Why is "-std=c++0x" still needed for g++ 4.6.2? [closed]

Question

I downloaded and built gcc 4.6.2. I find that for C++11 features, the command line option -std=c++0x is still needed. Why is that? Isn't is supposed to support it by default?

    $ g++ --version
    g++ (GCC) 4.6.2
    Copyright (C) 2011 Free Software Foundation, Inc.
    This is free software; see the source for copying conditions.  There is NO
    warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Answer 1

Because

• C++11 is only 4 Months old and support for it is far from being complete or tested
• changing the default without a big announcement and preparation phase for people is not nice
• It is not clear if the default will ever change (see -std=C99).