PHPStan\Rules\Classes\ClassConstantRule::processNode PHP Method

    public function processNode(Node $node, Scope $scope) : array
    {
        $class = $node->class;
        if ($class instanceof \PhpParser\Node\Name) {
            $className = (string) $class;
        } else {
            $classType = $scope->getType($class);
            if ($classType->getClass() !== null) {
                $className = $classType->getClass();
            } else {
                return [];
            }
        }
        if ($className === 'self' || $className === 'static') {
            if ($scope->getClass() === null && !$scope->isInAnonymousClass()) {
                return [sprintf('Using %s outside of class scope.', $className)];
            }
            if ($className === 'static') {
                return [];
            }
            if ($className === 'self') {
                $className = $scope->getClass();
            }
        }
        $constantName = $node->name;
        if ($scope->getClass() !== null && $className === 'parent') {
            $currentClassReflection = $this->broker->getClass($scope->getClass());
            if ($currentClassReflection->getParentClass() === false) {
                return [sprintf('Access to parent::%s but %s does not extend any class.', $constantName, $scope->getClass())];
            }
            $className = $currentClassReflection->getParentClass()->getName();
        }
        if (!$this->broker->hasClass($className)) {
            return [sprintf('Class %s not found.', $className)];
        }
        if ($constantName === 'class') {
            return [];
        }
        $classReflection = $this->broker->getClass($className);
        if (!$classReflection->hasConstant($constantName)) {
            return [sprintf('Access to undefined constant %s::%s.', $classReflection->getName(), $constantName)];
        }
        $constantReflection = $classReflection->getConstant($constantName);
        if (!$scope->canAccessConstant($constantReflection)) {
            return [sprintf('Cannot access constant %s::%s from current scope.', $constantReflection->getDeclaringClass()->getName(), $constantName)];
        }
        return [];
    }