diff --git a/phpunit/code/inheritance_error_final_method.php b/phpunit/code/inheritance_error_final_method.php
new file mode 100644
index 00000000..b2f62163
--- /dev/null
+++ b/phpunit/code/inheritance_error_final_method.php
@@ -0,0 +1,15 @@
+<?php
+
+class InheritanceFinalMethodParent
+{
+    final public function run(): void
+    {
+    }
+}
+
+class InheritanceFinalMethodChild extends InheritanceFinalMethodParent
+{
+    public function run(): void
+    {
+    }
+}
diff --git a/phpunit/code/inheritance_error_param_covariant_class.php b/phpunit/code/inheritance_error_param_covariant_class.php
new file mode 100644
index 00000000..e8a2b12a
--- /dev/null
+++ b/phpunit/code/inheritance_error_param_covariant_class.php
@@ -0,0 +1,23 @@
+<?php
+
+class InheritanceParamCovariantParentType
+{
+}
+
+class InheritanceParamCovariantChildType extends InheritanceParamCovariantParentType
+{
+}
+
+class InheritanceParamCovariantParent
+{
+    public function handle(InheritanceParamCovariantParentType $value): void
+    {
+    }
+}
+
+class InheritanceParamCovariantChild extends InheritanceParamCovariantParent
+{
+    public function handle(InheritanceParamCovariantChildType $value): void
+    {
+    }
+}
diff --git a/phpunit/code/inheritance_error_return_contravariant_class.php b/phpunit/code/inheritance_error_return_contravariant_class.php
new file mode 100644
index 00000000..1a771570
--- /dev/null
+++ b/phpunit/code/inheritance_error_return_contravariant_class.php
@@ -0,0 +1,25 @@
+<?php
+
+class InheritanceReturnContravariantParentType
+{
+}
+
+class InheritanceReturnContravariantChildType extends InheritanceReturnContravariantParentType
+{
+}
+
+class InheritanceReturnContravariantParent
+{
+    public function make(): InheritanceReturnContravariantChildType
+    {
+        return new InheritanceReturnContravariantChildType();
+    }
+}
+
+class InheritanceReturnContravariantChild extends InheritanceReturnContravariantParent
+{
+    public function make(): InheritanceReturnContravariantParentType
+    {
+        return new InheritanceReturnContravariantParentType();
+    }
+}
diff --git a/phpunit/code/inheritance_parameter_type_contravariant_class.php b/phpunit/code/inheritance_parameter_type_contravariant_class.php
new file mode 100644
index 00000000..a58af7dc
--- /dev/null
+++ b/phpunit/code/inheritance_parameter_type_contravariant_class.php
@@ -0,0 +1,23 @@
+<?php
+
+class InheritanceParamContravariantParentType
+{
+}
+
+class InheritanceParamContravariantChildType extends InheritanceParamContravariantParentType
+{
+}
+
+class InheritanceParamContravariantParent
+{
+    public function handle(InheritanceParamContravariantChildType $value): void
+    {
+    }
+}
+
+class InheritanceParamContravariantChild extends InheritanceParamContravariantParent
+{
+    public function handle(InheritanceParamContravariantParentType $value): void
+    {
+    }
+}
diff --git a/phpunit/code/inheritance_return_type_covariant_class.php b/phpunit/code/inheritance_return_type_covariant_class.php
new file mode 100644
index 00000000..bc2b9464
--- /dev/null
+++ b/phpunit/code/inheritance_return_type_covariant_class.php
@@ -0,0 +1,25 @@
+<?php
+
+class InheritanceReturnCovariantParentType
+{
+}
+
+class InheritanceReturnCovariantChildType extends InheritanceReturnCovariantParentType
+{
+}
+
+class InheritanceReturnCovariantParent
+{
+    public function make(): InheritanceReturnCovariantParentType
+    {
+        return new InheritanceReturnCovariantParentType();
+    }
+}
+
+class InheritanceReturnCovariantChild extends InheritanceReturnCovariantParent
+{
+    public function make(): InheritanceReturnCovariantChildType
+    {
+        return new InheritanceReturnCovariantChildType();
+    }
+}
diff --git a/phpunit/code/inheritance_return_type_covariant_from_none.php b/phpunit/code/inheritance_return_type_covariant_from_none.php
new file mode 100644
index 00000000..52c955c6
--- /dev/null
+++ b/phpunit/code/inheritance_return_type_covariant_from_none.php
@@ -0,0 +1,17 @@
+<?php
+
+class InheritanceReturnNoneParent
+{
+    public function run()
+    {
+        return 1;
+    }
+}
+
+class InheritanceReturnNoneChild extends InheritanceReturnNoneParent
+{
+    public function run(): int
+    {
+        return 1;
+    }
+}
diff --git a/phpunit/src/InheritanceErrorTest.php b/phpunit/src/InheritanceErrorTest.php
index 26c28257..ab54eac6 100644
--- a/phpunit/src/InheritanceErrorTest.php
+++ b/phpunit/src/InheritanceErrorTest.php
@@ -48,6 +48,16 @@ class InheritanceErrorTest extends TestCase
         $this->exec('must be compatible', 'inheritance_error_return.php');
     }
 
+    public function testReturnTypeCannotBeContravariant()
+    {
+        $this->exec('must be compatible', 'inheritance_error_return_contravariant_class.php');
+    }
+
+    public function testParameterTypeCannotBeCovariant()
+    {
+        $this->exec('must be compatible', 'inheritance_error_param_covariant_class.php');
+    }
+
     public function testByRefMismatch()
     {
         $this->exec('must be compatible', 'inheritance_error_byref.php');
@@ -73,6 +83,11 @@ class InheritanceErrorTest extends TestCase
         $this->exec('must be compatible', 'inheritance_error_static.php');
     }
 
