[RFC] Add support for attributes on compile-time constants

https://wiki.php.net/rfc/attributes-on-constants

Author: DanielEScherzer

UPGRADING

@@ -133,6 +133,10 @@ PHP 8.5 UPGRADE NOTES
   . Added asymmetric visibility support for static properties.
     RFC: https://wiki.php.net/rfc/static-aviz
   . Added support for casts in constant expressions.
+  . Added support for attributes on compile-time non-class constants.
+    RFC: https://wiki.php.net/rfc/attributes-on-constants
+  . The #[\Deprecated] attribute can now be used on constants.
+    RFC: https://wiki.php.net/rfc/attributes-on-constants
 
 - Curl:
   . Added support for share handles that are persisted across multiple PHP
@@ -337,6 +341,8 @@ PHP 8.5 UPGRADE NOTES
   . ReflectionConstant::getFileName() was introduced.
   . ReflectionConstant::getExtension() and
     ReflectionConstant::getExtensionName() were introduced.
+  . ReflectionConstant::getAttributes() was introduced.
+    RFC: https://wiki.php.net/rfc/attributes-on-constants
 
 ========================================
 7. New Classes and Interfaces

Zend/tests/attributes/001_placement.phpt

@@ -25,6 +25,9 @@ $f2 = #[A1(9)] function () { };
 
 $f3 = #[A1(10)] fn () => 1;
 
+#[A1(11)]
+const CT_CONSTANT = 'Demo';
+
 $ref = new \ReflectionClass(Foo::class);
 
 $sources = [
@@ -37,7 +40,8 @@ $sources = [
     new \ReflectionObject($object),
     new \ReflectionFunction('f1'),
     new \ReflectionFunction($f2),
-    new \ReflectionFunction($f3)
+    new \ReflectionFunction($f3),
+    new \ReflectionConstant('CT_CONSTANT'),
 ];
 
 foreach ($sources as $r) {
@@ -132,3 +136,11 @@ array(1) {
   [0]=>
   int(10)
 }
+
+string(18) "ReflectionConstant"
+int(1)
+string(2) "A1"
+array(1) {
+  [0]=>
+  int(11)
+}

Zend/tests/attributes/029_reflect_internal_symbols.phpt

@@ -18,6 +18,9 @@ var_dump($rcc->getAttributes());
 $rp = new ReflectionProperty('Exception', 'message');
 var_dump($rp->getAttributes());
 
+$rct = new ReflectionConstant('PHP_VERSION');
+var_dump($rct->getAttributes());
+
 ?>
 --EXPECT--
 array(0) {
@@ -30,3 +33,5 @@ array(0) {
 }
 array(0) {
 }
+array(0) {
+}

Zend/tests/attributes/034_target_values.phpt

@@ -0,0 +1,39 @@
+--TEST--
+Attribute flags are all different, TARGET_ALL includes all targets
+--FILE--
+<?php
+
+function showFlag(string $name, int $value) {
+    $all = Attribute::TARGET_ALL;
+    $and = $all & $value;
+    echo "Attribute::$name = $value ($all & $value === $and)\n";
+}
+
+showFlag("TARGET_CLASS", Attribute::TARGET_CLASS);
+showFlag("TARGET_FUNCTION", Attribute::TARGET_FUNCTION);
+showFlag("TARGET_METHOD", Attribute::TARGET_METHOD);
+showFlag("TARGET_PROPERTY", Attribute::TARGET_PROPERTY);
+showFlag("TARGET_CLASS_CONSTANT", Attribute::TARGET_CLASS_CONSTANT);
+showFlag("TARGET_PARAMETER", Attribute::TARGET_PARAMETER);
+showFlag("TARGET_CONSTANT", Attribute::TARGET_CONSTANT);
+showFlag("IS_REPEATABLE", Attribute::IS_REPEATABLE);
+
+$all = Attribute::TARGET_CLASS | Attribute::TARGET_FUNCTION
+    | Attribute::TARGET_METHOD | Attribute::TARGET_PROPERTY
+    | Attribute::TARGET_CLASS_CONSTANT | Attribute::TARGET_PARAMETER
+    | Attribute::TARGET_CONSTANT;
+var_dump($all, Attribute::TARGET_ALL, $all === Attribute::TARGET_ALL);
+
+?>
+--EXPECT--
+Attribute::TARGET_CLASS = 1 (127 & 1 === 1)
+Attribute::TARGET_FUNCTION = 2 (127 & 2 === 2)
+Attribute::TARGET_METHOD = 4 (127 & 4 === 4)
+Attribute::TARGET_PROPERTY = 8 (127 & 8 === 8)
+Attribute::TARGET_CLASS_CONSTANT = 16 (127 & 16 === 16)
+Attribute::TARGET_PARAMETER = 32 (127 & 32 === 32)
+Attribute::TARGET_CONSTANT = 64 (127 & 64 === 64)
+Attribute::IS_REPEATABLE = 128 (127 & 128 === 0)
+int(127)
+int(127)
+bool(true)

