[wp-trac] [WordPress Trac] #53635: PHP 8.1: various compatibility fixes

[WordPress Trac]

#53635: PHP 8.1: various compatibility fixes
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 Reporter:  SergeyBiryukov                  |       Owner:  hellofromTonya
     Type:  task (blessed)                  |      Status:  accepted
 Priority:  normal                          |   Milestone:  5.9
Component:  General                         |     Version:
 Severity:  normal                          |  Resolution:
 Keywords:  php81 has-patch has-unit-tests  |     Focuses:  coding-
                                            |  standards
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Comment (by SergeyBiryukov):

 In [changeset:"51622" 51622]:
 {{{
 #!CommitTicketReference repository="" revision="51622"
 Code Modernization: Check the return type of `parse_url()` in
 `WP::parse_request()`.

 As per the PHP manual:
 > If the `component` parameter is omitted, an associative array is
 returned.
 > If the `component` parameter is specified, `parse_url()` returns a
 string (or an int, in the case of `PHP_URL_PORT`) instead of an array. If
 the requested component doesn't exist within the given URL, `null` will be
 returned.

 Reference: [https://www.php.net/manual/en/function.parse-
 url.php#refsect1-function.parse-url-returnvalues PHP Manual: parse_url():
 Return Values]

 In this case, `parse_url()` is called with the `PHP_URL_PATH` as
 `$component`. This will return `null` in the majority of cases, as –
 exсept for subdirectory-based sites – `home_url()` returns a URL without
 the trailing slash, like `http://example.org`.

 The return value of `parse_url()` was subsequently passed to `trim()`,
 leading to a `trim(): Passing null to parameter #1 ($string) of type
 string is deprecated` notice on PHP 8.1.

 Fixed by adjusting the logic flow to:
 * Only pass the return value of `parse_url()` to follow-on functions if it
 makes sense, i.e. if it isn't `null`, nor an empty string.
 * Preventing calls to `preg_replace()` and `trim()` further down in the
 function logic flow, when `preg_replace()`/`trim()` would have nothing to
 do anyhow.

 Follow-up to [25617].

 Props jrf, hellofromTonya, SergeyBiryukov.
 See #53635.
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/53635#comment:35>
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