PHP 7.1: Add void+iterable support

In PHP 7 mode, these will now be represented as strings 'void'
and 'iterable'.

grammar/php7.y

@@ -364,7 +364,7 @@ parameter:
 ;
 
 type:
-      name                                                  { $$ = $this->handleScalarTypes($1); }
+      name                                                  { $$ = $this->handleBuiltinTypes($1); }
     | T_ARRAY                                               { $$ = 'array'; }
     | T_CALLABLE                                            { $$ = 'callable'; }
 ;

lib/PhpParser/Parser/Php7.php

@@ -1677,7 +1677,7 @@ class Php7 extends \PhpParser\ParserAbstract
     }
 
     protected function reduceRule221() {
-         $this->semValue = $this->handleScalarTypes($this->semStack[$this->stackPos-(1-1)]);
+         $this->semValue = $this->handleBuiltinTypes($this->semStack[$this->stackPos-(1-1)]);
     }
 
     protected function reduceRule222() {

lib/PhpParser/ParserAbstract.php

@@ -481,12 +481,14 @@ abstract class ParserAbstract implements Parser
         return $style;
     }
 
-    protected function handleScalarTypes(Name $name) {
+    protected function handleBuiltinTypes(Name $name) {
         $scalarTypes = [
-            'bool'   => true,
-            'int'    => true,
-            'float'  => true,
-            'string' => true,
+            'bool'     => true,
+            'int'      => true,
+            'float'    => true,
+            'string'   => true,
+            'iterable' => true,
+            'void'     => true,
         ];
 
         if (!$name->isUnqualified()) {

test/code/parser/stmt/function/builtinTypeDeclarations.test

@@ -1,7 +1,7 @@
 Scalar type declarations
 -----
 <?php
-function test(bool $a, Int $b, FLOAT $c, StRiNg $d) {}
+function test(bool $a, Int $b, FLOAT $c, StRiNg $d, iterable $e) : void {}
 -----
 !!php7
 array(
@@ -37,8 +37,15 @@ array(
                 name: d
                 default: null
             )
+            4: Param(
+                type: iterable
+                byRef: false
+                variadic: false
+                name: e
+                default: null
+            )
         )
-        returnType: null
+        returnType: void
         stmts: array(
         )
     )