diff --git a/src/CompilerBase.php b/src/CompilerBase.php
index 074a1517..fab95bf8 100644
--- a/src/CompilerBase.php
+++ b/src/CompilerBase.php
@@ -1017,7 +1017,10 @@ class CompilerBase implements PropertyAccessContext
 
     protected function getFullClassName(): string
     {
-        return ltrim($this->namespace . '\\' . $this->class, '\\');
+        // 在接口上下文中，$this->class 为空但 $this->interface 已设置，
+        // `self` 类型声明应解析为接口自身的完整名称。
+        $classLike = $this->class !== '' ? $this->class : $this->interface;
+        return ltrim($this->namespace . '\\' . $classLike, '\\');
     }
 
     protected function getFullMethodName(string $fullClassName, string $method): string
diff --git a/tests/compiler/class/interface-method-self-return.phpt b/tests/compiler/class/interface-method-self-return.phpt
new file mode 100644
index 00000000..90e44eab
--- /dev/null
+++ b/tests/compiler/class/interface-method-self-return.phpt
@@ -0,0 +1,42 @@
+--TEST--
+interface method with `self` return type implemented by class (fluent interface), and namespace block containing comments
+--FILE--
+<?php
+
+namespace {
+    interface TestInterface
+    {
+        public function get(): self;
+    }
+
+    class TestClass implements TestInterface
+    {
+        public int $value = 0;
+
+        public function get(): self
+        {
+            return $this;
+        }
+
+        public function setValue(int $value): self
+        {
+            $this->value = $value;
+            return $this;
+        }
+    }
+
+    function main()
+    {
+        $test = new TestClass;
+        // get() returns self, so the result still satisfies the interface
+        var_dump($test->get() instanceof TestInterface);
+        var_dump($test === $test->get());
+        // fluent chaining of self-returning methods
+        var_dump($test->get()->setValue(42)->value);
+    }
+}
+?>
+--EXPECT--
+bool(true)
+bool(true)
+int(42)
diff --git a/tests/compiler/namespace/interface-self-return-namespaced.phpt b/tests/compiler/namespace/interface-self-return-namespaced.phpt
new file mode 100644
index 00000000..cfda0bad
--- /dev/null
+++ b/tests/compiler/namespace/interface-self-return-namespaced.phpt
@@ -0,0 +1,36 @@
+--TEST--
+interface method `self` return type resolves to the interface's fully-qualified name inside a named namespace
+--FILE--
+<?php
+
+namespace App {
+    interface Chainable
+    {
+        public function chain(): self;
+    }
+
+    // comment inside a named namespace block (Stmt_Nop)
+    class Widget implements Chainable
+    {
+        public array $log = [];
+
+        public function chain(): self
+        {
+            $this->log[] = 'chain';
+            return $this;
+        }
+    }
+}
+
+namespace {
+    function main()
+    {
+        $w = new \App\Widget();
+        var_dump($w->chain()->chain() instanceof \App\Chainable);
+        var_dump(count($w->log));
+    }
+}
+?>
+--EXPECT--
+bool(true)
+int(2)