[wp-trac] [WordPress Trac] #32573: Change in wp_print_styles() causes fatal error if $wp_styles is not set

[WordPress Trac]

#32573: Change in wp_print_styles() causes fatal error if $wp_styles is not set
---------------------------+-----------------------------
 Reporter:  DrProtocols    |      Owner:
     Type:  defect (bug)   |     Status:  new
 Priority:  normal         |  Milestone:  Awaiting Review
Component:  Script Loader  |    Version:  trunk
 Severity:  normal         |   Keywords:
  Focuses:                 |
---------------------------+-----------------------------
 In 4.3-alpha there is a change in wp_print_styles() such that the final
 return statement has become:
 {{{
         return $wp_styles->do_items( $handles );
 }}}
 whereas in 4.2.2 the statement is:
 {{{
         return wp_styles()->do_items( $handles );
 }}}
 The change appears to be due to this ticket:

 https://core.trac.wordpress.org/ticket/32444#comment:43

 which does not seem to take into account the actual context of this
 statement. The upshot is that there is now an implicit assumption that the
 global $wp_styles is already set to an instantiation of the WP_Styles
 object and when this is not the case the function fails with a fatal
 error:
 {{{
 [Sat Jun 06 14:19:24.795479 2015] [:error] [pid 7955] [client
 127.0.0.1:59179] PHP Fatal error:  Call to a member function do_items() on
 a non-object in /Users/ambiguous/Sites/wptest.dev/wp-includes/functions
 .wp-styles.php on line 64
 }}}

 It cannot be assumed that the global $wp_styles is already set to an
 instantiated WP_Styles object and the explicit use of the wp_styles()
 function was to instantiate a WP_Styles object and assign to the global
 $wp_styles if that was not already the case.

 The wp_print_styles() function has an explicit requirement that the global
 $wp_styles is a valid instantiation of a WP_Styles object if it is
 necessary to use the global:
 {{{
 * @global WP_Styles $wp_styles The WP_Styles object for printing styles.
 }}}
 Either the change needs to be reverted to call wp_styles() in the return
 statement or an update must be made earlier in the function to add an else
 clause in prior conditional so that $wp_styles global will be valid when
 required.

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Ticket URL: <https://core.trac.wordpress.org/ticket/32573>
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