feat: allow hooks for backed properties

Author: NickSdot

Zend/tests/property_hooks/gh15419_1.phpt

@@ -1,12 +1,73 @@
 --TEST--
-Hooked properties cannot be readonly
+Backed readonly property may have nice hooks
 --FILE--
 <?php
 
-class Test {
-    public readonly int $prop { get; set; }
+// class readonly
+final readonly class Foo
+{
+    public function __construct(
+        public array $values {
+            set(array $value) => array_map(strtoupper(...), $value);
+        },
+    ) {}
 }
 
+// property readonly
+final class Foo2
+{
+    public function __construct(
+        public readonly array $values {
+            set(array $value) => array_map(strtoupper(...), $value);
+        },
+    ) {}
+}
+
+// redundant readonly
+final readonly class Foo3
+{
+    public function __construct(
+        public readonly array $values {
+            set(array $value) => array_map(strtoupper(...), $value);
+            get => $this->makeNicer($this->values);
+        },
+    ) {}
+
+    public function makeNicer(array $entries): array
+    {
+      return array_map(
+        fn($i, $entry) => $entry . strtoupper(['', 'r', 'st'][$i]), array_keys($entries),
+        $entries
+       );
+    }
+}
+
+\var_dump(new Foo(['yo,', 'you', 'can'])->values);
+\var_dump(new Foo2(['just', 'do', 'things'])->values);
+\var_dump(new Foo3(['nice', 'nice', 'nice'])->values);
 ?>
---EXPECTF--
-Fatal error: Hooked properties cannot be readonly in %s on line %d
+--EXPECT--
+array(3) {
+  [0]=>
+  string(3) "YO,"
+  [1]=>
+  string(3) "YOU"
+  [2]=>
+  string(3) "CAN"
+}
+array(3) {
+  [0]=>
+  string(4) "JUST"
+  [1]=>
+  string(2) "DO"
+  [2]=>
+  string(6) "THINGS"
+}
+array(3) {
+  [0]=>
+  string(4) "NICE"
+  [1]=>
+  string(5) "NICER"
+  [2]=>
+  string(6) "NICEST"
+}

Zend/tests/property_hooks/gh15419_2.phpt

@@ -0,0 +1,70 @@
+--TEST--
+Backed readonly property may have hooks
+--FILE--
+<?php
+
+// readonly property
+class Test1 {
+    public readonly int $prop {
+        get => $this->prop;
+        set => $value;
+    }
+
+    public function __construct(int $v) {
+        $this->prop = $v;
+    }
+}
+
+$t = new Test1(42);
+var_dump($t->prop);
+try {
+    $t->prop = 43;
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+// readonly class
+readonly class Test2 {
+    public int $prop {
+        get => $this->prop;
+        set => $value;
+    }
+
+    public function __construct(int $v) {
+        $this->prop = $v;
+    }
+}
+
+$t = new Test2(42);
+var_dump($t->prop);
+try {
+    $t->prop = 43;
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+// readonly class, promoted
+readonly class Test3 {
+    public function __construct(
+        public int $prop {
+            get => $this->prop;
+            set => $value;
+        }
+    ) {}
+}
+
+$t = new Test3(42);
+var_dump($t->prop);
+try {
+    $t->prop = 43;
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+?>
+--EXPECT--
+int(42)
+Cannot modify protected(set) readonly property Test1::$prop from global scope
+int(42)
+Cannot modify protected(set) readonly property Test2::$prop from global scope
+int(42)
+Cannot modify protected(set) readonly property Test3::$prop from global scope

Zend/tests/property_hooks/readonly.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Virtual readonly property cannot have hooks
+--FILE--
+<?php
+
+class Test {
+    public readonly int $prop {
+        get => 42;
+    }
+}
+?>
+--EXPECTF--
+Fatal error: Hooked virtual properties cannot be readonly in %s on line %d

Zend/tests/property_hooks/readonly_backed_property.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Virtual promoted property in readonly class cannot have hooks
+--FILE--
+<?php
+
+readonly class Test {
+    public function __construct(
+        public int $prop {
+            get => 42;
+        }
+    ) {}
+}
+
+?>
+--EXPECTF--
+Fatal error: Hooked virtual properties cannot be readonly in %s on line %d

Zend/tests/property_hooks/readonly_virtual_property.phpt

@@ -8497,8 +8497,9 @@ static void zend_compile_property_hooks(
 {
 	zend_class_entry *ce = CG(active_class_entry);
 
-	if (prop_info->flags & ZEND_ACC_READONLY) {
-		zend_error_noreturn(E_COMPILE_ERROR, "Hooked properties cannot be readonly");
+	/* Allow hooks on backed readonly properties only. */
+	if ((prop_info->flags & (ZEND_ACC_READONLY|ZEND_ACC_VIRTUAL)) == (ZEND_ACC_READONLY|ZEND_ACC_VIRTUAL)) {
+		zend_error_noreturn(E_COMPILE_ERROR, "Hooked virtual properties cannot be readonly");
 	}
 
 	if (hooks->children == 0) {