Req #70761 [NEW]: Fatal error if missing parent class - create "stub" class instead

From: andreas at dqxtech dot net Operating system: Linux PHP version: 7.0.0RC5 Package: PHP Language Specification Bug Type: Feature/Change Request Bug description:Fatal error if missing parent class - create "stub" class instead Description: ------------ (similar to https://bugs.php.net/bug.php?id=53036&edit=2, but more relevant issue summary - * see below) Currently if a script wants to declare a class, and inherit from a missing parent class, a fatal error will occur. This causes problems with class_exists() + autoload: - If class C cannot be autoloaded, then class_exists('C') will simply return false. - If class C can be autoloaded, but the parent class P can not, then class_exists('C') will include the file that defines C, which triggers a fatal error because P does not exist and cannot be autoloaded. Typical scenario: - Library LibC contains a class C with parent class P, where P is defined in another library LibP. - Library LibC does NOT explicitly depend on LibP. Instead, the class C should only be used if LibP is installed in the project. We could say, LibP is an "optional dependency" of LibC. - A discovery algorithm scans LibC for useful classes, and tries "class_exists('C')", or explicitly includes the file defining C -> fatal error, because P is missing. Instead, such discovery algorithms nowadays need to use PHP parsing and stuff like Doctrine's StaticReflectionParser. https://github.com/doctrine/common/blob/master/lib/Doctrine/Common/Reflection/StaticReflectionParser.php Solution: - Instead of a fatal, simply behave as if the class C is not defined. So, class_exists('C') should return FALSE. - Internally remember the "stub" definition of C. - If class_exists('C') is called again, and autoloading for 'C' would be triggered again, instead trigger the autoload for 'P' and attempt to complete the stub definition of C. - Provide a new language feature to test for "stub" class definitions. --------- * Why a new issue, and not comment on https://bugs.php.net/bug.php?id=53036&edit=2 ? The other issue paints this as a problem with class_exists() + autoload. But solution is to change the behavior of include(), independent of class_exists() + autoload. The description and code example in this issue focuses directly on the include(). I expect this to allow for a more focused discussion. Test script: --------------- // Assuming class P does not exist and cannot be autoloaded either. class C extends P {} print class_exists('C') ? 'yes' : 'no'; Expected result: ---------------- 'no' (because C has a non-existing base class) Actual result: -------------- PHP Fatal error: Class 'P' not found [..] (triggered by the class definition, NOT by the class_exists()) -- Edit bug report at https://bugs.php.net/bug.php?id=70761&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=70761&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=70761&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=70761&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=70761&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=70761&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=70761&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=70761&r=needscript Try newer version: https://bugs.php.net/fix.php?id=70761&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=70761&r=support Expected behavior: https://bugs.php.net/fix.php?id=70761&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=70761&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=70761&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=70761&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=70761&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=70761&r=dst IIS Stability: https://bugs.php.net/fix.php?id=70761&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=70761&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=70761&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=70761&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=70761&r=mysqlcfg