03T18:48:19Z

I have removed the added tests since I had trouble figuring out what the function should be doing, and since it seemed like they didn’t add much value anyway. The existing tests verify the passing behaviors and will catch regressions. This patch only adds a bit of safety to handle some edge cases and therefore need not be distracted by asserting that those edge cases fail.

Trac ticket: Core-59622 This is a backport of WordPress/wordpress-develop#5486, which introduces an additional check for non-string values of the `class` attribute when rendering background support for blocks. This check avoids issuing a warning when a boolean `true` value of the attribute is passed on to `str_ends_with()`.

…ute as string. When encountering HTML tags with boolean or missing tags, the `get_attribute()` method in the HTML API returns `true` and `null`, resepectively. If these returned values are sent directly into string comparison functions then as of PHP 8.0 they will throw `E_DEPRECATED` errors. In this patch, block supports is enhanced to check that the `class` value is a string before it performs string operations on it.

Trac ticket: Core-59622 This is a backport of WordPress/wordpress-develop#5486, which introduces an additional check for non-string values of the `class` attribute when rendering background support for blocks. This check avoids issuing a warning when a boolean `true` value of the attribute is passed on to `str_ends_with()`. Co-authored-by: Tonya Mork <[email protected]> Co-authored-by: Peter Wilson <[email protected]> Co-authored-by: Jon Surrell <[email protected]> Github-PR: 71594 Github-PR-URL: #71594 Branch-name: backport/block-supports-background-non-string-attribute-check

…ute as string. When encountering HTML tags with boolean or missing tags, the get_attribute() method in the HTML API returns true and null, respectively. If these returned values are sent directly into string comparison functions then as of PHP 8.0 they will throw E_DEPRECATED errors. In this patch, block supports is enhanced to check that the class value is a string before it performs string operations on it. Also in this patch: using `assertEqualHTML()` in background support test instead of `assertSame()` Developed in #5486 Discussed in https://core.trac.wordpress.org/ticket/59622 Props dmsnell, jonsurrell, hellofromtonya, peterwilsoncc. Fixes #59622. git-svn-id: https://develop.svn.wordpress.org/trunk@60727 602fd350-edb4-49c9-b593-d223f7449a82

github-actions · 2025-09-10T20:26:14Z

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 60727
GitHub commit: 1ebc4c5

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.

…ute as string. When encountering HTML tags with boolean or missing tags, the get_attribute() method in the HTML API returns true and null, respectively. If these returned values are sent directly into string comparison functions then as of PHP 8.0 they will throw E_DEPRECATED errors. In this patch, block supports is enhanced to check that the class value is a string before it performs string operations on it. Also in this patch: using `assertEqualHTML()` in background support test instead of `assertSame()` Developed in WordPress/wordpress-develop#5486 Discussed in https://core.trac.wordpress.org/ticket/59622 Props dmsnell, jonsurrell, hellofromtonya, peterwilsoncc. Fixes #59622. Built from https://develop.svn.wordpress.org/trunk@60727 git-svn-id: http://core.svn.wordpress.org/trunk@60063 1a063a9b-81f0-0310-95a4-ce76da25c4cd

…ute as string. When encountering HTML tags with boolean or missing tags, the get_attribute() method in the HTML API returns true and null, respectively. If these returned values are sent directly into string comparison functions then as of PHP 8.0 they will throw E_DEPRECATED errors. In this patch, block supports is enhanced to check that the class value is a string before it performs string operations on it. Also in this patch: using `assertEqualHTML()` in background support test instead of `assertSame()` Developed in WordPress/wordpress-develop#5486 Discussed in https://core.trac.wordpress.org/ticket/59622 Props dmsnell, jonsurrell, hellofromtonya, peterwilsoncc. Fixes #59622. Built from https://develop.svn.wordpress.org/trunk@60727 git-svn-id: https://core.svn.wordpress.org/trunk@60063 1a063a9b-81f0-0310-95a4-ce76da25c4cd

Trac ticket: Core-59622 This is a backport of WordPress/wordpress-develop#5486, which introduces an additional check for non-string values of the `class` attribute when rendering background support for blocks. This check avoids issuing a warning when a boolean `true` value of the attribute is passed on to `str_ends_with()`. Co-authored-by: Tonya Mork <[email protected]> Co-authored-by: Peter Wilson <[email protected]> Co-authored-by: Jon Surrell <[email protected]> Github-PR: 71594 Github-PR-URL: #71594 Branch-name: backport/block-supports-background-non-string-attribute-check

