fix gh-41: preserve assignment method receivers

src/Parser/MethodCallTrait.php

@@ -457,6 +457,13 @@ trait MethodCallTrait
             $object = empty($expr->args)
                 ? $this->parseIdentifier($expr->var)
                 : $this->parseOrderedOperand($expr->var, false);
+            // Preserve the receiver expression boundary for no-argument
+            // calls. Without these parentheses, C++ member access binds more
+            // tightly than assignment, so `($b = $a)->method()` was emitted
+            // as `b = a.call(...)` instead of `(b = a).call(...)`.
+            if (empty($expr->args) && !$this->isVarExpr($expr->var)) {
+                $object = '(' . $object . ')';
+            }
         }
         if ($this->isVarExpr($expr->var)) {
             if (!$this->hasVar($object)) {

tests/compiler/dynamic_call/assignment-expression-receiver.phpt

@@ -0,0 +1,105 @@
+--TEST--
+Assignment expressions used as method receivers preserve PHP evaluation semantics
+--FILE--
+<?php
+
+class AssignmentReceiver
+{
+    public string $value;
+
+    public function __construct(string $value)
+    {
+        $this->value = $value;
+    }
+
+    public function id(): string
+    {
+        return $this->value;
+    }
+
+    public function append(string $suffix): string
+    {
+        return $this->value . $suffix;
+    }
+}
+
+class AssignmentReceiverFactory extends AssignmentReceiver
+{
+    public static function fromSelf(): string
+    {
+        return ($receiver = new self('self'))->id();
+    }
+
+    public static function fromStatic(): string
+    {
+        return ($receiver = new static('static'))->id();
+    }
+}
+
+class AssignmentReceiverChild extends AssignmentReceiverFactory
+{
+}
+
+class AssignmentReceiverHolder
+{
+    public AssignmentReceiver $receiver;
+
+    public function __construct(AssignmentReceiver $receiver)
+    {
+        $this->receiver = $receiver;
+    }
+}
+
+function makeAssignmentReceiver(int &$calls, string $value): AssignmentReceiver
+{
+    ++$calls;
+    return new AssignmentReceiver($value);
+}
+
+function main(): void
+{
+    $original = new AssignmentReceiver('base');
+
+    echo ($assigned = $original)->id(), "\n";
+    var_dump($assigned === $original);
+
+    // A call with arguments already materializes its receiver; retain it as a
+    // control for the no-argument path fixed by this regression.
+    echo ($withArgument = $original)->append('-arg'), "\n";
+
+    $calls = 0;
+    echo ($created = makeAssignmentReceiver($calls, 'factory'))->id(), "\n";
+    var_dump($calls);
+    echo $created->id(), "\n";
+
+    echo AssignmentReceiverFactory::fromSelf(), "\n";
+    echo AssignmentReceiverChild::fromStatic(), "\n";
+
+    $holder = new AssignmentReceiverHolder($original);
+    echo ($holder->receiver = new AssignmentReceiver('property'))->id(), "\n";
+
+    $items = [];
+    echo ($items[0] = new AssignmentReceiver('array'))->id(), "\n";
+
+    echo ($left = $right = new AssignmentReceiver('chain'))->id(), "\n";
+    var_dump($left === $right);
+
+    echo ($reference =& $original)->id(), "\n";
+    var_dump($reference === $original);
+}
+?>
+--EXPECT--
+base
+bool(true)
+base-arg
+factory
+int(1)
+factory
+self
+static
+property
+array
+chain
+bool(true)
+base
+bool(true)