Document each global ext/dom constant on its own row

[kocsismate]

Before these changes, the gen_stub.php --verify-manual command used to fail with an exception due to ext/DOM constants being wrongly formatted: the old and new constant counterparts were documented in the same row (e.g. DOM_VALIDATION_ERR / Dom\VALIDATION_ERR) which format cannot be recognized by gen_stub.php. Instead, let's document each constant on its own row.

Related to php/php-src#21484

[ndossche]

I think from a DX point of view, the new one is worse. I believe they should be documented together for ease.

[Girgias]

I agree with @ndossche here. If the tooling is struggling then it's a tooling issue. I am happy to modify the markup if it brings more consistency (e.g. replacing the table with a <variableentrylist>) or improves the DX while also facilitating tooling.

Converting the table to use the more typical format of a <variableentrylist> with multiple <term> tags that can hold the XML ID seems a better approach than duplicating rows.

[kocsismate]

I think the table format is correct here, as it includes the value, while the list format usually doesn't as far as I know.

There's a precedent for a similar situation at https://www.php.net/manual/en/reserved.constants.php: ZEND_THREAD_SAFE and PHP_ZTS. Here, the manual also duplicates them, but notes that PHP_ZTS is an alias of ZEND_THREAD_SAFE.

So in my opinion, a similar approach could work fine in case of ext/dom constants: we could mark them as aliases, and document them in the same row. What do you think?

Although, I should mention that personally, I don't find the separe row based approach worse, the page even looks cleaner for me because it's easier to overview the constant names. I attach two screenshots for comparison.

original:

new: