Does findlib support the autolink feature of OCaml 3?

Short answer: Findlib is compatible with autolink

The new archive format introduced with OCaml 3 can store the linker options that are necessary to link an archive. For example:

ocamlc -a -o myarchive.cma mymodule.cmo -cclib -lmylibrary

This command does not only create the new archive myarchive.cma, but it also writes into a special section of that file that the linker option -cclib -lmylibrary is necessary to link this archive.

This means for findlib that most of the "linkopts" attributes in META files have become superfluous: The compiler itself already knows the linker options, we do not need to tell the compiler the options. We could simply leave all "linkopts" attributes out.

Of course, the "linkopts" feature of findlib still works. This is necessary because findlib should keep the compatibility with older software, and because "linkopts" is more powerful (you can have conditional linker options).

If you have software that must run in both OCaml 2 and OCaml 3 environments, you can make your "linkopts" attribute dependent on the "autolink" predicate. For example:

linkopts = "-cclib -lmylibrary"
linkopts(autolink) = ""

The findlib installation for OCaml 3 will take the second line which is reasonable because ocamlc already knows how to link; the installation for OCaml 2 never sets the "autolink" predicate and therefore uses the first line.