Missing "var is used uninitialized" warning?

[Georg-Johann Lay <avr@xxxxxxxx>]

Hi, compiled with -Wall -Wextra the wollowing lines don't complain about 
a being used uninitialized.  Tried with 4.5 and 4.6.  Am I missing 
something?

int func (void)
{
    int a = a;

    return a;
}