Support first-class callables in const-expressions

NEWS

@@ -14,8 +14,8 @@ 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)
+  . Added support for Closures and first class callables in constant
+    expressions. (timwolla, Volker Dusch)
   . Use `clock_gettime_nsec_np()` for high resolution timer on macOS
     if available. (timwolla)
   . Implement GH-15680 (Enhance zend_dump_op_array to properly represent

UPGRADING

@@ -85,8 +85,10 @@ PHP 8.5 UPGRADE NOTES
 
 - Core:
   . Closure is now a proper subtype of callable
-  . Added support for Closures in constant expressions.
+  . Added support for Closures and first class callables in constant
+    expressions.
     RFC: https://wiki.php.net/rfc/closures_in_const_expr
+    RFC: https://wiki.php.net/rfc/fcc_in_const_expr
   . Fatal Errors (such as an exceeded maximum execution time) now include a
     backtrace.
     RFC: https://wiki.php.net/rfc/error_backtraces_v2

Zend/tests/first_class_callable/constexpr/attributes.phpt

@@ -0,0 +1,50 @@
+--TEST--
+Allow defining FCC in attributes
+--EXTENSIONS--
+reflection
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class Attr {
+    public function __construct(public Closure $value) {
+        var_dump($value('abc'));
+    }
+}
+
+#[Attr(strrev(...))]
+#[Attr(strlen(...))]
+class C {}
+
+foreach ((new ReflectionClass(C::class))->getAttributes() as $reflectionAttribute) {
+    var_dump($reflectionAttribute->newInstance());
+}
+
+?>
+--EXPECTF--
+string(3) "cba"
+object(Attr)#%d (1) {
+  ["value"]=>
+  object(Closure)#%d (2) {
+    ["function"]=>
+    string(6) "strrev"
+    ["parameter"]=>
+    array(1) {
+      ["$string"]=>
+      string(10) "<required>"
+    }
+  }
+}
+int(3)
+object(Attr)#%d (1) {
+  ["value"]=>
+  object(Closure)#%d (2) {
+    ["function"]=>
+    string(6) "strlen"
+    ["parameter"]=>
+    array(1) {
+      ["$string"]=>
+      string(10) "<required>"
+    }
+  }
+}

Zend/tests/first_class_callable/constexpr/attributes_ast_printing.phpt

@@ -0,0 +1,33 @@
+--TEST--
+AST printing for FCC in attributes
+--FILE--
+<?php
+
+// Do not use `false &&` to fully evaluate the function / class definition.
+
+try {
+    \assert(
+        !
+        #[Attr(strrev(...))]
+        function () { }
+    );
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    \assert(
+        !
+        new #[Attr(strrev(...))]
+        class {}
+    );
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+assert(!#[Attr(strrev(...))] function () {
+})
+assert(!new #[Attr(strrev(...))] class {
+})

Zend/tests/first_class_callable/constexpr/attributes_ast_printing_runtime.phpt

@@ -0,0 +1,27 @@
+--TEST--
+AST printing for FCC in attributes at runtime
+--FILE--
+<?php
+
+namespace Test;
+
+class Clazz {
+	#[Attr(strrev(...), \strrev(...), Clazz::foo(...), self::foo(...))]
+	function foo() { }
+}
+
+$r = new \ReflectionMethod(Clazz::class, 'foo');
+foreach ($r->getAttributes() as $attribute) {
+    echo $attribute;
+}
+
+?>
+--EXPECT--
+Attribute [ Test\Attr ] {
+  - Arguments [4] {
+    Argument #0 [ Test\strrev(...) ]
+    Argument #1 [ \strrev(...) ]
+    Argument #2 [ \Test\Clazz::foo(...) ]
+    Argument #3 [ self::foo(...) ]
+  }
+}

Zend/tests/first_class_callable/constexpr/attributes_scope_001.phpt

@@ -0,0 +1,28 @@
+--TEST--
+FCC in attribute may access private methods
+--EXTENSIONS--
+reflection
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class Attr {
+    public function __construct(public Closure $value) {}
+}
+
+#[Attr(C::myMethod(...))]
+class C {
+    private static function myMethod(string $foo) {
+        echo "Called ", __METHOD__, PHP_EOL;
+        var_dump($foo);
+    }
+}
+
+foreach ((new ReflectionClass(C::class))->getAttributes() as $reflectionAttribute) {
+    ($reflectionAttribute->newInstance()->value)('abc');
+}
+
+?>
+--EXPECT--
+Called C::myMethod
+string(3) "abc"

Zend/tests/first_class_callable/constexpr/attributes_scope_002.phpt

@@ -0,0 +1,34 @@
+--TEST--
+FCC in attribute may not access unrelated private methods
+--EXTENSIONS--
+reflection
+--FILE--
+<?php
+
+#[Attribute(Attribute::TARGET_CLASS | Attribute::IS_REPEATABLE)]
+class Attr {
+    public function __construct(public Closure $value) {}
+}
+
+class E {
+    private static function myMethod(string $foo) {
+        echo "Called ", __METHOD__, PHP_EOL;
+        var_dump($foo);
+    }
+}
+
+#[Attr(E::myMethod(...))]
+class C {
+}
+
+foreach ((new ReflectionClass(C::class))->getAttributes() as $reflectionAttribute) {
+    ($reflectionAttribute->newInstance()->value)('abc');
+}
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Call to private method E::myMethod() from scope C in %s:%d
+Stack trace:
+#0 %s(%d): ReflectionAttribute->newInstance()
+#1 {main}
+  thrown in %s on line %d

