Indicates whether a variable is global

[cedric-anne]

This will permit to easilly assign types to global variables in an extension. Without this change, it is not possible to distinguish local variables from global variables.

Related to https://github.com/phpstan/phpstan/issues/13243 and following a discussion in #4233.

Here is an exemple:

<?php

namespace MyPhpstanExtension;

use PhpParser\Node\Expr;
use PhpParser\Node\Expr\Variable;
use PHPStan\Analyser\Scope;
use PHPStan\Type\ObjectType;
use PHPStan\Type\ExpressionTypeResolverExtension;
use PHPStan\Type\Type;

class GlobalExpressionTypeResolverExtension implements ExpressionTypeResolverExtension
{

	public function getType(Expr $expr, Scope $scope): ?Type
	{
		if (!$expr instanceof Variable || !$scope->isGlobalVariable($expr->name)) {
			return null;
		}

		if ($expr->name === 'DB') {
			return new ObjectType(\App\Db::class);
		}

		return null;
	}
}

[cedric-anne]

1. You're not testing what this should be allowing you. In the original issue you're saying you want to override variable types with ExpressionTypeResolverExtension but you're not testing that here.

I added a test for this use case.

2. Instead of setting an attribute on Variable in assignVariable, I'm thinking we could call assignExpression [...] with new virtual node GlobalVariableExpr. The Scope::isGlobalVariable could check the type of the expr node for that.

I struggle to find how to make it work, probably because I am not familiar with the PHPStan internal logic, so maybe I missed something.

I finally found a solution with an early call to the ExpressionTypeResolverExtensionRegistry here: https://github.com/phpstan/phpstan-src/blob/db78deb7255de62d0d253d7cfd901c91b65b58e3/src/Analyser/MutatingScope.php#L4292-L4301

This is the only solution I found to be able to assign the type during the Global_ statement node parsing.

[VincentLanglet]

I think you need to rebase/fix some conflict @cedric-anne

[cedric-anne]

I think you need to rebase/fix some conflict @cedric-anne

Done. Conflicts were only related to use statements.

I am not entirely satisfied with what I have proposed, but I was waiting for a review from someone who knows more about the internal logic of PHPStan to find out if I had missed something obvious, or even if I was heading in the right direction. Rather than using the ExpressionTypeResolverExtension extensions, I think it might be better to declare a new extension interface GlobalVariableTypeSpecifyingExtension with a public function getGlobalVariableType(GlobalVariableExpr $globalVariable, Scope $scope): ?Type method.

Also, maybe this should be splitted into two distinct PRs. Indeed, being able to know whether a variable is global and being able to define its type using an extension are two distinct features.