Incorrect result with redeclared class when JIT

[YuanchengJiang]

Description

The following code:

<?php
echo "this should be called twice!\n";

class Example {} // will be redeclared

if (defined("test")) {
  echo "end\n";
} else {
  define("test", 1);
  echo("now include myself\n");
  include(__FILE__);
}
?>

Resulted in this output:

this should be called twice!
now include myself

Fatal error: Cannot redeclare class Example (previously declared in /tmp/x.php:4) in /tmp/x.php on line 4

But I expected this output instead:

this should be called twice!
now include myself
this should be called twice!

Fatal error: Cannot redeclare class Example (previously declared in /tmp/x.php:4) in /tmp/x.php on line 4

To reproduce:

-d "zend_extension=/php-src/modules/opcache.so" -d "opcache.enable_cli=1" -d "opcache.enable=1"

It seems the error goes before the next execution in JIT so that it does not echo twice?

PHP Version

nightly

Operating System

ubuntu 22.04

[YuanchengJiang]

The first execution in JIT mode might print twice. After you execute it for many times, I suppose after it is cached, it only echoes once.

[cmb69]

This is not related to JIT (not that OPcache does not imply JIT). Anyhow, simplified explanation:

Without OPcache, the script is compiled, and run; the include triggers a second compilation of the file, and a second run. Only when the engine sees the class declaration (DECLARE_CLASS), it complains; at that point the echo statement has already been executed.

With OPcache, the script is compiled, cached and then run; the include fetches the file from the cache, tries to register the class, and sees that the class has already been registered, so errors out; and that before any attempt is made to run the script again.

Such differences are to be expected if you mix declarations and statements in a file. PSR-1 says that declarations and side-effects (aka. statements) shold not be mixed. And if you still want to mix them, I suggest to put declarations at the top, and statements at the bottom of file.