Remove discouraged `@return void` annotations

[flixos90]

See ​https://developer.wordpress.org/coding-standards/inline-documentation-standards/php/#:~:text=Note%3A%20%40return%20void%20should%20not%20be%20used%20outside%20of%20the%20default%20bundled%20themes.

Note: @return void should not be used outside of the default bundled themes.

There were a few PHP instances of @return void added in 6.4, and other recent releases and thus violate that guideline.

Let's fix this throughout, except for themes (per the above), third-party libraries, and PHP compatibility code.

Also see relevant Gutenberg change for reference: ​https://github.com/WordPress/gutenberg/pull/55237

Trac ticket: https://core.trac.wordpress.org/ticket/59619

Should the docs be updated to say that @return void is also allowed in third-party libraries and PHP compatibility code?

Great idea @tellthemachines! I've opened a PR in ​https://github.com/WordPress/wpcs-docs/pull/133.

[flixos90]

In 56943:

General: Remove discouraged @return void annotations.

Such @return void annotations must not be used in WordPress core's PHP code, except bundled themes, third-party libraries, and PHP compatibility shims.

Props isabel_brison, swissspidy.
Fixes #59619.

Committed in https://core.trac.wordpress.org/changeset/56943

[afercia]

Just noticed that [56943] mentions three exceptions:

• bundled themes
• third-party libraries
• PHP compatibility shims.

That makes sense, but the documentation linked in this issue ​only mentions bundled themes.

I guess it's worth considering updating the documentation page accordingly?

[flixos90]

Replying to afercia:

That makes sense, but the documentation linked in this issue ​only mentions bundled themes.

I guess it's worth considering updating the documentation page accordingly?

I have already attempted that, see ​https://github.com/WordPress/wpcs-docs/pull/133. Looks like that PR needs a third opinion?