[R-SIG-Mac] Which command line tools for XCode 4.2.1

[cstrato]

Dear Prof. Ripley, dear Simon,

Thank you for this information about Xcode and CLTs.

Since I have heard that R and Bioconductor packages should in the future 
be built with clang since Apple will be discontinuing support of gcc, my 
question is:

- Which version of Xcode and/or CLTs should Snow Leopard users install 
in the future? (the last official version for Snow Leopard is xcode_3.2.6)

- Which version of Xcode and/or CLTs should Lion/Mountain Lion users 
install so that they can still compile their packages with gcc, too?
(the current version is xcode_4.6.2)

 From the discussion I understand that it is no longer necessary to 
install Xcode at all, installing CLTs is sufficient. Is this  correct?

Best regards,
Christian