Bug #69586 [NEW]: Resolution of static function variables not using forwarded calling information

From: php at lvl dot fastmail dot com Operating system: PHP version: 5.6.8 Package: Unknown/Other Function Bug Type: Bug Bug description:Resolution of static function variables not using forwarded calling information Description: ------------ I ran into some very strange behavior while experimenting with static function variables. Static variables in the function scope appear to be resolved using late static binding: the content of the variable in that function is shared amongst all instances of a class, though each subclass gets its own separate variable space. This is pretty logical and works fine. As an example, let's create classes Base => Animal => {Cat,Dog}. Base has a function that describes the class, and caches the result in a static function variable $description. Calling describe() on the three different classes correctly gives us three different results: http://3v4l.org/Qldve However, once you override the describe function in Animal and call parent::describe() from within, it looks like all calling information is lost: the resolution of $description in Base's function scope now always points to Animal's variable space. For example: http://3v4l.org/CcrL8 I would have expected the static function variable and get_called_class() to always refer to the same class/variable space, parent:: or not. Overriding the function in one of the childmost classes like Dog gives an even stranger result: $description is now correctly a separate value in Cat vs Dog, but calling Animal::describe() now uses the value left by its child class Cat?! See: http://3v4l.org/61P72 Test script: --------------- class Base { public static function describe() { echo "--> " . ($calculated = "I am a " . get_called_class() . "\n"); static $cached = null; if ($cached === null) { $cached = $calculated; } return $cached; } } class Animal extends Base { public static function describe() { return 'Hello! ' . parent::describe(); } } class Cat extends Animal { } class Dog extends Animal { } echo Cat::describe(); echo Dog::describe(); echo Animal::describe(); Expected result: ---------------- --> I am a Cat Hello! I am a Cat --> I am a Dog Hello! I am a Dog --> I am a Animal Hello! I am a Animal Actual result: -------------- --> I am a Cat Hello! I am a Cat --> I am a Dog Hello! I am a Cat --> I am a Animal Hello! I am a Cat -- Edit bug report at https://bugs.php.net/bug.php?id=69586&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=69586&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=69586&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=69586&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=69586&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=69586&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=69586&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=69586&r=needscript Try newer version: https://bugs.php.net/fix.php?id=69586&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=69586&r=support Expected behavior: https://bugs.php.net/fix.php?id=69586&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=69586&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=69586&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=69586&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=69586&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=69586&r=dst IIS Stability: https://bugs.php.net/fix.php?id=69586&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=69586&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=69586&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=69586&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=69586&r=mysqlcfg