Removed warning about missing namespace leading backslash in `var_export()` docs

[Ocramius]

var_export() needs to prefix classes it references with \, because its code could be transplanted in any source location/namespace, so the assumption of it being used only in the context of the root namespace is not sufficient.

For example, in a code snippet like following ( https://3v4l.org/4mONc ):

<?php

class SomeObject {}
var_export([new SomeObject]);

This should produce:

array (
  0 => 
  \SomeObject::__set_state(array(
  )),
)

Userland should not concern itself with the contents of the var_export()-produced code snippets, and use them as-is instead.

Ref: https://github.com/php/php-src/pull/8232 Ref: https://github.com/php/php-src/pull/8233 Ref: https://github.com/Ocramius/ProxyManager/issues/754

[cmb69]

Hmm, but see https://externals.io/message/67008#67010. ;)

[Ocramius]

Aye, mistakes were made :|

Indeed confusing scope on my end:

• serialize() provides a value inside a string, hence always global namespace
• var_export() provides a code snippet, hence contextual to execution scope

Sorry for my previous mistake on that: my idea of var_export() was indeed broken.

See also https://github.com/php/php-src/pull/8233#issuecomment-1073961831

[guilliamxavier]

Should probably also add a row in the Changelog, and update Examples, as was done in https://github.com/php/doc-en/compare/68601c39b9543a3d848e01f90f1fbb5512f39929%5E...9ddc8b69468da104704dadf9fb8d22480c7ad687?

[Ocramius]

Thanks @guilliamxavier: will try emulating that patch here, once https://github.com/php/php-src/pull/8233 is merged

[Girgias]

This feels like it needs a changelog entry for 8.2 to explain the change (and also added to the migration guide/UPGRADING file, as that somehow didn't get done, so the change got missed).

Otherwise, I don't really mind dropping it, but I think it may be useful to have it somewhere that details the nuance and pitfall.

[cmb69]

I just landed https://github.com/php/doc-en/commit/0f27fadf81b66268edf545f13891401b4d53cc38, so this ticket can be closed. Thanks everybody!