Zend/tests/first_class_callable/constexpr/autoload.phpt

@@ -0,0 +1,31 @@
+--TEST--
+FCC in const expression triggers autoloader.
+--FILE--
+<?php
+
+spl_autoload_register(static function ($class) {
+    echo "Autoloading {$class}", PHP_EOL;
+    eval(
+        <<<'EOT'
+            class AutoloadedClass {
+                public static function withStaticMethod() {
+                    echo "Called ", __METHOD__, PHP_EOL;
+                }
+            }
+            EOT
+    );
+});
+
+const Closure = AutoloadedClass::withStaticMethod(...);
+
+var_dump(Closure);
+(Closure)();
+
+?>
+--EXPECTF--
+Autoloading AutoloadedClass
+object(Closure)#%d (1) {
+  ["function"]=>
+  string(16) "withStaticMethod"
+}
+Called AutoloadedClass::withStaticMethod

Zend/tests/first_class_callable/constexpr/basic.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Allow defining FCC in const expressions.
+--FILE--
+<?php
+
+const Closure = strrev(...);
+
+var_dump(Closure);
+var_dump((Closure)("abc"));
+
+?>
+--EXPECTF--
+object(Closure)#%d (2) {
+  ["function"]=>
+  string(%d) "%s"
+  ["parameter"]=>
+  array(1) {
+    ["$string"]=>
+    string(10) "<required>"
+  }
+}
+string(3) "cba"

Zend/tests/first_class_callable/constexpr/case_insensitive.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Allow defining FCC in const expressions with case-insensitive names.
+--FILE--
+<?php
+
+const Closure = StrRev(...);
+
+var_dump(Closure);
+var_dump((Closure)("abc"));
+
+?>
+--EXPECTF--
+object(Closure)#%d (2) {
+  ["function"]=>
+  string(%d) "%s"
+  ["parameter"]=>
+  array(1) {
+    ["$string"]=>
+    string(10) "<required>"
+  }
+}
+string(3) "cba"

Zend/tests/first_class_callable/constexpr/class_const.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Allow defining FCC in class constants.
+--FILE--
+<?php
+
+class C {
+    const Closure = strrev(...);
+}
+
+var_dump(C::Closure);
+var_dump((C::Closure)("abc"));
+
+?>
+--EXPECTF--
+object(Closure)#%d (2) {
+  ["function"]=>
+  string(6) "strrev"
+  ["parameter"]=>
+  array(1) {
+    ["$string"]=>
+    string(10) "<required>"
+  }
+}
+string(3) "cba"

Zend/tests/first_class_callable/constexpr/complex_array.phpt

@@ -0,0 +1,39 @@
+--TEST--
+Allow defining FCC wrapped in an array in const expressions.
+--FILE--
+<?php
+
+const Closure = [strrev(...), strlen(...)];
+
+var_dump(Closure);
+
+foreach (Closure as $closure) {
+    var_dump($closure("abc"));
+}
+
+?>
+--EXPECTF--
+array(2) {
+  [0]=>
+  object(Closure)#%d (2) {
+    ["function"]=>
+    string(6) "strrev"
+    ["parameter"]=>
+    array(1) {
+      ["$string"]=>
+      string(10) "<required>"
+    }
+  }
+  [1]=>
+  object(Closure)#%d (2) {
+    ["function"]=>
+    string(6) "strlen"
+    ["parameter"]=>
+    array(1) {
+      ["$string"]=>
+      string(10) "<required>"
+    }
+  }
+}
+string(3) "cba"
+int(3)

Zend/tests/first_class_callable/constexpr/default_args.phpt

@@ -0,0 +1,18 @@
+--TEST--
+FCC in default argument
+--FILE--
+<?php
+
+function test(
+    Closure $name = strrev(...)
+) {
+    var_dump($name("abc"));
+}
+
+test();
+test(strlen(...));
+
+?>
+--EXPECT--
+string(3) "cba"
+int(3)

Zend/tests/first_class_callable/constexpr/error_abstract.phpt

@@ -0,0 +1,20 @@
+--TEST--
+FCC in initializer errors for FCC on abstract method
+--FILE--
+<?php
+
+abstract class Foo {
+    abstract public static function myMethod(string $foo);
+}
+
+const Closure = Foo::myMethod(...);
+
+var_dump(Closure);
+(Closure)("abc");
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Cannot call abstract method Foo::myMethod() in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d

Zend/tests/first_class_callable/constexpr/error_dynamic_001.phpt

@@ -0,0 +1,12 @@
+--TEST--
+FCC in initializer errors for FCC on variable.
+--FILE--
+<?php
+
+const Closure = $foo(...);
+
+var_dump(Closure);
+
+?>
+--EXPECTF--
+Fatal error: Cannot use dynamic function name in constant expression in %s on line %d