diff --git a/Zend/tests/friends/001.phpt b/Zend/tests/friends/001.phpt
deleted file mode 100644
index 3a1148f562bb0..0000000000000
--- a/Zend/tests/friends/001.phpt
+++ /dev/null
@@ -1,8 +0,0 @@
---TEST--
-Circular Friendship
---FILE--
-<?php
-class A for A,B {}
-?>
---EXPECTF--
-Fatal error: Class A may not be friends with itself in %s/001.php on line %d
diff --git a/Zend/tests/friends/002.phpt b/Zend/tests/friends/002.phpt
deleted file mode 100644
index 94ce708d06d7a..0000000000000
--- a/Zend/tests/friends/002.phpt
+++ /dev/null
@@ -1,10 +0,0 @@
---TEST--
-Circular Friendship Parent
---FILE--
-<?php
-class A for B {}
-
-class B for A extends A {}
-?>
---EXPECTF--
-Fatal error: Class B may not be friends with parent A in %s/002.php on line %d
diff --git a/Zend/tests/friends/003.phpt b/Zend/tests/friends/003.phpt
deleted file mode 100644
index 01cfe68d09d7f..0000000000000
--- a/Zend/tests/friends/003.phpt
+++ /dev/null
@@ -1,11 +0,0 @@
---TEST--
-No Friendship
---FILE--
-<?php
-class A for B {}
-
-class C extends A {}
-?>
---EXPECTF--
-Fatal error: Class C is not a friend of A in %s/003.php on line %d
-
diff --git a/Zend/tests/friends/004.phpt b/Zend/tests/friends/004.phpt
deleted file mode 100644
index e6721e44984f0..0000000000000
--- a/Zend/tests/friends/004.phpt
+++ /dev/null
@@ -1,21 +0,0 @@
---TEST--
-Friendship
---FILE--
-<?php
-class A for B {}
-
-class B extends A {}
-
-foreach ([A::class, B::class] as $class) {
-    $reflector = new ReflectionClass($class);
-    
-    var_dump($reflector->getFriendNames());
-}
-?>
---EXPECT--
-array(1) {
-  [0]=>
-  string(1) "B"
-}
-array(0) {
-}
diff --git a/Zend/tests/friends/005.phpt b/Zend/tests/friends/005.phpt
deleted file mode 100644
index 4cc7acf81c5a0..0000000000000
--- a/Zend/tests/friends/005.phpt
+++ /dev/null
@@ -1,26 +0,0 @@
---TEST--
-Friendship Inheritance
---FILE--
-<?php
-class A for B,C {}
-
-class B extends A {}
-
-foreach ([A::class, B::class] as $class) {
-    $reflector = new ReflectionClass($class);
-    
-    var_dump($reflector->getFriendNames());
-}
-?>
---EXPECT--
-array(2) {
-  [0]=>
-  string(1) "B"
-  [1]=>
-  string(1) "C"
-}
-array(1) {
-  [0]=>
-  string(1) "C"
-}
-
diff --git a/Zend/tests/friends/006.phpt b/Zend/tests/friends/006.phpt
deleted file mode 100644
index f5bff4a2fbf7d..0000000000000
--- a/Zend/tests/friends/006.phpt
+++ /dev/null
@@ -1,8 +0,0 @@
---TEST--
-Circular Friendship Interface
---FILE--
-<?php
-interface A for A,B {}
-?>
---EXPECTF--
-Fatal error: Interface A may not be friends with itself in %s/006.php on line %d
diff --git a/Zend/tests/friends/007.phpt b/Zend/tests/friends/007.phpt
deleted file mode 100644
index 0e44f02370faf..0000000000000
--- a/Zend/tests/friends/007.phpt
+++ /dev/null
@@ -1,10 +0,0 @@
---TEST--
-Circular Friendship Parent Interface
---FILE--
-<?php
-interface A for B {}
-
-interface B for A extends A {}
-?>
---EXPECTF--
-Fatal error: Interface B may not be friends with parent A in %s/007.php on line %d
diff --git a/Zend/tests/friends/008.phpt b/Zend/tests/friends/008.phpt
deleted file mode 100644
index 4dc79fc56cda1..0000000000000
--- a/Zend/tests/friends/008.phpt
+++ /dev/null
@@ -1,10 +0,0 @@
---TEST--
-No Friendship Interface
---FILE--
-<?php
-interface A for B {}
-
-class C implements A {}
-?>
---EXPECTF--
