Bug #72483 [NEW]: General error with inheritance/implementation and returning type

From: alan dot g-l at live dot fr Operating system: Debian 8.5 PHP version: 7.0.8 Package: Reproducible crash Bug Type: Bug Bug description:General error with inheritance/implementation and returning type Description: ------------ If you want to build a function that force to return its own instance, you simply set it as returning self. But when you want to extend it, then PHP will said that our new class is not compatible with the parent one if we are overloading it. So maybe the "static" keyword is the answer, as it will be evaluated when executing? Wrong, PHP does not except the "static" keyword. This problems are the same for both class inheritance and interface implementation. Test script: --------------- // Interfaces // Sample 1 // with "self" keyword interface MyInterface { public function myFunction(): self; } class MyClass implements MyInterface{ public function myFunction(): self { return $this; } } // Fatal error: Declaration of MyClass::myFunction(): MyClass must be compatible with MyInterface::myFunction(): MyInterface // Sample 2 // with "static" keyword interface MyInterface { public function myFunction(): static; } class MyClass implements MyInterface { public function myFunction(): static { return $this; } } // Parse error: syntax error, unexpected 'static' (T_STATIC) // Classes and inheritance // Sample 3 // with "self" keyword class MyClass { public function myFunction(): self { return $this; } } class MyClass2 extends MyClass { public function myFunction() : self { return $this; } } // Fatal error: Declaration of MyClass2::myFunction(): MyClass2 must be compatible with MyClass::myFunction(): MyClass // Sample 4 // with "static" keyword class MyClass { public function myFunction(): static { return $this; } } class MyClass2 extends MyClass { public function myFunction(): static { return $this; } } // Parse error: syntax error, unexpected 'static' (T_STATIC) Expected result: ---------------- I think that the "self" keyword should work, as MyClass implements MyInterface (or MyClass2 extends MyClass), so the first one is an instance of the second one. Anyway, we can imagine that my asumption is false. So why that "static" word would not work here? -- Edit bug report at https://bugs.php.net/bug.php?id=72483&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=72483&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=72483&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=72483&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=72483&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=72483&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=72483&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=72483&r=needscript Try newer version: https://bugs.php.net/fix.php?id=72483&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=72483&r=support Expected behavior: https://bugs.php.net/fix.php?id=72483&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=72483&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=72483&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=72483&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=72483&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=72483&r=dst IIS Stability: https://bugs.php.net/fix.php?id=72483&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=72483&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=72483&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=72483&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=72483&r=mysqlcfg