Req #55493 [Com]: Superglobal variable variables with ${expression} in non-global scope

Edit report at https://bugs.php.net/bug.php?id=55493&edit=1 ID: 55493 Comment by: vovan-ve at yandex dot ru Reported by: vovan-ve at yandex dot ru Summary: Superglobal variable variables with ${expression} in non-global scope Status: Assigned Type: Feature/Change Request Package: Variables related Operating System: Windows XP SP3 PHP Version: 5.3.7 Assigned To: dmitry Block user comment: N Private report: N New Comment: When I tried to obfuscate a part of code I was surprised by this strange behariour. Of course, current implementation is correct on the one hand. But on the other hand the situation looks funny: this way is allowad, and this too, but this is not. Previous Comments: ------------------------------------------------------------------------ [2011-08-24 04:11:14] laruence@php.net sure, it can be fixed by decide target symbol table again in the execution time for not const OPs, but I don't think this is really necessary . :) ------------------------------------------------------------------------ [2011-08-23 18:16:12] kalle@php.net This still seems a little strange that we cannot pick the correct symbol table at compile time, all it should need would be a check to see if the compiled value is matching one thats a super global. I remember to have encountered something similar a while back, which I'm not sure if I reported or not, but def. something we should look into at some point. Dmitry, can you clarify this? ------------------------------------------------------------------------ [2011-08-23 16:49:00] laruence@php.net As I said, this is a limitation of PHP design, so mark as won't fix. Thank you for your interest in PHP. ------------------------------------------------------------------------ [2011-08-23 16:22:46] laruence@php.net when fetching a variable, the target symbol table is decided in compiling time, for the script above, in compiling time, only const string "_SERVER" can be took consider as a SUPERVAR and assign the global symbol table as target_symbol_table. the others varname only can be see in execution time, so Zend VM think it should be fetched from a local symbol table. and the 'local symbol table' for the global scope statement is actual 'global symbol table', therefor it works 'as expected'. ------------------------------------------------------------------------ [2011-08-23 14:14:42] vovan-ve at yandex dot ru Description: ------------ ONLY Superglobal variable variables does not work ONLY in non-global scope and ONLY with non-constant expression. See test script. I found Req 38527, but it does not describe the problem properly and due to misunderstanding it has status Feature Request instead of Bug (and also it is too old). Test script: --------------- // in global scope everything is right $name = '_SERVER'; var_dump( isset(${'_SERVER'}), isset($$name), isset(${$name}), isset(${'_SER' . 'VER'}), isset(${'na' . 'me'}) ); echo PHP_EOL; // but outside of global scope there is a trouble function f() { $name = '_SERVER'; var_dump( isset(${'_SERVER'}), isset($$name), isset(${$name}), isset(${'_SER' . 'VER'}), isset(${'na' . 'me'}) ); } f(); Expected result: ---------------- bool(true) bool(true) bool(true) bool(true) bool(true) bool(true) bool(true) bool(true) bool(true) bool(true) Actual result: -------------- bool(true) bool(true) bool(true) bool(true) bool(true) bool(true) bool(false) bool(false) bool(false) bool(true) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=55493&edit=1