[wp-trac] [WordPress Trac] #28517: Logic error in WP_Rewrite flush_rules

[WordPress Trac]

#28517: Logic error in WP_Rewrite flush_rules
---------------------------+-----------------------------
 Reporter:  numis          |      Owner:
     Type:  defect (bug)   |     Status:  new
 Priority:  normal         |  Milestone:  Awaiting Review
Component:  Rewrite Rules  |    Version:  trunk
 Severity:  normal         |   Keywords:
  Focuses:                 |
---------------------------+-----------------------------
 The current logic in flush_rules of WP_Rewrite is flawed:

 {{{
 if ( ! $hard || ! apply_filters( 'flush_rewrite_rules_hard', true ) ) {
     return;
 }
 }}}

 Given the four possible scenarios:

 $hard has two unique values:
 * true (by default)
 * false

 Casting apply_filters( 'flush_rewrite_rules_hard', true ) to a boolean
 also has two unique values:
 * true (by default)
 * true (a filter returns a value that evaluates to true)
 * false (a filter returns a value that evaluates to false)

 =============================================

 If $hard is true and either no filters are added, or a filter is added
 that returns true:
 {{{
 ! true  || ! true = false || false = false
 }}}
 {{{
 #!html
 <span style="color: red; font-weight: strong;" >UNINTENTIONAL
 FAILURE</span>
 }}}

 =============================================

 If $hard is true and a filter is added that returns false:
 {{{
 ! true || ! false = false || true = true
 }}}
 {{{
 #!html
 <span style="color: orange; font-weight: strong;" >UNINTENTIONAL
 SUCCESS</span>
 }}}

 =============================================

 If $hard is false and either no filters are added, or a filter is added
 that returns true:
 {{{
 ! false || ! true = true || false = true
 }}}
 {{{
 #!html
 <span style="color: orange; font-weight: strong;" >UNINTENTIONAL
 SUCCESS</span>
 }}}

 =============================================

 If $hard is false and a filter is added that returns false:
 {{{
 ! false || ! false = true || true = true
 }}}
 {{{
 #!html
 <span style="color: red; font-weight: strong;" >UNINTENTIONAL
 FAILURE</span>
 }}}

 =============================================

 As seen above, 50% of the unique scenarios give an unexpected response.
 While the other 50% of the scenarios give the expected response, but for
 the wrong reason.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/28517>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform