Sometimes it has duplicated warning messages in return statements

[YuanchengJiang]

Description

The following code:

<?php
class A {
	function method(?int $a): ?int {
		return $i;    // it only warns once if return $i+$a
	}
}
$a = new A();
$a->method(1);
?>

Resulted in this output:

Warning: Undefined variable $i in test.php on line 4

Warning: Undefined variable $i in test.php on line 4

If this is expected, wondering why return $i+$a only warns once.

PHP Version

nightly

Operating System

ubuntu 22.04

[iluuu1994]

Interesting observation. For whatever reason, both the ZEND_VERIFY_RETURN_TYPE and ZEND_RETURN opcodes check for undefined variables.

[iluuu1994]

This is fixable in the VM by making ZEND_VERIFY_RETURN_TYPE only emit a warning if it will also throw an exception. However, the change isn't quite as straight-forward in the JIT. Since 9.0 will promote undefined variables to an error (https://wiki.php.net/rfc/undefined_variable_error_promotion), it doesn't seem worth fixing at this point. Thank you for the report nonetheless!