Bug: PreGetPosts warns when the early is_main_query() return is not the first statement in its if #902

Bug Description

The PreGetPosts sniff warns when a pre_get_posts callback changes the query without checking is_main_query() first. A callback that returns early for every other query has made that check, so it should not get the warning.

It does get the warning when the early return is not the first statement inside the if. Logging a message before returning is enough to cause it.

Expected: no warning for the snippet below.

Actual: a warning on the $query->set() line. Remove the do_log() line and the warning goes away.

The cause is in PreGetPostsSniff::isEarlyMainQueryCheck(). It looks for the return with findNext() in local mode, which stops at the first statement terminator, so only the first statement in the if body is searched.

@GaryJones found this while reviewing #901.

Minimal Code Snippet

add_action( 'pre_get_posts', function( $query ) {
	if ( ! $query->is_main_query() ) {
		do_log( 'x' );
		return;
	}
	$query->set( 'cat', '-5' );
} );

Error Code

WordPressVIPMinimum.Hooks.PreGetPosts.PreGetPosts

Main WP_Query is being modified without $query->is_main_query() check. Needs manual inspection.

Environment

Tested Against main branch?

• I have verified the issue still exists in the main branch of VIPCS.
• I have verified the issue still exists in the develop branch of VIPCS.