diff --git a/NEWS b/NEWS
index 2bc7d6131aa81..476c00741d4a7 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,8 @@ PHP                                                                        NEWS
   . Fixed bug GH-16665 (\array and \callable should not be usable in
     class_alias). (nielsdos)
   . Added PHP_BUILD_DATE constant. (cmb)
+  . Added support for Closures in constant expressions. (timwolla,
+    Volker Dusch)
 
 - Curl:
   . Added curl_multi_get_handles(). (timwolla)
diff --git a/UPGRADING b/UPGRADING
index 9daf6cca22603..c319d7299a4c0 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -44,6 +44,10 @@ PHP 8.5 UPGRADE NOTES
 2. New Features
 ========================================
 
+- Core:
+  . Added support for Closures in constant expressions.
+    RFC: https://wiki.php.net/rfc/closures_in_const_expr
+
 - DOM:
   . Added Dom\Element::$outerHTML.
 
diff --git a/Zend/tests/closure_const_expr/attributes.phpt b/Zend/tests/closure_const_expr/attributes.phpt
new file mode 100644
index 0000000000000..c83b821d12969
--- /dev/null
+++ b/Zend/tests/closure_const_expr/attributes.phpt
@@ -0,0 +1,57 @@
+--TEST--
+Allow defining closures in attributes
+--EXTENSIONS--
+reflection
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class Attr {
+    public function __construct(public Closure $value) {
+      $value('foo');
+    }
+}
+
+#[Attr(static function () { })]
+#[Attr(static function (...$args) {
+  var_dump($args);
+})]
+class C {}
+
+foreach ((new ReflectionClass(C::class))->getAttributes() as $reflectionAttribute) {
+    var_dump($reflectionAttribute->newInstance());
+}
+
+?>
+--EXPECTF--
+object(Attr)#%d (1) {
+  ["value"]=>
+  object(Closure)#%d (3) {
+    ["name"]=>
+    string(%d) "{closure:%s:%d}"
+    ["file"]=>
+    string(%d) "%s"
+    ["line"]=>
+    int(%d)
+  }
+}
+array(1) {
+  [0]=>
+  string(3) "foo"
+}
+object(Attr)#%d (1) {
+  ["value"]=>
+  object(Closure)#%d (4) {
+    ["name"]=>
+    string(%d) "{closure:%s:%d}"
+    ["file"]=>
+    string(%d) "%s"
+    ["line"]=>
+    int(%d)
+    ["parameter"]=>
+    array(1) {
+      ["$args"]=>
+      string(10) "<optional>"
+    }
+  }
+}
diff --git a/Zend/tests/closure_const_expr/attributes_ast_printing.phpt b/Zend/tests/closure_const_expr/attributes_ast_printing.phpt
new file mode 100644
index 0000000000000..e87abf8c90611
--- /dev/null
+++ b/Zend/tests/closure_const_expr/attributes_ast_printing.phpt
@@ -0,0 +1,41 @@
+--TEST--
+AST printing for closures in attributes
+--FILE--
+<?php
+
+// Do not use `false &&` to fully evaluate the function / class definition.
+
+try {
+    \assert(
+        !
+        #[Attr(static function ($foo) {
+            echo $foo;
+        })]
+        function () { }
+    );
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    \assert(
+        !
+        new #[Attr(static function ($foo) {
+            echo $foo;
+        })]
+        class {}
+    );
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+assert(!#[Attr(static function ($foo) {
+    echo $foo;
+})] function () {
+})
+assert(!new #[Attr(static function ($foo) {
+    echo $foo;
+})] class {
+})
diff --git a/Zend/tests/closure_const_expr/attributes_scope_001.phpt b/Zend/tests/closure_const_expr/attributes_scope_001.phpt
new file mode 100644
index 0000000000000..6d89f410ca02b
--- /dev/null
+++ b/Zend/tests/closure_const_expr/attributes_scope_001.phpt
@@ -0,0 +1,28 @@
+--TEST--
+Closure in attribute may access private variables
+--EXTENSIONS--
+reflection
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class Attr {
+    public function __construct(public Closure $value) {}
+}
+
+#[Attr(static function (C $c) {
+    echo $c->secret, PHP_EOL;
+})]
+class C {
+    public function __construct(
+        private string $secret,
+    ) {}
+}
+
+foreach ((new ReflectionClass(C::class))->getAttributes() as $reflectionAttribute) {
+    ($reflectionAttribute->newInstance()->value)(new C('secret'));
+}
+
+?>
+--EXPECT--
+secret
diff --git a/Zend/tests/closure_const_expr/attributes_scope_002.phpt b/Zend/tests/closure_const_expr/attributes_scope_002.phpt
new file mode 100644
index 0000000000000..ac168fd02de46
--- /dev/null
+++ b/Zend/tests/closure_const_expr/attributes_scope_002.phpt
@@ -0,0 +1,35 @@
+--TEST--
+Closure in attribute may not access unrelated private variables
+--EXTENSIONS--
+reflection
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class Attr {
+    public function __construct(public Closure $value) {}
+}
