Description:
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When constructing a variable name using the $$foo syntax, it is only possible to reference a superglobal in this way from outside a function. Inside a function it appears to reference a variable with the same name that is local to the function.

In other words, the code
$foo='_REQUEST';
print (${$foo}['bar']);
behaves differently within a function and within the main loop.

I've been able to reproduce this bug on several servers with different configurations. 4.3.10 is the latest version I have available to test.

Reproduce code:
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Demonstration
http://www.dur.ac.uk/c.i.morris/superglobals.php?foo=123

Source code
http://www.dur.ac.uk/c.i.morris/superglobals.phps

[Note: this server is running an older version of PHP, but  the same effect happens on a non-public server running 4.3.10]

Expected result:
----------------
Out of the function:123

In the function:123


Actual result:
--------------
Out of the function:123

In the function: