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 phpstan/phpstan#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;
	}
}

[ondrejmirtes]

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.
2. Instead of setting an attribute on Variable in assignVariable, I'm thinking we could call assignExpression here

   phpstan-src/src/Analyser/NodeScopeResolver.php

   Line 1970 in 70a039f

   $scope = $scope->assignVariable($var->name, new MixedType(), new MixedType(), TrinaryLogic::createYes());

   with new virtual node GlobalVariableExpr. The Scope::isGlobalVariable could check the type of the expr node for that.

Existing virtual expr nodes are defined here: https://github.com/phpstan/phpstan-src/tree/2.1.x/src/Node/Expr

Additionally, they have to be handled here https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Node/Printer/Printer.php and here

phpstan-src/src/Analyser/MutatingScope.php

Lines 739 to 753 in 70a039f

	if ($node instanceof GetIterableKeyTypeExpr) {
	return $this->getIterableKeyType($this->getType($node->getExpr()));
	}
	if ($node instanceof GetIterableValueTypeExpr) {
	return $this->getIterableValueType($this->getType($node->getExpr()));
	}
	if ($node instanceof GetOffsetValueTypeExpr) {
	return $this->getType($node->getVar())->getOffsetValueType($this->getType($node->getDim()));
	}
	if ($node instanceof ExistingArrayDimFetch) {
	return $this->getType(new Expr\ArrayDimFetch($node->getVar(), $node->getDim()));
	}
	if ($node instanceof UnsetOffsetExpr) {
	return $this->getType($node->getVar())->unsetOffset($this->getType($node->getDim()));
	}

.