+
+#[Attr(static function (E $e) {
+    echo $e->secret, PHP_EOL;
+})]
+class C {
+}
+
+class E {
+    public function __construct(
+        private string $secret,
+    ) {}
+}
+
+foreach ((new ReflectionClass(C::class))->getAttributes() as $reflectionAttribute) {
+    ($reflectionAttribute->newInstance()->value)(new E('secret'));
+}
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Cannot access private property E::$secret in %s:%d
+Stack trace:
+#0 %s(%d): C::{closure:%s:%d}(Object(E))
+#1 {main}
+  thrown in %s on line %d
diff --git a/Zend/tests/closure_const_expr/basic.phpt b/Zend/tests/closure_const_expr/basic.phpt
new file mode 100644
index 0000000000000..d1242c989b2d8
--- /dev/null
+++ b/Zend/tests/closure_const_expr/basic.phpt
@@ -0,0 +1,23 @@
+--TEST--
+Allow defining Closures in const expressions.
+--FILE--
+<?php
+
+const Closure = static function () {
+    echo "called", PHP_EOL;
+};
+
+var_dump(Closure);
+(Closure)();
+
+?>
+--EXPECTF--
+object(Closure)#%d (3) {
+  ["name"]=>
+  string(%d) "{closure:%s:%d}"
+  ["file"]=>
+  string(%d) "%s"
+  ["line"]=>
+  int(3)
+}
+called
diff --git a/Zend/tests/closure_const_expr/class_const.phpt b/Zend/tests/closure_const_expr/class_const.phpt
new file mode 100644
index 0000000000000..d392d0d7dfdc6
--- /dev/null
+++ b/Zend/tests/closure_const_expr/class_const.phpt
@@ -0,0 +1,25 @@
+--TEST--
+Allow defining Closures in class constants.
+--FILE--
+<?php
+
+class C {
+    const Closure = static function () {
+        echo "called", PHP_EOL;
+    };
+}
+
+var_dump(C::Closure);
+(C::Closure)();
+
+?>
+--EXPECTF--
+object(Closure)#%d (3) {
+  ["name"]=>
+  string(%d) "{closure:%s:%d}"
+  ["file"]=>
+  string(%d) "%s"
+  ["line"]=>
+  int(4)
+}
+called
diff --git a/Zend/tests/closure_const_expr/complex_array.phpt b/Zend/tests/closure_const_expr/complex_array.phpt
new file mode 100644
index 0000000000000..87044cb3659f5
--- /dev/null
+++ b/Zend/tests/closure_const_expr/complex_array.phpt
@@ -0,0 +1,41 @@
+--TEST--
+Allow defining Closures wrapped in an array in const expressions.
+--FILE--
+<?php
+
+const Closure = [static function () {
+    echo "called", PHP_EOL;
+}, static function () {
+    echo "also called", PHP_EOL;
+}];
+
+var_dump(Closure);
+
+foreach (Closure as $closure) {
+    $closure();
+}
+
+?>
+--EXPECTF--
+array(2) {
+  [0]=>
+  object(Closure)#%d (3) {
+    ["name"]=>
+    string(%d) "{closure:%s:%d}"
+    ["file"]=>
+    string(%d) "%s"
+    ["line"]=>
+    int(3)
+  }
+  [1]=>
+  object(Closure)#%d (3) {
+    ["name"]=>
+    string(%d) "{closure:%s:%d}"
+    ["file"]=>
+    string(%d) "%s"
+    ["line"]=>
+    int(5)
+  }
+}
+called
+also called
diff --git a/Zend/tests/closure_const_expr/complex_new.phpt b/Zend/tests/closure_const_expr/complex_new.phpt
new file mode 100644
index 0000000000000..9437bbdc259f4
--- /dev/null
+++ b/Zend/tests/closure_const_expr/complex_new.phpt
@@ -0,0 +1,33 @@
+--TEST--
+Allow defining Closures passed as constructor arguments in const expressions.
+--FILE--
+<?php
+
+class Dummy {
+  public function __construct(
+      public Closure $c,
+  ) {}
+}
+
+const Closure = new Dummy(static function () {
+  echo "called", PHP_EOL;
+});
+
+var_dump(Closure);
+
+(Closure->c)();
+
+?>
+--EXPECTF--
+object(Dummy)#%d (1) {
+  ["c"]=>
+  object(Closure)#%d (3) {
+    ["name"]=>
+    string(%d) "{closure:%s:%d}"
+    ["file"]=>
+    string(%d) "%s"
+    ["line"]=>
+    int(9)
+  }
+}
+called
diff --git a/Zend/tests/closure_const_expr/default_args.phpt b/Zend/tests/closure_const_expr/default_args.phpt
new file mode 100644
index 0000000000000..f1a9ee48f1146
--- /dev/null
+++ b/Zend/tests/closure_const_expr/default_args.phpt
@@ -0,0 +1,22 @@
+--TEST--
+Closures in default argument
+--FILE--
+<?php
+
+function test(
+    Closure $name = static function () {
+        echo "default", PHP_EOL;
+    },
+) {
+    $name();
+}
+
+test();
+test(function () {
+    echo "explicit", PHP_EOL;
+});
+
+?>
+--EXPECT--
+default
+explicit
diff --git a/Zend/tests/closure_const_expr/disallows_non_static.phpt b/Zend/tests/closure_const_expr/disallows_non_static.phpt
new file mode 100644
index 0000000000000..3e67a0a4829f8
--- /dev/null
+++ b/Zend/tests/closure_const_expr/disallows_non_static.phpt
@@ -0,0 +1,18 @@
+--TEST--
+Disallows using non-static closures.
+--FILE--
+<?php
+
+class C {
+    public Closure $d = function () {
+        var_dump($this);
+    };
+}
+
+$foo = new C();
+var_dump($foo->d);
+($foo->d)();
+
+?>
