[PHP-BUG] Bug #77100 [NEW]: Inconsistent behavior between constants and magic constants

From:             fabien dot villepinte at gmail dot com
Operating system: 
PHP version:      Irrelevant
Package:          PHP Language Specification
Bug Type:         Bug
Bug description:Inconsistent behavior between constants and magic constants

Description:
------------
The functions define(), defined() and constant() don't work the same way
whether the name of the constant given as an argument is the name of an
already defined constant or the name of a magic constant.

For instance :
define('PHP_EOL', 0); // returns false and emits a notice
define('__DIR__', 0); // returns true
__DIR__; // returns the path of the current directory
constant('__DIR__'); // returns the value of the user-defined constant,
0 in this case

There is nothing in the documentation mentioning this case, so I can't
say if the current behavior is correct or not.

Test script:
---------------
<?php
var_dump(defined('__LINE__'));
var_dump(define('__LINE__', 'test'));
var_dump(constant('__LINE__'));
var_dump(__LINE__);

Actual result:
--------------
bool(false)
bool(true)
string(4) "test"
int(5)

-- 
Edit bug report at https://bugs.php.net/bug.php?id=77100&edit=1
-- 
Try a snapshot (PHP 5.4):   https://bugs.php.net/fix.php?id=77100&r=trysnapshot54
Try a snapshot (PHP 5.5):   https://bugs.php.net/fix.php?id=77100&r=trysnapshot55
Try a snapshot (trunk):     https://bugs.php.net/fix.php?id=77100&r=trysnapshottrunk
Fixed in SVN:               https://bugs.php.net/fix.php?id=77100&r=fixed
Fixed in release:           https://bugs.php.net/fix.php?id=77100&r=alreadyfixed
Need backtrace:             https://bugs.php.net/fix.php?id=77100&r=needtrace
Need Reproduce Script:      https://bugs.php.net/fix.php?id=77100&r=needscript
Try newer version:          https://bugs.php.net/fix.php?id=77100&r=oldversion
Not developer issue:        https://bugs.php.net/fix.php?id=77100&r=support
Expected behavior:          https://bugs.php.net/fix.php?id=77100&r=notwrong
Not enough info:            https://bugs.php.net/fix.php?id=77100&r=notenoughinfo
Submitted twice:            https://bugs.php.net/fix.php?id=77100&r=submittedtwice
register_globals:           https://bugs.php.net/fix.php?id=77100&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=77100&r=php4
Daylight Savings:           https://bugs.php.net/fix.php?id=77100&r=dst
IIS Stability:              https://bugs.php.net/fix.php?id=77100&r=isapi
Install GNU Sed:            https://bugs.php.net/fix.php?id=77100&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=77100&r=float
No Zend Extensions:         https://bugs.php.net/fix.php?id=77100&r=nozend
MySQL Configuration Error:  https://bugs.php.net/fix.php?id=77100&r=mysqlcfg