-Fatal error: Class C is not a friend of A in %s/008.php on line %d
diff --git a/Zend/tests/friends/010.phpt b/Zend/tests/friends/010.phpt
deleted file mode 100644
index 68fbf66be0597..0000000000000
--- a/Zend/tests/friends/010.phpt
+++ /dev/null
@@ -1,26 +0,0 @@
---TEST--
-Friendship Inheritance Interfaces
---FILE--
-<?php
-interface A for B,C {}
-
-interface B extends A {}
-
-foreach ([A::class, B::class] as $class) {
-    $reflector = new ReflectionClass($class);
-    
-    var_dump($reflector->getFriendNames());
-}
-?>
---EXPECT--
-array(2) {
-  [0]=>
-  string(1) "B"
-  [1]=>
-  string(1) "C"
-}
-array(1) {
-  [0]=>
-  string(1) "C"
-}
-
diff --git a/Zend/tests/sealed/001.phpt b/Zend/tests/sealed/001.phpt
new file mode 100644
index 0000000000000..4bfb0c59c48c6
--- /dev/null
+++ b/Zend/tests/sealed/001.phpt
@@ -0,0 +1,10 @@
+--TEST--
+Circular Sealing
+--FILE--
+<?php
+
+sealed class A permits A, B {}
+
+?>
+--EXPECTF--
+Fatal error: Sealed class A may not permit inheritance for itself in %s/001.php on line %d
diff --git a/Zend/tests/sealed/002.phpt b/Zend/tests/sealed/002.phpt
new file mode 100644
index 0000000000000..8636fed4dd007
--- /dev/null
+++ b/Zend/tests/sealed/002.phpt
@@ -0,0 +1,11 @@
+--TEST--
+Circular Sealing Parent
+--FILE--
+<?php
+
+sealed class A permits B {}
+
+sealed class B extends A permits A {}
+?>
+--EXPECTF--
+Fatal error: Sealed class B may not permit inheritance from its parent A in %s/002.php on line %d
diff --git a/Zend/tests/sealed/003.phpt b/Zend/tests/sealed/003.phpt
new file mode 100644
index 0000000000000..6b0630218b5ba
--- /dev/null
+++ b/Zend/tests/sealed/003.phpt
@@ -0,0 +1,13 @@
+--TEST--
+Not permitted class
+--FILE--
+<?php
+sealed class A permits B {}
+
+class B extends A {} // ok
+
+class C extends A {} // ko
+?>
+--EXPECTF--
+Fatal error: Class C is not permitted to inherit from A in %s/003.php on line %d
+
diff --git a/Zend/tests/sealed/004.phpt b/Zend/tests/sealed/004.phpt
new file mode 100644
index 0000000000000..a56fcdca6191a
--- /dev/null
+++ b/Zend/tests/sealed/004.phpt
@@ -0,0 +1,45 @@
+--TEST--
+Reflection
+--FILE--
+<?php
+sealed class A permits B {}
+class B extends A {}
+
+interface C permits D {}
+interface D extends C {}
+
+trait E permits F {}
+class F { use E; }
+
+foreach ([A::class, B::class, C::class, D::class, E::class, F::class] as $class) {
+    $reflector = new ReflectionClass($class);
+
+    var_dump($reflector->isSealed());
+    var_dump($reflector->getPermittedClasses());
+}
+?>
+--EXPECT--
+bool(true)
+array(1) {
+  [0]=>
+  string(1) "B"
+}
+bool(false)
+array(0) {
+}
+bool(true)
+array(1) {
+  [0]=>
+  string(1) "D"
+}
+bool(false)
+array(0) {
+}
+bool(true)
+array(1) {
+  [0]=>
+  string(1) "F"
+}
+bool(false)
+array(0) {
+}
diff --git a/Zend/tests/sealed/005.phpt b/Zend/tests/sealed/005.phpt
new file mode 100644
index 0000000000000..fb2ada7f65858
--- /dev/null
+++ b/Zend/tests/sealed/005.phpt
@@ -0,0 +1,39 @@
+--TEST--
+Sealing Inheritance
+--FILE--
+<?php
+sealed class A permits B, C {}
+
+sealed class B extends A permits C {}
+
+class C extends B {}
+
+class D {}
+
+foreach ([A::class, B::class, C::class, D::class] as $class) {
+    $reflector = new ReflectionClass($class);
+
+    var_dump($reflector->isSealed());
+    var_dump($reflector->getPermittedClasses());
+}
+?>
+--EXPECT--
+bool(true)
