Properly handle new/instanceof operand restrictions

Fixes #912.

(cherry picked from commit 1eb6b56)

lib/PhpParser/PrettyPrinter/Standard.php

@@ -1077,9 +1077,12 @@ protected function pCallLhs(Node $node) {
         }
     }
 
-    protected function pNewVariable(Node $node) {
-        // TODO: This is not fully accurate.
-        return $this->pDereferenceLhs($node);
+    protected function pNewVariable(Node $node): string {
+        if (!$this->newOperandRequiresParens($node)) {
+            return $this->p($node);
+        } else {
+            return '(' . $this->p($node) . ')';
+        }
     }
 
     /**

lib/PhpParser/PrettyPrinterAbstract.php

@@ -1070,6 +1070,22 @@ protected function dereferenceLhsRequiresParens(Node $node) : bool {
             || $node instanceof Expr\ClassConstFetch);
     }
 
+    /**
+     * Determines whether an expression used in "new" or "instanceof" requires parentheses.
+     *
+     * @param Node $node New or instanceof operand
+     *
+     * @return bool Whether parentheses are required
+     */
+    protected function newOperandRequiresParens(Node $node): bool {
+        return !($node instanceof Node\Name
+            || $node instanceof Expr\Variable
+            || $node instanceof Expr\ArrayDimFetch
+            || $node instanceof Expr\PropertyFetch
+            || $node instanceof Expr\NullsafePropertyFetch
+            || $node instanceof Expr\StaticPropertyFetch);
+    }
+
     /**
      * Print modifiers, including trailing whitespace.
      *

test/code/prettyPrinter/expr/newVariable.test

@@ -2,10 +2,16 @@ Parentheses for complex new/instanceof expressions
 -----
 <?php
 new ('a' . 'b');
+new (x);
+new (foo());
+new ('foo');
 $x instanceof ('a' . 'b');
 $x instanceof ($y++);
 -----
 !!php7
 new ('a' . 'b')();
+new (x)();
+new (foo())();
+new ('foo')();
 $x instanceof ('a' . 'b');
-$x instanceof ($y++);
+$x instanceof ($y++);