+--EXPECTF--
+Fatal error: Closures in constant expressions must be static in %s on line %d
diff --git a/Zend/tests/closure_const_expr/disallows_using_variables.phpt b/Zend/tests/closure_const_expr/disallows_using_variables.phpt
new file mode 100644
index 0000000000000..a7a212decf332
--- /dev/null
+++ b/Zend/tests/closure_const_expr/disallows_using_variables.phpt
@@ -0,0 +1,17 @@
+--TEST--
+Disallows using variables.
+--FILE--
+<?php
+
+$foo = "bar";
+
+const Closure = static function () use ($foo) {
+    echo $foo, PHP_EOL;
+};
+
+var_dump(Closure);
+(Closure)();
+
+?>
+--EXPECTF--
+Fatal error: Cannot use(...) variables in constant expression in %s on line %d
diff --git a/Zend/tests/closure_const_expr/property_initializer.phpt b/Zend/tests/closure_const_expr/property_initializer.phpt
new file mode 100644
index 0000000000000..077a4e4f79a11
--- /dev/null
+++ b/Zend/tests/closure_const_expr/property_initializer.phpt
@@ -0,0 +1,27 @@
+--TEST--
+Closure in property initializer
+--FILE--
+<?php
+
+class C {
+    public Closure $d = static function () {
+        echo "called", PHP_EOL;
+    };
+}
+
+$c = new C();
+var_dump($c->d);
+($c->d)();
+
+
+?>
+--EXPECTF--
+object(Closure)#%d (3) {
+  ["name"]=>
+  string(%d) "{closure:%s:%d}"
+  ["file"]=>
+  string(%d) "%s"
+  ["line"]=>
+  int(4)
+}
+called
diff --git a/Zend/tests/closure_const_expr/property_initializer_scope_001.phpt b/Zend/tests/closure_const_expr/property_initializer_scope_001.phpt
new file mode 100644
index 0000000000000..bbd5b5b0ad84c
--- /dev/null
+++ b/Zend/tests/closure_const_expr/property_initializer_scope_001.phpt
@@ -0,0 +1,22 @@
+--TEST--
+Closure in property initializer may access private variables
+--FILE--
+<?php
+
+class C {
+    public Closure $d = static function (C $c) {
+        echo $c->secret, PHP_EOL;
+    };
+
+    public function __construct(
+        private string $secret,
+    ) {}
+}
+
+$c = new C('secret');
+($c->d)($c);
+
+
+?>
+--EXPECTF--
+secret
diff --git a/Zend/tests/closure_const_expr/property_initializer_scope_002.phpt b/Zend/tests/closure_const_expr/property_initializer_scope_002.phpt
new file mode 100644
index 0000000000000..a1c6942da1765
--- /dev/null
+++ b/Zend/tests/closure_const_expr/property_initializer_scope_002.phpt
@@ -0,0 +1,30 @@
+--TEST--
+Closure in property initializer may not access unrelated private variables
+--FILE--
+<?php
+
+class C {
+    public Closure $d = static function (E $e) {
+        echo $e->secret, PHP_EOL;
+    };
+
+    
+}
+
+class E {
+    public function __construct(
+        private string $secret,
+    ) {}
+}
+
+$c = new C();
+($c->d)(new E('secret'));
+
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Cannot access private property E::$secret in %s:%d
+Stack trace:
+#0 %s(%d): C::{closure:%s:%d}(Object(E))
+#1 {main}
+  thrown in %s on line %d
diff --git a/Zend/tests/closure_const_expr/static_initalizer.phpt b/Zend/tests/closure_const_expr/static_initalizer.phpt
new file mode 100644
index 0000000000000..65bfb37393d42
--- /dev/null
+++ b/Zend/tests/closure_const_expr/static_initalizer.phpt
@@ -0,0 +1,27 @@
+--TEST--
+Closure in static initializer
+--FILE--
+<?php
+
+function foo() {
+    static $closure = static function () {
+        echo "called", PHP_EOL;
+    };
+
+    var_dump($closure);
+    $closure();
+}
+
+foo();
+
+?>
+--EXPECTF--
+object(Closure)#%d (3) {
+  ["name"]=>
+  string(17) "{closure:foo():4}"
+  ["file"]=>
+  string(%d) "%s"
+  ["line"]=>
+  int(4)
+}
+called
diff --git a/Zend/tests/closure_const_expr/static_property_initializer.phpt b/Zend/tests/closure_const_expr/static_property_initializer.phpt
new file mode 100644
index 0000000000000..0b7249d78bd6f
--- /dev/null
+++ b/Zend/tests/closure_const_expr/static_property_initializer.phpt
@@ -0,0 +1,26 @@
+--TEST--
+Closure in static property initializer
+--FILE--
+<?php
+
+class C {
+    public static Closure $d = static function () {
+        echo "called", PHP_EOL;
+    };
+}
+
+var_dump(C::$d);
+(C::$d)();
+
+
+?>
+--EXPECTF--
+object(Closure)#%d (3) {
+  ["name"]=>
+  string(%d) "{closure:%s:%d}"
+  ["file"]=>
+  string(%d) "%s"
+  ["line"]=>
+  int(4)
+}
+called
diff --git a/Zend/zend_ast.c b/Zend/zend_ast.c
index d33747412ef0a..74dd471fb2cba 100644
--- a/Zend/zend_ast.c
+++ b/Zend/zend_ast.c
@@ -23,6 +23,7 @@
 #include "zend_language_parser.h"
 #include "zend_smart_str.h"
 #include "zend_exceptions.h"
+#include "zend_closures.h"
 #include "zend_constants.h"
 #include "zend_enum.h"
 
