fix(optimizer): parenthesize null-check expressions

phpunit/code/assign-not-identical-null.php

@@ -0,0 +1,17 @@
+<?php
+
+class AssignedValueNullCheck
+{
+    public function check(): bool
+    {
+        if (!is_null($error = error_get_last()) && $this->isFatal($error['type'])) {
+            return true;
+        }
+        return false;
+    }
+
+    private function isFatal(int $type): bool
+    {
+        return $type > 0;
+    }
+}

phpunit/src/OperatorTest.php

@@ -22,6 +22,23 @@ class OperatorTest extends \BaseTest
         $this->assertStringContainsString('php::same(php::true_, value)', $cpp);
     }
 
+    public function testAssignedValueNotIdenticalToNullIsParenthesized(): void
+    {
+        global $translator;
+        $compiler = \TypePhp\CompilerTest::create(ROOT_PATH);
+        $translator = $compiler;
+        $testFile = __DIR__ . '/../code/assign-not-identical-null.php';
+        $compiler->addFiles([$testFile]);
+        $compiler->prepareFile($testFile);
+        $cppFile = $compiler->convertFile($testFile);
+        $cpp = file_get_contents($cppFile);
+
+        $this->assertMatchesRegularExpression(
+            '/!\(\(error = php::call\([^\n]+\)\)\.isNull\(\)\)/',
+            $cpp,
+        );
+    }
+
     public function testLiteralIntDivideByZeroDoesNotCompile(): void
     {
         $this->exec('Cannot divide or modulo by zero', 'divide-by-zero-int.php');

src/Optimizer/FuncCallOptimizer.php

@@ -612,7 +612,7 @@ trait FuncCallOptimizer
 
     protected function genIsNull(string $n, Node\Expr\FuncCall $e, array $c): string
     {
-        return $this->parseIdentifier($e->args[0]->value) . '.isNull()';
+        return '(' . $this->parseExprAsValue($e->args[0]->value) . ').isNull()';
     }
 
     protected function genIsCallable(string $n, Node\Expr\FuncCall $e, array $c): string|false

src/Parser/BinaryOpTrait.php

@@ -388,7 +388,10 @@ trait BinaryOpTrait
         $left  = $this->parseCompareExpr($expr->left);
         $right = $this->parseCompareExpr($expr->right);
         if ($right === 'nullptr') {
-            return $left . '.isNull()';
+            // The left operand may itself be an assignment or another compound
+            // expression. Parenthesize it before invoking Variant::isNull(), or
+            // C++ binds the member access to the assignment's RHS instead.
+            return '(' . $left . ').isNull()';
         }
         if ($optimized = $this->optimizeIdenticalOp($expr->left, $expr->right, $left, $right)) {
             return $optimized;