+    public function testCannotOverrideFinalMethod()
+    {
+        $this->exec('Cannot override final method', 'inheritance_error_final_method.php');
+    }
+
     public function testInterfaceMethodStaticMismatch()
     {
         $this->exec('must be compatible', 'interface_method_static_mismatch.php');
@@ -83,6 +98,21 @@ class InheritanceErrorTest extends TestCase
         $this->assertCompiles('inheritance_optional_param_allowed.php');
     }
 
+    public function testChildMayDeclareReturnTypeWhenParentHasNone()
+    {
+        $this->assertCompiles('inheritance_return_type_covariant_from_none.php');
+    }
+
+    public function testChildReturnTypeMayBeCovariant()
+    {
+        $this->assertCompiles('inheritance_return_type_covariant_class.php');
+    }
+
+    public function testChildParameterTypeMayBeContravariant()
+    {
+        $this->assertCompiles('inheritance_parameter_type_contravariant_class.php');
+    }
+
     public function testPropertyTypeMismatch()
     {
         $this->exec('must be compatible', 'inheritance_error_prop_type.php');
diff --git a/src/Php/Translator.php b/src/Php/Translator.php
index 7a69a90e..cfe04d6c 100644
--- a/src/Php/Translator.php
+++ b/src/Php/Translator.php
@@ -3159,9 +3159,13 @@ CODE;
             }
             // 父类是内置类
             if ($classDef->inheritedFromInternalClass) {
-                if (Reflection::getClassMethodModifiers($extends, $name) & \ReflectionMethod::IS_PRIVATE) {
+                $modifiers = Reflection::getClassMethodModifiers($extends, $name);
+                if ($modifiers & \ReflectionMethod::IS_PRIVATE) {
                     goto _error;
                 }
+                if ($modifiers & \ReflectionMethod::IS_FINAL) {
+                    goto _final_error;
+                }
                 break;
             }
             $classDef = $this->getClass($extends);
@@ -3173,6 +3177,12 @@ CODE;
                         'Cannot override private method `' .
                         $extends . '::' . $name . '()`');
                 }
+                if ($methodDef->flags & Modifiers::FINAL) {
+                    _final_error:
+                    $this->fatalError($v,
+                        'Cannot override final method `' .
+                        $extends . '::' . $name . '()`');
+                }
                 $this->validateMethodOverrideSignature($v, $name, $this->methodDef, $methodDef, $extends);
                 break;
             }
@@ -3213,9 +3223,7 @@ CODE;
             return;
         }
 
-        // Compare return type
-        if ($childFuncDef->returnType !== $parentFuncDef->returnType ||
-            $childFuncDef->returnClass !== $parentFuncDef->returnClass) {
+        if (!$this->isReturnTypeOverrideCompatible($childFuncDef, $parentFuncDef)) {
             $error('return type mismatch');
         }
 
@@ -3231,7 +3239,7 @@ CODE;
                 $error("missing parameter #{$i}");
             }
             $childArg = $childFuncDef->argInfoList[$i];
-            if ($childArg->type !== $parentArg->type || $childArg->class !== $parentArg->class) {
+            if (!$this->isParameterTypeOverrideCompatible($childArg, $parentArg)) {
                 $error("parameter #{$i} type mismatch");
             }
             if ($childArg->byRef !== $parentArg->byRef) {
@@ -3251,6 +3259,61 @@ CODE;
         }
     }
 
+    private function isReturnTypeOverrideCompatible(FunctionDef $childFuncDef, FunctionDef $parentFuncDef): bool
+    {
+        if ($parentFuncDef->returnTypeUndeclared) {
+            return true;
+        }
+        if ($childFuncDef->returnTypeUndeclared) {
+            return false;
+        }
+        if ($parentFuncDef->returnTypeCheck || $childFuncDef->returnTypeCheck) {
+            return $parentFuncDef->returnTypeStr === $childFuncDef->returnTypeStr;
+        }
+        if ($parentFuncDef->returnType === self::TYPE_VAR) {
+            return true;
+        }
+        if ($childFuncDef->returnType !== $parentFuncDef->returnType) {
+            return false;
+        }
+        if ($parentFuncDef->returnType !== self::TYPE_OBJECT) {
+            return true;
+        }
+        if ($childFuncDef->returnClass === $parentFuncDef->returnClass) {
+            return true;
+        }
+        if (!$childFuncDef->returnClass || !$parentFuncDef->returnClass) {
+            return false;
+        }
+        return $this->isInheritedFrom($childFuncDef->returnClass, $parentFuncDef->returnClass);
+    }
+
+    private function isParameterTypeOverrideCompatible(ArgInfo $childArg, ArgInfo $parentArg): bool
+    {
+        if ($parentArg->typeCheck || $childArg->typeCheck) {
+            return $parentArg->typeStr === $childArg->typeStr;
+        }
+        if ($childArg->undeclared || $childArg->type === self::TYPE_VAR) {
+            return true;
+        }
+        if ($parentArg->undeclared || $parentArg->type === self::TYPE_VAR) {
+            return false;
+        }
+        if ($childArg->type !== $parentArg->type) {
+            return false;
+        }
+        if ($parentArg->type !== self::TYPE_OBJECT) {
+            return true;
+        }
+        if ($childArg->class === $parentArg->class) {
+            return true;
+        }
+        if (!$childArg->class || !$parentArg->class) {
+            return false;
+        }
+        return $this->isInheritedFrom($parentArg->class, $childArg->class);
+    }
+
     private function checkInterfaceImplementations(Node\Stmt\Class_|Node\Stmt\Enum_ $classStmt): void
     {
         $classDef = $this->classDef;