Emit readonly classes natively in PHP 8.3

Author: thekid

ChangeLog.md

@@ -3,6 +3,10 @@ XP Compiler ChangeLog
 
 ## ?.?.? / ????-??-??
 
+* Changed emitter to use native readonly classes in PHP 8.3, fixing an
+  inconsistency with accessing undefined properties
+  (@thekid)
+
 ## 9.2.0 / 2024-08-27
 
 * Merged PR #183: Add emitting support for asymmetric visibility. See

src/main/php/lang/ast/emit/PHP83.class.php

@@ -18,7 +18,7 @@
  * @see  https://wiki.php.net/rfc#php_83
  */
 class PHP83 extends PHP {
-  use RewriteBlockLambdaExpressions, RewriteProperties, ReadonlyClasses;
+  use RewriteBlockLambdaExpressions, RewriteProperties;
 
   public $targetVersion= 80300;
 

src/main/php/lang/ast/emit/ReadonlyClasses.class.php

@@ -33,9 +33,11 @@ protected function emitClass($result, $class) {
       }
 
       // Prevent dynamic members
-      $throw= new Code('throw new \\Error("Cannot create dynamic property ".__CLASS__."::".$name);');
       $context= $result->codegen->enter(new InType($class));
-      $context->virtual[null]= [$throw, $throw];
+      $context->virtual[null]= [
+        new Code('trigger_error("Undefined property: ".__CLASS__."::\$".$name, E_USER_WARNING); return $_;'),
+        new Code('throw new \\Error("Cannot create dynamic property ".__CLASS__."::".$name);')
+      ];
     }
 
     return parent::emitClass($result, $class);

src/test/php/lang/ast/unittest/emit/ReadonlyTest.class.php

@@ -174,10 +174,11 @@ public function cannot_have_an_initial_value() {
     }');
   }
 
-  #[Test, Expect(class: Error::class, message: '/Cannot create dynamic property .+fixture/')]
-  public function cannot_read_dynamic_members_from_readonly_classes() {
+  #[Test]
+  public function reading_dynamic_members_from_readonly_classes_causes_warning() {
     $t= $this->declare('readonly class %T { }');
-    $t->newInstance()->fixture;
+    Assert::null($t->newInstance()->fixture);
+    \xp::gc();
   }
 
   #[Test, Expect(class: Error::class, message: '/Cannot create dynamic property .+fixture/')]