`taxonomy_exists()` does not guard against non-string arguments.

[costdev]

Follow-up to #56336.

While testing the issue reported by @dd32, I came across a similar warning/error. This can be produced, for example, when using Yoast SEO for sitemaps.

Warning: Illegal offset type in isset or empty in src/wp-includes/taxonomy.php on line 340

Tested and verified by @peterwilsoncc

Adding an is_string( $taxonomy ) check to the condition in ​taxonomy_exists resolves the issue. The $taxonomy argument is documented as a string.

Trac ticket: https://core.trac.wordpress.org/ticket/56338

[costdev]

Introduced in [35718] in WordPress 3.0, formerly is_taxonomy() in WordPress 2.3.

​PR 3066 is ready for review by a committer.

@costdev Can you please add test coverage for the special characters?

@costdev Can you please add test coverage for the special characters?

Hi @mukeshpanchal27, I'm not sure what you mean. Which special characters will trigger an illegal offset warning/error?

[mukesh27]

Hi there,

PR looks good to me.

[audrasjb]

Looks good to go. Self-assigning for commit.

[audrasjb]

In 53869:

Taxonomy: Prevent non string taxonomy names generating warnings or errors.

This changeset adds an is_string( $taxonomy ) check to the condition in taxonomy_exists(), to ensure false is returned when the $taxonomy is not a string.

Follow-up to [35718].

Props costdev, peterwilsoncc, mukesh27.
Fixes #56338.
See #56336.

committed in https://core.trac.wordpress.org/changeset/53869

[SergeyBiryukov]

In 54052:

Tests: Correct the @covers tag syntax in a taxonomy_exists() test with non-string taxonomy.

This addresses a notice when generating the code coverage report:

"@covers :taxonomy_exists" is invalid

Follow-up to [53869].

See #56338, #55652.