This is an attempt to address Issue #3326 by adding [*order-only*][1]
prerequsites of each build product on the directory where it is to go.
It is important that the prerequisites be order-only, since the
timestamp on a parent directory is not relevant to whether a product
is out of date; the parent directory merely needs to exist.
(This use case of generating target directories was provided as an
[example][2] of how order-only prequisites are used.)
[1]: http://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html
[2]: http://www.kolpackov.net/pipermail/notes/2004-January/000001.html
r? @pcwalton
Sorry this is so big, and sorry the first commit is just titled 'wip'.
Some interesting bits
* [LocalServices](f9069baa70) - This is the set of runtime capabilities that *all* Rust code should expect access to, including the local heap, GC, logging, unwinding.
* [impl Reader, etc. for Option](5fbb0949a5) - Constructors like `File::open` return Option<FileStream>. This lets you write I/O code without ever unwrapping an option.
This series adds a lot of [documentation](https://github.com/brson/rust/blob/io/src/libcore/rt/io/mod.rs#L11) to `core::rt::io`.
Even more of `core::run` could be rust-ified -- I believe that access to the C extern environ can be done with rust now. I did not do this because some special casing is needed for OSX and I don't have a mac I can test with.
I think this will also fix#6096.
Recent demoding makes the visitor glue leak. It hasn't shown up in tests
because the box annihilator deletes the leaked boxes. This affects the
new scheduler though which does not yet have a box annihilator.
I don't think there's any great way to test this besides setting up
a task that doesn't run the box annihilator and I don't know that that's
a capability we want tasks to have.
Lots of linking arguments need to be passed as -Wl,--foo so giving the
comma meaning at the rustc layer makes those flags impossible to pass.
Multiple arguments can now be passed from a shell by quoting the
argument: --link-args='-lfoo -Wl,--as-needed'.
I don't know how one would write a separate test for this sort of thing. Building the compiler, and `make check` worked, which should mean I didn't screw anything.
- it is now cross platform, instead of just unix
- it now avoids sleeping (fixing issue #6156)
- it now calls force_destroy() when force = true (was a bug)
