Prevent void param type

Author: WoutervdBrink

lib/PhpParser/ParserAbstract.php

@@ -1078,6 +1078,13 @@ protected function checkParam(Param $node): void {
                 $node->default->getAttributes()
             ));
         }
+
+        if ($node->type instanceof Identifier && $node->type->name === 'void') {
+            $this->emitError(new Error(
+                'Parameter type cannot be void',
+                $node->type->getAttributes()
+            ));
+        }
     }
 
     protected function checkTryCatch(TryCatch $node): void {

test/code/parser/stmt/function/invalidVoidParam.test

@@ -0,0 +1,37 @@
+Invalid parameter with type void
+-----
+<?php
+function foo(void $foo) {}
+-----
+Parameter type cannot be void from 2:14 to 2:17
+array(
+    0: Stmt_Function(
+        attrGroups: array(
+        )
+        byRef: false
+        name: Identifier(
+            name: foo
+        )
+        params: array(
+            0: Param(
+                attrGroups: array(
+                )
+                flags: 0
+                type: Identifier(
+                    name: void
+                )
+                byRef: false
+                variadic: false
+                var: Expr_Variable(
+                    name: foo
+                )
+                default: null
+                hooks: array(
+                )
+            )
+        )
+        returnType: null
+        stmts: array(
+        )
+    )
+)

test/code/parser/stmt/function/validVoidParam.test

@@ -0,0 +1,37 @@
+Valid parameter with type void
+-----
+<?php
+function foo(void $foo) {}
+-----
+!!version=7.0
+array(
+    0: Stmt_Function(
+        attrGroups: array(
+        )
+        byRef: false
+        name: Identifier(
+            name: foo
+        )
+        params: array(
+            0: Param(
+                attrGroups: array(
+                )
+                flags: 0
+                type: Name(
+                    name: void
+                )
+                byRef: false
+                variadic: false
+                var: Expr_Variable(
+                    name: foo
+                )
+                default: null
+                hooks: array(
+                )
+            )
+        )
+        returnType: null
+        stmts: array(
+        )
+    )
+)