+array(2) {
+  [0]=>
+  string(1) "B"
+  [1]=>
+  string(1) "C"
+}
+bool(true)
+array(1) {
+  [0]=>
+  string(1) "C"
+}
+bool(false)
+array(0) {
+}
+bool(false)
+array(0) {
+}
+
diff --git a/Zend/tests/sealed/006.phpt b/Zend/tests/sealed/006.phpt
new file mode 100644
index 0000000000000..7640a317178d2
--- /dev/null
+++ b/Zend/tests/sealed/006.phpt
@@ -0,0 +1,8 @@
+--TEST--
+Circular Sealing Interface
+--FILE--
+<?php
+sealed interface A permits A, B {}
+?>
+--EXPECTF--
+Fatal error: Sealed interface A may not permit inheritance for itself in %s/001.php on line %d
diff --git a/Zend/tests/sealed/007.phpt b/Zend/tests/sealed/007.phpt
new file mode 100644
index 0000000000000..e84b7d4a3ce77
--- /dev/null
+++ b/Zend/tests/sealed/007.phpt
@@ -0,0 +1,10 @@
+--TEST--
+Circular Friendship Parent Interface
+--FILE--
+<?php
+sealed interface A permits B {}
+
+sealed interface B extends A permits A {}
+?>
+--EXPECTF--
+Fatal error: Sealed interface B may not permit inheritance from its parent A in %s/002.php on line %d
diff --git a/Zend/tests/sealed/008.phpt b/Zend/tests/sealed/008.phpt
new file mode 100644
index 0000000000000..6346ddf2f98c2
--- /dev/null
+++ b/Zend/tests/sealed/008.phpt
@@ -0,0 +1,10 @@
+--TEST--
+Not permitted class
+--FILE--
+<?php
+sealed interface A permits B {}
+
+final class C implements A {}
+?>
+--EXPECTF--
+Fatal error: Class C cannot implement sealed interface A in %s/008.php on line %d
diff --git a/Zend/tests/friends/009.phpt b/Zend/tests/sealed/009.phpt
similarity index 55%
rename from Zend/tests/friends/009.phpt
rename to Zend/tests/sealed/009.phpt
index a63dc1da956e4..e5c51e47af909 100644
--- a/Zend/tests/friends/009.phpt
+++ b/Zend/tests/sealed/009.phpt
@@ -1,21 +1,24 @@
 --TEST--
-Friendship Interfaces   
+Sealing Interfaces
 --FILE--
 <?php
-interface A for B {}
+sealed interface A permits B {}
 
 interface B extends A {}
 
 foreach ([A::class, B::class] as $class) {
     $reflector = new ReflectionClass($class);
-    
-    var_dump($reflector->getFriendNames());
+
+    var_dump($reflector->isSealed());
+    var_dump($reflector->getPermittedClasses());
 }
 ?>
 --EXPECT--
+bool(true)
 array(1) {
   [0]=>
   string(1) "B"
 }
+bool(false)
 array(0) {
 }
diff --git a/Zend/tests/sealed/010.phpt b/Zend/tests/sealed/010.phpt
new file mode 100644
index 0000000000000..8dcad5cb2d5ab
--- /dev/null
+++ b/Zend/tests/sealed/010.phpt
@@ -0,0 +1,38 @@
+--TEST--
+Sealing Inheritance Interfaces
+--FILE--
+<?php
+sealed interface A permits B, C {}
+
+interface B extends A {}
+
+sealed interface C extends A permits D {}
+
+interface D extends B, C {}
+
+foreach ([A::class, B::class, C::class, D::class] as $class) {
+    $reflector = new ReflectionClass($class);
+
+    var_dump($reflector->isSealed());
+    var_dump($reflector->getPermittedClasses());
+}
+?>
+--EXPECT--
+bool(true)
+array(2) {
+  [0]=>
+  string(1) "B"
+  [1]=>
+  string(1) "C"
+}
+bool(false)
+array(0) {
+}
+bool(true)
+array(1) {
+  [0]=>
+  string(1) "D"
+}
+bool(false)
+array(0) {
+}
diff --git a/Zend/tests/sealed/011.phpt b/Zend/tests/sealed/011.phpt
new file mode 100644
index 0000000000000..46ef1cf24776c
--- /dev/null
+++ b/Zend/tests/sealed/011.phpt
@@ -0,0 +1,36 @@
+--TEST--
+Happy path
+--FILE--
+<?php
+// ok - permits C, D
+sealed interface A permits C, D {}
+
