[wp-trac] [WordPress Trac] #48272: "Undefined offset" warning in add_query_arg()

[WordPress Trac]

#48272: "Undefined offset" warning in add_query_arg()
-------------------------------+------------------------------
 Reporter:  sumitsingh         |       Owner:  (none)
     Type:  defect (bug)       |      Status:  new
 Priority:  normal             |   Milestone:  Awaiting Review
Component:  General            |     Version:  5.2.3
 Severity:  normal             |  Resolution:
 Keywords:  reporter-feedback  |     Focuses:  administration
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Comment (by jrf):

 I've just looked into this and the suggested solution is incorrect.

 As per the documentation,
 [https://developer.wordpress.org/reference/functions/add_query_arg/
 `add_query_arg()`] can be called in two ways:
 {{{#!php
 <?php
 // Using a single key and value:
 add_query_arg( 'key', 'value', 'http://example.com' );

 // Using an associative array:
 add_query_arg( array(
     'key1' => 'value1',
     'key2' => 'value2',
 ), 'http://example.com' );
 }}}

 The code which is causing the notice is the `else` case here:
 {{{#!php
 <?php
         if ( is_array( $args[0] ) ) {
                 foreach ( $args[0] as $k => $v ) {
                         $qs[ $k ] = $v;
                 }
         } else {
                 $qs[ $args[0] ] = $args[1];
         }
 }}}

 The only way the error could be created is if `add_query_arg()` gets
 called with only **one** argument, not two or three and that one argument
 is a string, in other words, the ''single key and value'' pattern from
 above, but without a value.

 First off: I expect this to be a code error in the code calling the
 function, so I would like to see a backtrace so we can determine what
 plugin or theme is causing it and then it should be reported to the
 plugin/theme author.

 Secondly, I'm not completely read up on the RFCs which apply to URL build-
 ups, so someone who is will need to chime in here, but basically it needs
 to be determined whether setting a key without a value as part of the
 query string should be allowed at all.

 Think: `https://example.com/?key1=value1&key2&key3=value3` <= `key2` in
 this URL.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/48272#comment:5>
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