Properly handle new/instanceof operand restrictions

Fixes #912.

lib/PhpParser/PrettyPrinter/Standard.php

@@ -414,7 +414,7 @@ protected function pExpr_Instanceof(Expr\Instanceof_ $node): string {
         list($precedence, $associativity) = $this->precedenceMap[Expr\Instanceof_::class];
         return $this->pPrec($node->expr, $precedence, $associativity, -1)
              . ' instanceof '
-             . $this->pNewVariable($node->class);
+             . $this->pNewOperand($node->class);
     }
 
     // Unary expressions
@@ -671,7 +671,7 @@ protected function pExpr_New(Expr\New_ $node): string {
             $args = $node->args ? '(' . $this->pMaybeMultiline($node->args) . ')' : '';
             return 'new ' . $this->pClassCommon($node->class, $args);
         }
-        return 'new ' . $this->pNewVariable($node->class)
+        return 'new ' . $this->pNewOperand($node->class)
             . '(' . $this->pMaybeMultiline($node->args) . ')';
     }
 
@@ -1086,9 +1086,12 @@ protected function pCallLhs(Node $node): string {
         }
     }
 
-    protected function pNewVariable(Node $node): string {
-        // TODO: This is not fully accurate.
-        return $this->pDereferenceLhs($node);
+    protected function pNewOperand(Node $node): string {
+        if (!$this->newOperandRequiresParens($node)) {
+            return $this->p($node);
+        } else {
+            return '(' . $this->p($node) . ')';
+        }
     }
 
     /**

lib/PhpParser/PrettyPrinterAbstract.php

@@ -1078,6 +1078,22 @@ 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

@@ -2,9 +2,15 @@ Parentheses for complex new/instanceof expressions
 -----
 <?php
 new ('a' . 'b');
+new (x);
+new (foo());
+new ('foo');
 $x instanceof ('a' . 'b');
 $x instanceof ($y++);
 -----
 new ('a' . 'b')();
+new (x)();
+new (foo())();
+new ('foo')();
 $x instanceof ('a' . 'b');
-$x instanceof ($y++);
+$x instanceof ($y++);