[boost] Which compilers are not supported for 1.48 ?

Are really old and broken compilers still supported? Do we need them? For example VC++6. It gives thousands of warnings on type_traits and boost PP headers. Tests for VC++6 do not compile. Nobody tested boost libraries on that compiler for years. May be we shall get rid of compilers, that do not support template partitial specialization, ADL or SFINAE? If not, shall we try to make the tests pass (or at least compile) for them? Best regards, Antony Polukhin