option `-Weffc++' and libstdc++

[Dimitri PAPADOPOULOS-ORFANOS]

Option `-Weffc++' has been added:
	Warn about violation of some style rules from
	Effective C++ by Scott Myers.

Although this is an excellent idea, this option cannot be used.
I get hundreds of warning lines in libstdc++ (streams, STL, ...).
I cannot find warnings about my own code in this noise.

Should this option considered experimental?
Will the future versions of libstdc++ be corrected?