Implement enums

UPGRADING

@@ -119,6 +119,8 @@ PHP 8.1 UPGRADE NOTES
     RFC: https://wiki.php.net/rfc/explicit_octal_notation
   . Added support for array unpacking with strings keys.
     RFC: https://wiki.php.net/rfc/array_unpacking_string_keys
+  . Added support for enumerations.
+    RFC: https://wiki.php.net/rfc/enumerations
 
 - Curl:
   . Added CURLOPT_DOH_URL option.

Zend/Optimizer/zend_inference.c

@@ -3486,7 +3486,7 @@ static zend_always_inline int _zend_update_type_info(
 			break;
 		case ZEND_FETCH_CONSTANT:
 		case ZEND_FETCH_CLASS_CONSTANT:
-			UPDATE_SSA_TYPE(MAY_BE_RC1|MAY_BE_RCN|MAY_BE_NULL|MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_LONG|MAY_BE_DOUBLE|MAY_BE_STRING|MAY_BE_RESOURCE|MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY, ssa_op->result_def);
+			UPDATE_SSA_TYPE(MAY_BE_RC1|MAY_BE_RCN|MAY_BE_ANY|MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY, ssa_op->result_def);
 			break;
 		case ZEND_STRLEN:
 			tmp = MAY_BE_LONG;

Zend/tests/enum/__call.phpt

@@ -0,0 +1,29 @@
+--TEST--
+Enum __call
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function __call(string $name, array $args)
+    {
+        return [$name, $args];
+    }
+}
+
+var_dump(Foo::Bar->baz('qux', 'quux'));
+
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(3) "baz"
+  [1]=>
+  array(2) {
+    [0]=>
+    string(3) "qux"
+    [1]=>
+    string(4) "quux"
+  }
+}

Zend/tests/enum/__callStatic.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Enum __callStatic
+--FILE--
+<?php
+
+enum Foo {
+    public static function __callStatic(string $name, array $args)
+    {
+        return [$name, $args];
+    }
+}
+
+var_dump(Foo::bar('baz', 'qux'));
+
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(3) "bar"
+  [1]=>
+  array(2) {
+    [0]=>
+    string(3) "baz"
+    [1]=>
+    string(3) "qux"
+  }
+}

Zend/tests/enum/__class__.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Enum __CLASS__
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function printClass()
+    {
+        echo __CLASS__ . "\n";
+    }
+}
+
+Foo::Bar->printClass();
+
+?>
+--EXPECT--
+Foo

Zend/tests/enum/__function__.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Enum __FUNCTION__
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function printFunction()
+    {
+        echo __FUNCTION__ . "\n";
+    }
+}
+
+Foo::Bar->printFunction();
+
+?>
+--EXPECT--
+printFunction

Zend/tests/enum/__get.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Enum __get
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function __get(string $name)
+    {
+        return '__get';
+    }
+}
+
+?>
+--EXPECTF--
+Fatal error: Enum may not include __get in %s on line %d

Zend/tests/enum/__invoke.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Enum __invoke
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function __invoke(...$args)
+    {
+        return $args;
+    }
+}
+
+var_dump((Foo::Bar)('baz', 'qux'));
+
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(3) "baz"
+  [1]=>
+  string(3) "qux"
+}

Zend/tests/enum/__isset.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Enum __isset
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function __isset($property) {
+        return true;
+    }
+}
+
+?>
+--EXPECTF--
+Fatal error: Enum may not include __isset in %s on line %d

Zend/tests/enum/__method__.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Enum __METHOD__
+--FILE--
+<?php
+
+enum Foo {
+    case Bar;
+
+    public function printMethod()
+    {
+        echo __METHOD__ . "\n";
+    }
+}
+
+Foo::Bar->printMethod();
+
+?>
+--EXPECT--
+Foo::printMethod