@@ -989,6 +990,13 @@ ZEND_API zend_result ZEND_FASTCALL zend_ast_evaluate_inner(
 			}
 			return SUCCESS;
 		}
+		case ZEND_AST_OP_ARRAY:
+		{
+			zend_function *func = Z_PTR_P(&((zend_ast_zval*)(ast))->val);
+
+			zend_create_closure(result, func, scope, scope, NULL);
+			return SUCCESS;
+		}
 		case ZEND_AST_PROP:
 		case ZEND_AST_NULLSAFE_PROP:
 		{
@@ -1068,7 +1076,7 @@ static size_t ZEND_FASTCALL zend_ast_tree_size(zend_ast *ast)
 {
 	size_t size;
 
-	if (ast->kind == ZEND_AST_ZVAL || ast->kind == ZEND_AST_CONSTANT) {
+	if (ast->kind == ZEND_AST_ZVAL || ast->kind == ZEND_AST_CONSTANT || ast->kind == ZEND_AST_OP_ARRAY) {
 		size = sizeof(zend_ast_zval);
 	} else if (zend_ast_is_list(ast)) {
 		uint32_t i;
@@ -1126,6 +1134,13 @@ static void* ZEND_FASTCALL zend_ast_tree_copy(zend_ast *ast, void *buf)
 				new->child[i] = NULL;
 			}
 		}
+	} else if (ast->kind == ZEND_AST_OP_ARRAY) {
+		zend_ast_zval *new = (zend_ast_zval*)buf;
+		new->kind = ZEND_AST_OP_ARRAY;
+		new->attr = ast->attr;
+		ZVAL_COPY(&new->val, &((zend_ast_zval *) ast)->val);
+		Z_LINENO(new->val) = zend_ast_get_lineno(ast);
+		buf = (void*)((char*)buf + sizeof(zend_ast_zval));
 	} else {
 		uint32_t i, children = zend_ast_get_num_children(ast);
 		zend_ast *new = (zend_ast*)buf;
@@ -1189,6 +1204,8 @@ ZEND_API void ZEND_FASTCALL zend_ast_destroy(zend_ast *ast)
 		}
 	} else if (EXPECTED(ast->kind == ZEND_AST_CONSTANT)) {
 		zend_string_release_ex(zend_ast_get_constant_name(ast), 0);
+	} else if (EXPECTED(ast->kind == ZEND_AST_OP_ARRAY)) {
+		ZEND_ASSERT(!Z_REFCOUNTED(((zend_ast_zval*)(ast))->val));
 	} else if (EXPECTED(ast->kind >= ZEND_AST_FUNC_DECL)) {
 		zend_ast_decl *decl = (zend_ast_decl *) ast;
 
