Namespaced functions failing inside returned closure

[brentkelly]

Hi guys - found a bit of a curly one.

TLDR; clone this repo & run index.php: https://github.com/brentkelly/opis-closure-bug-demo/

Take the following scenario:

• You have namespaced functions, and a separate namespaced class in the same namespace.
• Inside the class, you generate a closure that references the namespaced function (without the full path because you are in the same namespace).
• Serialize & then unserialize that closure.
• On executing the closure you get a Call to undefined function fatal error.

Essentially - it loses track that the function call within the closure should be referencing the namespaced function - not the global scope. If you have a global function of the same name - it will call the global function instead of throwing the fatal error - producing potentially even more bizarre behavior :).

If you update the closure to instead reference the full function namespace path, everything then works smoothly.

Because there are a few moving parts, I've put together a quick repo demonstrating the behavior https://github.com/brentkelly/opis-closure-bug-demo/.

• The class \Services\Foo has methods that generate closures referencing the function \Services\foo() (inside /services/functions.php).
• index.php creates a closure with a full namespace reference to \Services\foo() and executes it, demonstrating it working fine.
• it then creates a closure relying the class being in the same \Services namespace, and executes it before & after serializing/unserializing.

The last approch shows it execute fine prior to serializing, but after serialize/unserialize it throws:

PHP Fatal error:  Uncaught Error: Call to undefined function foo() in closure://function($name) {
                        foo("Hello $name!");
                }:3
Stack trace:
#0 /home/brent/code/demos/promise-serialize-basic/index.php(41): Services\Foo::{closure}()
#1 {main}
  thrown in closure://function($name) {
                        foo("Hello $name!");
                } on line 3

Much respect for this project - its awesome.

[brentkelly]

FYI the real world scenario I've encountered this issue is attempting to meld opis/closure with reactphp/promise to get Promises that can be defined in one thread, and then resolved in another later thread.

It essentially plays pretty nicely - aside from this 1 issue. \React\Promise\Promise generates callbacks for resolving that call a namespaced resolve function. Given that I was doing this in a Laravel project, the issue I was encountering was it was attempting to call Laravel's global resolve function after unserializing the promise, rather than \React\Promise\resolve.

Here is a demo of this in action: https://github.com/brentkelly/serialized-promise-demo. You will see from the PR referenced in the README.md the exact lines in src/Promise.php (line 226 being the main culprit) causing the issue.

I was hoping to get them to work around the issue by referencing the full namespaced path on the function call but they're pushing back saying its a bug in opis/closure.

[sorinsarca]

@brentkelly instead of replacing every function call with the absolute form you could just import it once

namespace My\Ns;

use function My\Ns\my_func; // reference my_func once instead of replacing every function call

$f = function() {
   my_func();
   // ...
   my_func();
};

However a PR was submitted and probably this issue will be fixed in the next version.

[brentkelly]

Great - thanks for the reply @sorinsarca :).

Good suggestion re just using once - although still means I'd have to fork reactphp/promise.

Look forward to the next version.

[sorinsarca]

@brentkelly this issue is fixed in version 3.5.7 of opis/closure

[brentkelly]

@sorinsarca Brilliant - thanks!