PHP 8.0 migration guide

[cmb69]

This is a follow-up to PR #164 which I've screwed up unrepairably.

[carusogabriel]

@sgolemon Wanna take a look as well?

[carusogabriel]

Should we document that all the deprecated stuff from PHP 7.x were removed as well?

php/php-src#3770

[cmb69]

Should we document that all the deprecated stuff from PHP 7.x were removed as well?

At least most of that should already be there in https://github.com/php/doc-en/pull/170/files#diff-dc046224091f8e12cac61d0f1373afa026a8425c1dac1032440080786e77f047. Might be sensible to double-check.

PS: I've checked php/php-src#3770, and added the missing "Defining a free-standing assert() function". All others should be already documented.

[cmb69]

The union type documentation would be available with PR #174.

[nikic]

I think we should merge this and continue iterating in-tree.

Only thing I'd suggest is to maybe merge the Windows section into appropriate other places. E.g. the proc_open one into incompatible changes, and the other two into other changes).

[cmb69]

Thanks, @nikic! However, I have some concerns to merge this wrt. translations. Even if we add a note to the commit message that this is work in progress and should not be translated yet, translators may overlook or ignore that, and might have a hard time to follow up on changes. And I'm afraid there is the need for a lot of changes; for instance, I've just noticed that PhD apperently does not support linking to arbitrary elements, so it seems that we need <sect3> elements instead of the <listitems> (or patch PhD), and that would require restructuring (and maybe also some reordering). At least linking to the most prominent features/changes should be possible (e.g. to link from the release announcements).

[cmb69]

I have added subsections for the most relevant changes, integrated the Windows section into incompatible, added a few links to documentation available in the meantime, and applied as http://svn.php.net/viewvc?view=revision&revision=351500.