COMMENTS_TEMPLATE: cannot define a constant twice in PHP

[kitchin]

A minor PHP issue in wp-includes/comment-template.php in comments_template() :

if ( !defined('COMMENTS_TEMPLATE') || !COMMENTS_TEMPLATE)
	define('COMMENTS_TEMPLATE', true);

PHP does not allow constants to be re-defined, so the clause "!COMMENTS_TEMPLATE" can have no effect other than raise a warning.

The patch removes the clause.

Normally this warning would happen if comments_template() is called twice by the theme, but the subsequent require() statement would raise an error anyway.

In one edge case it might not raise an error:

1. Theme calls comments_template()
2. Theme calls comments_template() again with a different parameter or after a different filter is in effect.

So the patch loses a warning in that case.

I grepped the codebase and did not find any similar clause before a define().

The conditional code around the define() was added in this changeset: ​http://core.trac.wordpress.org/changeset/10953

[scribu]

Agreed, the code decides to define a constant based on it's value, which makes 0 sense.

[nacin]

What's the point of COMMENTS_TEMPLATE, anyway? Seems like it could disappear. Are people relying on it to detect something within a template?

[ryan]

In [21330]:

Don't attempt to define the COMMENTS_TEMPLATE constant twice. Props kitchin. fixes #21337