diff --git a/Zend/zend_ast.h b/Zend/zend_ast.h
index 8d1d93f2564a7..6f68a961b7989 100644
--- a/Zend/zend_ast.h
+++ b/Zend/zend_ast.h
@@ -35,6 +35,7 @@ enum _zend_ast_kind {
 	/* special nodes */
 	ZEND_AST_ZVAL = 1 << ZEND_AST_SPECIAL_SHIFT,
 	ZEND_AST_CONSTANT,
+	ZEND_AST_OP_ARRAY,
 	ZEND_AST_ZNODE,
 
 	/* declaration nodes */
@@ -362,7 +363,7 @@ static zend_always_inline uint32_t zend_ast_get_lineno(zend_ast *ast) {
 	if (ast->kind == ZEND_AST_ZVAL) {
 		zval *zv = zend_ast_get_zval(ast);
 		return Z_LINENO_P(zv);
-	} else if (ast->kind == ZEND_AST_CONSTANT) {
+	} else if (ast->kind == ZEND_AST_CONSTANT || ast->kind == ZEND_AST_OP_ARRAY) {
 		zval *zv = &((zend_ast_zval *) ast)->val;
 		return Z_LINENO_P(zv);
 	} else {
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 7e5351ddfafdb..c307a823898a1 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -8138,7 +8138,13 @@ static uint32_t zend_add_dynamic_func_def(zend_op_array *def) {
 	return def_offset;
 }
 
-static zend_string *zend_begin_func_decl(znode *result, zend_op_array *op_array, zend_ast_decl *decl, bool toplevel) /* {{{ */
+enum func_decl_level {
+	FUNC_DECL_LEVEL_TOPLEVEL,
+	FUNC_DECL_LEVEL_NESTED,
+	FUNC_DECL_LEVEL_CONSTEXPR,
+};
+
+static zend_string *zend_begin_func_decl(znode *result, zend_op_array *op_array, zend_ast_decl *decl, enum func_decl_level level) /* {{{ */
 {
 	zend_string *unqualified_name, *name, *lcname;
 	zend_op *opline;
@@ -8208,25 +8214,34 @@ static zend_string *zend_begin_func_decl(znode *result, zend_op_array *op_array,
 	}
 
