Phan\AST\UnionTypeVisitor::visitCall PHP Method

    public function visitCall(Node $node) : UnionType
    {
        // Things like `$func()`. We don't understand these.
        if ($node->children['expr']->kind !== \ast\AST_NAME) {
            return new UnionType();
        }
        $function_name = $node->children['expr']->children['name'];
        try {
            $function = (new ContextNode($this->code_base, $this->context, $node->children['expr']))->getFunction($function_name);
        } catch (CodeBaseException $exception) {
            // If the function wasn't declared, it'll be caught
            // and reported elsewhere
            return new UnionType();
        }
        $function_fqsen = $function->getFQSEN();
        // TODO: I don't believe we need this any more
        // If this is an internal function, see if we can get
        // its types from the static dataset.
        if ($function->isInternal() && $function->getUnionType()->isEmpty()) {
            $map = UnionType::internalFunctionSignatureMapForFQSEN($function->getFQSEN());
            return $map[$function_name] ?? new UnionType();
        }
        return $function->getUnionType();
    }