i18n extract: parseClassName() treats ::class as a class declaration #19579

Description

bin/cake i18n extract warns about classes that do not exist. On a stock install the warnings come from CakePHP's own source, which is scanned to build cake.pot:

Could not reflect class/enum Cake\Core\TestSuite\Router in file src/Core/TestSuite/ContainerStubTrait.php: Class "Cake\Core\TestSuite\Router" does not exist
Could not reflect class/enum Cake\Event\true in file src/Event/EventListenerRegistrationTrait.php: Class "Cake\Event\true" does not exist

Cake\Event\true gives it away: a true literal is being read as a class name. Extraction still completes and the output is correct, so this is cosmetic — just noisy, especially in CI.

Cause

I18nExtractCommand::parseClassName() starts looking for a name as soon as it sees T_ENUM or T_CLASS:

if ($type === T_ENUM || $type === T_CLASS) {
    $waitingForName = true;
    continue;
}

if ($waitingForName && $type === T_STRING) {
    return $namespace !== '' ? $namespace . '\\' . $value : $value;
}

But T_CLASS is also the token for the ::class magic constant — Foo::class tokenizes as T_STRING, T_DOUBLE_COLON, T_CLASS. So in is_a($listener, EventListenerInterface::class, true) the parser hits T_CLASS, then takes the next T_STRING, which is true.

The second condition is that both files declare a trait. parseClassName() does not know T_TRAIT, so there is no real declaration to match first and the first ::class in the body wins:

The second also shows imports are not followed: the file has use Cake\Routing\Router;, but the name is glued to the file's own namespace. When such a guess happens to exist, no warning appears and the wrong class is reflected silently — harmless today only because extractFileReflection() drops anything that is not an enum.

Steps to reproduce

In any 5.4.1 app:

bin/cake i18n extract --extract-core yes --overwrite --paths src/,templates/ --output resources/locales/

--extract-core yes is the part that matters: it puts vendor/cakephp/cakephp/src/ in the scanned paths, and both offending files are there. Nothing in the app itself is needed to trigger it.

Expected

No warnings; a file declaring no class or enum is skipped.

Suggested fix

Track the previous significant token and ignore T_CLASS that follows T_DOUBLE_COLON:

-            if ($type === T_ENUM || $type === T_CLASS) {
+            // `Foo::class` produces T_CLASS as well, and is not a declaration
+            if (($type === T_ENUM || $type === T_CLASS) && $previous !== T_DOUBLE_COLON) {
                 $waitingForName = true;
                 continue;
             }

with $previous assigned on every branch that reaches the end of the loop body.

Running both versions over the two offending files plus a real enum and class:

Optionally, class_exists($fqn, false) before new ReflectionClass($fqn) would stop an unresolvable name from becoming an exception at all.

Environment

CakePHP 5.4.1, PHP 8.4.24. Still present on 5.x as of this writing.

CakePHP Version

5.4.1

PHP Version

8.4.24