+// ok, permitted to implements A
+class C implements A {}
+// ok, permitted to implements A
+class D implements A {}
+
+// ok, permitted to extend A implicitly
+interface E extends A {} // ok
+
+// ok, permitted to extend C ( non sealed ), permitted to implement E ( non sealed ) and parent interface is sealed to C
+// which we extend - permits G
+sealed class F extends C implements E permits G {}
+
+// ok, permitted to extend F
+class G extends F {}
+
+// ok - permits I
+sealed trait H permits I {}
+
+// ok, permitted to use H, permitted to extend G ( non sealed ) - permits J
+sealed abstract class I extends G permits J {
+ use H;
+}
+
+final class J extends I {} // ok, permitted to extend I
+?>
+OK
+--EXPECT--
+OK
+
diff --git a/Zend/tests/sealed/012.phpt b/Zend/tests/sealed/012.phpt
new file mode 100644
index 0000000000000..234a02bfc63b5
--- /dev/null
+++ b/Zend/tests/sealed/012.phpt
@@ -0,0 +1,24 @@
+--TEST--
+Implementing sealed interfaces
+--FILE--
+<?php
+sealed interface A permits C, D {}
+
+class C implements A {} // OK
+class D implements A {} // OK
+
+interface E extends A {} // OK
+
+interface F extends E {} // OK
+
+class G extends C implements E {} // OK
+class H extends D implements E {} // OK
+
+class I extends C implements F {} // OK
+class J extends D implements F {} // OK
+
+// F extends E - E extends A - A permits implementations only for C, and D
+class K implements F {} // K.O
+?>
+--EXPECT--
+Fatal error: Class K cannot implement sealed interface A in %s/012.php on line %d
diff --git a/Zend/tests/sealed/013.phpt b/Zend/tests/sealed/013.phpt
new file mode 100644
index 0000000000000..832ca5047392a
--- /dev/null
+++ b/Zend/tests/sealed/013.phpt
@@ -0,0 +1,32 @@
+--TEST--
+Using sealed traits
+--FILE--
+<?php
+sealed trait A permits C, D {
+  public function speak(): void
+  {
+    echo '*bark* ';
+  }
+}
+
+class C { use A; } // OK
+
+(new C)->speak();
+
+class D { use A; } // OK
+
+(new D)->speak();
+
+class G extends C {} // OK
+
+(new G)->speak();
+
+class H extends D {} // OK
+
+(new H)->speak();
+
+class K { use A; } // K.O
+?>
+--EXPECT--
+*bark* *bark* *bark* *bark*
+Fatal error: Class K cannot use sealed trait A in %s/013.php on line %d
diff --git a/Zend/zend_exceptions.c b/Zend/zend_exceptions.c
index 61a0aa923dda9..91c882a4e497c 100644
--- a/Zend/zend_exceptions.c
+++ b/Zend/zend_exceptions.c
@@ -50,6 +50,7 @@ ZEND_API void (*zend_throw_exception_hook)(zend_object *ex);
 
 static zend_object_handlers default_exception_handlers;
 
+/* @TODO: remove this check and declare Throwable sealed, permitting only Error and Exception */
 /* {{{ zend_implement_throwable */
 static int zend_implement_throwable(zend_class_entry *interface, zend_class_entry *class_type)
 {
diff --git a/ext/date/php_date.c b/ext/date/php_date.c
index 40f0ab6571c60..cd3cc7b3436a4 100644
--- a/ext/date/php_date.c
+++ b/ext/date/php_date.c
@@ -1556,6 +1556,7 @@ zend_object_iterator *date_object_period_get_iterator(zend_class_entry *ce, zval
 	return (zend_object_iterator*)iterator;
 } /* }}} */
 
+/* @TODO: remove this check and declare DateTimeInterface sealed, permitting only DateTime and DateTimeImmutable */
 static int implement_date_interface_handler(zend_class_entry *interface, zend_class_entry *implementor) /* {{{ */
 {
 	if (implementor->type == ZEND_USER_CLASS &&