Zend/tests/attributes/constants/allow_named_parameters.phpt

@@ -0,0 +1,39 @@
+--TEST--
+Verify that named parameters can be passed to attributes on constants
+--FILE--
+<?php
+
+#[Attribute]
+class MyAttribute {
+    public function __construct($first, $second) {
+        echo "first: $first\n";
+        echo "second: $second\n";
+    }
+}
+
+#[MyAttribute(second: "bar", first: "foo")]
+const EXAMPLE = 'ignored';
+
+$ref = new ReflectionConstant('EXAMPLE');
+$attribs = $ref->getAttributes();
+var_dump($attribs);
+var_dump($attribs[0]->getArguments());
+$attribs[0]->newInstance();
+
+?>
+--EXPECTF--
+array(1) {
+  [0]=>
+  object(ReflectionAttribute)#%d (1) {
+    ["name"]=>
+    string(11) "MyAttribute"
+  }
+}
+array(2) {
+  ["second"]=>
+  string(3) "bar"
+  ["first"]=>
+  string(3) "foo"
+}
+first: foo
+second: bar

Zend/tests/attributes/constants/ast_export.phpt

@@ -0,0 +1,34 @@
+--TEST--
+AST can be recreated when constants have attributes
+--EXTENSIONS--
+zend_test
+--FILE--
+<?php
+
+#[MyAttrib]
+const WITH_ATTRIBUTE = true;
+
+#[First]
+#[Second]
+const WITH_UNGROUPED = true;
+
+#[First, Second]
+const WITH_GROUPED = true;
+
+#[MyAttrib(5, param: "example")]
+const WITH_PARAMETERS = true;
+
+echo zend_test_compile_to_ast(file_get_contents(__FILE__));
+
+?>
+--EXPECT--
+#[MyAttrib]
+const WITH_ATTRIBUTE = true;
+#[First]
+#[Second]
+const WITH_UNGROUPED = true;
+#[First, Second]
+const WITH_GROUPED = true;
+#[MyAttrib(5, param: 'example')]
+const WITH_PARAMETERS = true;
+echo zend_test_compile_to_ast(file_get_contents(__FILE__));

Zend/tests/attributes/constants/constant_listed_as_target-internal.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Constants listed in valid targets when used wrong (internal attribute)
+--FILE--
+<?php
+
+#[Deprecated]
+class Example {}
+
+?>
+--EXPECTF--
+Fatal error: Attribute "Deprecated" cannot target class (allowed targets: function, method, class constant, constant) in %s on line %d

Zend/tests/attributes/constants/constant_listed_as_target-userland.phpt

@@ -0,0 +1,31 @@
+--TEST--
+Constants listed in valid targets when used wrong (userland attribute)
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CONSTANT)]
+class MyConstantAttribute {}
+
+#[MyConstantAttribute]
+class Example {}
+
+$ref = new ReflectionClass(Example::class);
+$attribs = $ref->getAttributes();
+var_dump($attribs);
+$attribs[0]->newInstance();
+
+?>
+--EXPECTF--
+array(1) {
+  [0]=>
+  object(ReflectionAttribute)#%d (1) {
+    ["name"]=>
+    string(19) "MyConstantAttribute"
+  }
+}
+
+Fatal error: Uncaught Error: Attribute "MyConstantAttribute" cannot target class (allowed targets: constant) in %s:%d
+Stack trace:
+#0 %s(%d): ReflectionAttribute->newInstance()
+#1 {main}
+  thrown in %s on line %d

Zend/tests/attributes/constants/constant_redefined_addition.phpt

@@ -0,0 +1,21 @@
+--TEST--
+If a constant is redefined, attributes remain unchanged (no attributes)
+--FILE--
+<?php
+
+const MY_CONST = "No attributes";
+
+#[\MyAttribute]
+const MY_CONST = "Has attributes";
+
+echo MY_CONST . "\n";
+
+$reflection = new ReflectionConstant('MY_CONST');
+var_dump($reflection->getAttributes())
+
+?>
+--EXPECTF--
+Warning: Constant MY_CONST already defined in %s on line %d
+No attributes
+array(0) {
+}

Zend/tests/attributes/constants/constant_redefined_change.phpt

@@ -0,0 +1,27 @@
+--TEST--
+If a constant is redefined, attributes remain unchanged (different attributes)
+--FILE--
+<?php
+
+#[\MyAttribute]
+const MY_CONST = "Has attributes (1)";
+
+#[\MyOtherAttribute]
+const MY_CONST = "Has attributes (2)";
+
+echo MY_CONST . "\n";
+
+$reflection = new ReflectionConstant('MY_CONST');
+var_dump($reflection->getAttributes())
+
+?>
+--EXPECTF--
+Warning: Constant MY_CONST already defined in %s on line %d
+Has attributes (1)
+array(1) {
+  [0]=>
+  object(ReflectionAttribute)#%d (1) {
+    ["name"]=>
+    string(11) "MyAttribute"
+  }
+}