 	zend_register_seen_symbol(lcname, ZEND_SYMBOL_FUNCTION);
-	if (!toplevel) {
-		uint32_t func_ref = zend_add_dynamic_func_def(op_array);
-		if (op_array->fn_flags & ZEND_ACC_CLOSURE) {
-			opline = zend_emit_op_tmp(result, ZEND_DECLARE_LAMBDA_FUNCTION, NULL, NULL);
-			opline->op2.num = func_ref;
-		} else {
-			opline = get_next_op();
-			opline->opcode = ZEND_DECLARE_FUNCTION;
-			opline->op1_type = IS_CONST;
-			LITERAL_STR(opline->op1, zend_string_copy(lcname));
-			opline->op2.num = func_ref;
+	switch (level) {
+		case FUNC_DECL_LEVEL_CONSTEXPR:
+			zend_add_dynamic_func_def(op_array);
+			break;
+		case FUNC_DECL_LEVEL_NESTED: {
+			uint32_t func_ref = zend_add_dynamic_func_def(op_array);
+			if (op_array->fn_flags & ZEND_ACC_CLOSURE) {
+				opline = zend_emit_op_tmp(result, ZEND_DECLARE_LAMBDA_FUNCTION, NULL, NULL);
+				opline->op2.num = func_ref;
+			} else {
+				opline = get_next_op();
+				opline->opcode = ZEND_DECLARE_FUNCTION;
+				opline->op1_type = IS_CONST;
+				LITERAL_STR(opline->op1, zend_string_copy(lcname));
+				opline->op2.num = func_ref;
+			}
+			break;
 		}
+		case FUNC_DECL_LEVEL_TOPLEVEL:
+			/* Nothing to do. */
+			break;
 	}
 	return lcname;
 }
 /* }}} */
 
 static zend_op_array *zend_compile_func_decl_ex(
-	znode *result, zend_ast *ast, bool toplevel,
+	znode *result, zend_ast *ast, enum func_decl_level level,
 	const zend_property_info *property_info,
 	zend_property_hook_kind hook_kind
 ) {
@@ -8272,7 +8287,7 @@ static zend_op_array *zend_compile_func_decl_ex(
 		bool has_body = stmt_ast != NULL;
 		lcname = zend_begin_method_decl(op_array, decl->name, has_body);
 	} else {
-		lcname = zend_begin_func_decl(result, op_array, decl, toplevel);
+		lcname = zend_begin_func_decl(result, op_array, decl, level);
 		if (decl->kind == ZEND_AST_ARROW_FUNC) {
 			find_implicit_binds(&info, params_ast, stmt_ast);
 			compile_implicit_lexical_binds(&info, result, op_array);
@@ -8320,7 +8335,7 @@ static zend_op_array *zend_compile_func_decl_ex(
 		CG(active_class_entry) = NULL;
 	}
 
-	if (toplevel) {
+	if (level == FUNC_DECL_LEVEL_TOPLEVEL) {
 		op_array->fn_flags |= ZEND_ACC_TOP_LEVEL;
 	}
 
@@ -8367,7 +8382,7 @@ static zend_op_array *zend_compile_func_decl_ex(
 		CG(zend_lineno) = decl->start_lineno;
 		zend_check_magic_method_implementation(
 			CG(active_class_entry), (zend_function *) op_array, lcname, E_COMPILE_ERROR);
-	} else if (toplevel) {
+	} else if (level == FUNC_DECL_LEVEL_TOPLEVEL) {
 		/* Only register the function after a successful compile */
 		if (UNEXPECTED(zend_hash_add_ptr(CG(function_table), lcname, op_array) == NULL)) {
 			CG(zend_lineno) = decl->start_lineno;
@@ -8387,7 +8402,7 @@ static zend_op_array *zend_compile_func_decl_ex(
 	/* Pop the loop variable stack separator */
 	zend_stack_del_top(&CG(loop_var_stack));
 
-	if (toplevel) {
+	if (level == FUNC_DECL_LEVEL_TOPLEVEL) {
 		zend_observer_function_declared_notify(op_array, lcname);
 	}
 
@@ -8401,9 +8416,9 @@ static zend_op_array *zend_compile_func_decl_ex(
 	return op_array;
 }
 