Trac ticket: Core-59622 This is a backport of WordPress/wordpress-develop#5486, which introduces an additional check for non-string values of the `class` attribute when rendering background support for blocks. This check avoids issuing a warning when a boolean `true` value of the attribute is passed on to `str_ends_with()`. Co-authored-by: Tonya Mork <[email protected]> Co-authored-by: Peter Wilson <[email protected]> Co-authored-by: Jon Surrell <[email protected]> Co-authored-by: George Mamadashvili <[email protected]> Github-PR: 71594 Github-PR-URL: #71594 Branch-name: backport/block-supports-background-non-string-attribute-check Trac-ticket: 59622

Trac ticket: Core-59622 This is a backport of WordPress/wordpress-develop#5486, which introduces an additional check for non-string values of the `class` attribute when rendering background support for blocks. This check avoids issuing a warning when a boolean `true` value of the attribute is passed on to `str_ends_with()`. Co-authored-by: Tonya Mork <[email protected]> Co-authored-by: Peter Wilson <[email protected]> Co-authored-by: Jon Surrell <[email protected]> Co-authored-by: George Mamadashvili <[email protected]> Github-PR: 71594 Github-PR-URL: WordPress#71594 Branch-name: backport/block-supports-background-non-string-attribute-check Trac-ticket: 59622

Trac ticket: Core-59622 This is a backport of WordPress/wordpress-develop#5486, which introduces an additional check for non-string values of the `class` attribute when rendering background support for blocks. This check avoids issuing a warning when a boolean `true` value of the attribute is passed on to `str_ends_with()`. Co-authored-by: Tonya Mork <[email protected]> Co-authored-by: Peter Wilson <[email protected]> Co-authored-by: Jon Surrell <[email protected]> Co-authored-by: George Mamadashvili <[email protected]> Github-PR: 71594 Github-PR-URL: WordPress/gutenberg#71594 Branch-name: backport/block-supports-background-non-string-attribute-check Trac-ticket: 59622 Source: WordPress/gutenberg@54564ab

…ute as string. When encountering HTML tags with boolean or missing tags, the get_attribute() method in the HTML API returns true and null, respectively. If these returned values are sent directly into string comparison functions then as of PHP 8.0 they will throw E_DEPRECATED errors. In this patch, block supports is enhanced to check that the class value is a string before it performs string operations on it. Also in this patch: using `assertEqualHTML()` in background support test instead of `assertSame()` Developed in WordPress#5486 Discussed in https://core.trac.wordpress.org/ticket/59622 Props dmsnell, jonsurrell, hellofromtonya, peterwilsoncc. Fixes #59622. git-svn-id: https://develop.svn.wordpress.org/trunk@60727 602fd350-edb4-49c9-b593-d223f7449a82

dmsnell force-pushed the block-supports/avoid-warning-for-non-string-class-attributes branch 2 times, most recently from 482f394 to bce9b11 Compare October 16, 2023 18:49

dmsnell force-pushed the block-supports/avoid-warning-for-non-string-class-attributes branch from 75092c5 to 0c6e8e7 Compare October 31, 2023 08:00

dmsnell force-pushed the block-supports/avoid-warning-for-non-string-class-attributes branch from 0c6e8e7 to 797c0fa Compare December 19, 2023 20:40

sirreal reviewed Jul 22, 2025

View reviewed changes

dmsnell force-pushed the block-supports/avoid-warning-for-non-string-class-attributes branch from 797c0fa to 7ae9381 Compare September 3, 2025 18:28

dmsnell force-pushed the block-supports/avoid-warning-for-non-string-class-attributes branch from 6edbeb1 to 4c1a0f5 Compare September 10, 2025 19:55

dmsnell mentioned this pull request Sep 10, 2025

Backport: Avoid warning for non-string class attributes. WordPress/gutenberg#71594

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dmsnell force-pushed the block-supports/avoid-warning-for-non-string-class-attributes branch from 4c1a0f5 to 3ba1e75 Compare September 10, 2025 20:06

github-actions bot closed this Sep 10, 2025

dmsnell deleted the block-supports/avoid-warning-for-non-string-class-attributes branch September 10, 2025 20:26

github-actions bot mentioned this pull request Oct 16, 2025

PHP backports for WP 6.9 WordPress/gutenberg#72379

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dmsnell commented Oct 13, 2023 •

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