Zend/tests/enum/ast-dumper.phpt

@@ -0,0 +1,48 @@
+--TEST--
+Enum AST dumper
+--FILE--
+<?php
+
+try {
+    assert((function () {
+        enum Foo {
+            case Bar;
+        }
+
+        #[EnumAttr]
+        enum IntFoo: int {
+            #[CaseAttr]
+            case Bar = 1 << 0;
+            case Baz = 1 << 1;
+
+            public function self() {
+                return $this;
+            }
+        }
+
+        return false;
+    })());
+} catch (Error $e) {
+    echo $e->getMessage();
+}
+
+?>
+--EXPECT--
+assert(function () {
+    enum Foo {
+        case Bar;
+    }
+
+    #[EnumAttr]
+    enum IntFoo: int {
+        #[CaseAttr]
+        case Bar = 1 << 0;
+        case Baz = 1 << 1;
+        public function self() {
+            return $this;
+        }
+
+    }
+
+    return false;
+}())

Zend/tests/enum/backed-cases-int.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Int backed enums with can list cases
+--FILE--
+<?php
+
+enum Suit: int {
+    case Hearts = 2;
+    case Diamonds = 1;
+    case Clubs = 4;
+    case Spades = 3;
+}
+
+var_dump(Suit::cases());
+
+?>
+--EXPECT--
+array(4) {
+  [0]=>
+  enum(Suit::Hearts)
+  [1]=>
+  enum(Suit::Diamonds)
+  [2]=>
+  enum(Suit::Clubs)
+  [3]=>
+  enum(Suit::Spades)
+}

Zend/tests/enum/backed-cases-string.phpt

@@ -0,0 +1,26 @@
+--TEST--
+String backed enums can list cases
+--FILE--
+<?php
+
+enum Suit: string {
+    case Hearts = 'H';
+    case Diamonds = 'D';
+    case Clubs = 'C';
+    case Spades = 'S';
+}
+
+var_dump(Suit::cases());
+
+?>
+--EXPECT--
+array(4) {
+  [0]=>
+  enum(Suit::Hearts)
+  [1]=>
+  enum(Suit::Diamonds)
+  [2]=>
+  enum(Suit::Clubs)
+  [3]=>
+  enum(Suit::Spades)
+}

Zend/tests/enum/backed-duplicate-int.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Backed enums reject duplicate int values
+--FILE--
+<?php
+
+enum Foo: int {
+    case Bar = 0;
+    case Baz = 0;
+}
+
+?>
+--EXPECTF--
+Fatal error: Duplicate value in enum Foo for cases Bar and Baz in %s on line %s

Zend/tests/enum/backed-duplicate-string.phpt

@@ -0,0 +1,15 @@
+--TEST--
+Backed enums reject duplicate string values
+--FILE--
+<?php
+
+enum Suit: string {
+    case Hearts = 'H';
+    case Diamonds = 'D';
+    case Clubs = 'C';
+    case Spades = 'H';
+}
+
+?>
+--EXPECTF--
+Fatal error: Duplicate value in enum Suit for cases Hearts and Spades in %s on line %s

Zend/tests/enum/backed-from-invalid-int.phpt

@@ -0,0 +1,19 @@
+--TEST--
+BackedEnum::from() reject invalid int
+--FILE--
+<?php
+
+enum Foo: int {
+    case Bar = 0;
+    case Baz = 1;
+}
+
+try {
+    var_dump(Foo::from(2));
+} catch (Error $e) {
+    echo $e->getMessage() . "\n";
+}
+
+?>
+--EXPECT--
+2 is not a valid backing value for enum "Foo"

Zend/tests/enum/backed-from-invalid-string.phpt

@@ -0,0 +1,21 @@
+--TEST--
+BackedEnum::from() reject invalid string
+--FILE--
+<?php
+
+enum Suit: string {
+    case Hearts = 'H';
+    case Diamonds = 'D';
+    case Clubs = 'C';
+    case Spades = 'S';
+}
+
+try {
+    var_dump(Suit::from('A'));
+} catch (Error $e) {
+    echo $e->getMessage() . "\n";
+}
+
+?>
+--EXPECT--
+"A" is not a valid backing value for enum "Suit"