-static zend_op_array *zend_compile_func_decl(znode *result, zend_ast *ast, bool toplevel)
+static zend_op_array *zend_compile_func_decl(znode *result, zend_ast *ast, enum func_decl_level level)
 {
-	return zend_compile_func_decl_ex(result, ast, toplevel, /* property_info */ NULL, (zend_property_hook_kind)-1);
+	return zend_compile_func_decl_ex(result, ast, level, /* property_info */ NULL, (zend_property_hook_kind)-1);
 }
 
 zend_property_hook_kind zend_get_property_hook_kind_from_name(zend_string *name) {
@@ -8542,7 +8557,7 @@ static void zend_compile_property_hooks(
 		hook->name = zend_strpprintf(0, "$%s::%s", ZSTR_VAL(prop_name), ZSTR_VAL(name));
 
 		zend_function *func = (zend_function *) zend_compile_func_decl_ex(
-			NULL, (zend_ast *) hook, /* toplevel */ false, prop_info, hook_kind);
+			NULL, (zend_ast *) hook, FUNC_DECL_LEVEL_NESTED, prop_info, hook_kind);
 
 		func->common.prop_info = prop_info;
 
@@ -11049,7 +11064,8 @@ static bool zend_is_allowed_in_const_expr(zend_ast_kind kind) /* {{{ */
 		|| kind == ZEND_AST_CONST_ENUM_INIT
 		|| kind == ZEND_AST_NEW || kind == ZEND_AST_ARG_LIST
 		|| kind == ZEND_AST_NAMED_ARG
-		|| kind == ZEND_AST_PROP || kind == ZEND_AST_NULLSAFE_PROP;
+		|| kind == ZEND_AST_PROP || kind == ZEND_AST_NULLSAFE_PROP
+		|| kind == ZEND_AST_CLOSURE;
 }
 /* }}} */
 
@@ -11183,6 +11199,29 @@ static void zend_compile_const_expr_new(zend_ast **ast_ptr)
 	class_ast->attr = fetch_type << ZEND_CONST_EXPR_NEW_FETCH_TYPE_SHIFT;
 }
 
+static void zend_compile_const_expr_closure(zend_ast **ast_ptr)
+{
+	zend_ast_decl *closure_ast = (zend_ast_decl *) *ast_ptr;
+	zend_ast *uses_ast = closure_ast->child[1];
+	if (!(closure_ast->flags & ZEND_ACC_STATIC)) {
+		zend_error_noreturn(E_COMPILE_ERROR,
+			"Closures in constant expressions must be static");
+	}
+	if (uses_ast) {
+		zend_error_noreturn(E_COMPILE_ERROR,
+			"Cannot use(...) variables in constant expression");
+	}
+
+	znode node;
+	zend_op_array *op = zend_compile_func_decl(&node, *ast_ptr, FUNC_DECL_LEVEL_CONSTEXPR);
+
+	zend_ast_destroy(*ast_ptr);
+	zval z;
+	ZVAL_PTR(&z, op);
+	*ast_ptr = zend_ast_create_zval(&z);
+	(*ast_ptr)->kind = ZEND_AST_OP_ARRAY;
+}
+
 static void zend_compile_const_expr_args(zend_ast **ast_ptr)
 {
 	zend_ast_list *list = zend_ast_get_list(*ast_ptr);
@@ -11245,6 +11284,9 @@ static void zend_compile_const_expr(zend_ast **ast_ptr, void *context) /* {{{ */
 		case ZEND_AST_ARG_LIST:
 			zend_compile_const_expr_args(ast_ptr);
 			break;
+		case ZEND_AST_CLOSURE:
+			zend_compile_const_expr_closure(ast_ptr);
+			break;
 	}
 
 	zend_ast_apply(ast, zend_compile_const_expr, context);
@@ -11287,7 +11329,7 @@ void zend_compile_top_stmt(zend_ast *ast) /* {{{ */
 
