Description:
------------
In an anonymous function, the use clause does not accept a variable that is denoted as ${'variable'}, whereas the equivalent $variable of course works.

See test script below. 

Test script:
---------------
$x = 1; // global scope

$printGlob = function() use ($x) {
	echo "x = $x".PHP_EOL;
};

$printGlob();	// success, prints x = 1

$x = 2;

$printGlob2 = function() use (${'x'}) {
// Preceeding line yields: 
// Parse error: syntax error, unexpected '$', expecting '&' or variable (T_VARIABLE)	
	echo "x2 = $x".PHP_EOL;
};

$printGlob2();	// Should parse, and yield x2 = 2

Expected result:
----------------
$f = function() use ($var) { ... };
and
$f = function() use (${'var'}) { ... }; 
should be considered equivalent and therefore parse properly.


Actual result:
--------------
See test script. 
$f = function() use (${'var'}) { ... }; 
yields a parse error, which in addition is quite confusing.