 	if (ast->kind == ZEND_AST_FUNC_DECL) {
 		CG(zend_lineno) = ast->lineno;
-		zend_compile_func_decl(NULL, ast, 1);
+		zend_compile_func_decl(NULL, ast, FUNC_DECL_LEVEL_TOPLEVEL);
 		CG(zend_lineno) = ((zend_ast_decl *) ast)->end_lineno;
 	} else if (ast->kind == ZEND_AST_CLASS) {
 		CG(zend_lineno) = ast->lineno;
@@ -11369,7 +11411,7 @@ static void zend_compile_stmt(zend_ast *ast) /* {{{ */
 			break;
 		case ZEND_AST_FUNC_DECL:
 		case ZEND_AST_METHOD:
-			zend_compile_func_decl(NULL, ast, 0);
+			zend_compile_func_decl(NULL, ast, FUNC_DECL_LEVEL_NESTED);
 			break;
 		case ZEND_AST_ENUM_CASE:
 			zend_compile_enum_case(ast);
@@ -11546,7 +11588,7 @@ static void zend_compile_expr_inner(znode *result, zend_ast *ast) /* {{{ */
 			return;
 		case ZEND_AST_CLOSURE:
 		case ZEND_AST_ARROW_FUNC:
-			zend_compile_func_decl(result, ast, 0);
+			zend_compile_func_decl(result, ast, FUNC_DECL_LEVEL_NESTED);
 			return;
 		case ZEND_AST_THROW:
 			zend_compile_throw(result, ast);
diff --git a/ext/opcache/zend_file_cache.c b/ext/opcache/zend_file_cache.c
index fe54c477cea77..f12170e8c9936 100644
--- a/ext/opcache/zend_file_cache.c
+++ b/ext/opcache/zend_file_cache.c
@@ -363,6 +363,9 @@ static void zend_file_cache_serialize_ast(zend_ast                 *ast,
 				zend_file_cache_serialize_ast(tmp, script, info, buf);
 			}
 		}
+	} else if (ast->kind == ZEND_AST_OP_ARRAY) {
+		/* The op_array itself will be serialized as part of the dynamic_func_defs. */
+		SERIALIZE_PTR(Z_PTR(((zend_ast_zval*)ast)->val));
 	} else {
 		uint32_t children = zend_ast_get_num_children(ast);
 		for (i = 0; i < children; i++) {
@@ -1242,6 +1245,9 @@ static void zend_file_cache_unserialize_ast(zend_ast                *ast,
 				zend_file_cache_unserialize_ast(list->child[i], script, buf);
 			}
 		}
+	} else if (ast->kind == ZEND_AST_OP_ARRAY) {
+		/* The op_array itself will be unserialized as part of the dynamic_func_defs. */
+		UNSERIALIZE_PTR(Z_PTR(((zend_ast_zval*)ast)->val));
 	} else {
 		uint32_t children = zend_ast_get_num_children(ast);
 		for (i = 0; i < children; i++) {
diff --git a/ext/opcache/zend_persist.c b/ext/opcache/zend_persist.c
index c5ddc040b22d8..11babd8aa4067 100644
--- a/ext/opcache/zend_persist.c
+++ b/ext/opcache/zend_persist.c
@@ -188,6 +188,10 @@ static zend_ast *zend_persist_ast(zend_ast *ast)
 			}
 		}
 		node = (zend_ast *) copy;
+	} else if (ast->kind == ZEND_AST_OP_ARRAY) {
+		zend_ast_zval *copy = zend_shared_memdup(ast, sizeof(zend_ast_zval));
+		zend_persist_op_array(&copy->val);
+		node = (zend_ast *) copy;
 	} else {
 		uint32_t children = zend_ast_get_num_children(ast);
 		node = zend_shared_memdup(ast, zend_ast_size(children));
diff --git a/ext/opcache/zend_persist_calc.c b/ext/opcache/zend_persist_calc.c
index d7a0455e3e5c1..fe58d3f2de277 100644
--- a/ext/opcache/zend_persist_calc.c
+++ b/ext/opcache/zend_persist_calc.c
@@ -86,6 +86,9 @@ static void zend_persist_ast_calc(zend_ast *ast)
 				zend_persist_ast_calc(list->child[i]);
 			}
 		}
+	} else if (ast->kind == ZEND_AST_OP_ARRAY) {
+		ADD_SIZE(sizeof(zend_ast_zval));
+		zend_persist_op_array_calc(&((zend_ast_zval*)(ast))->val);
 	} else {
 		uint32_t children = zend_ast_get_num_children(ast);
 		ADD_SIZE(zend_ast_size(children));