Namely, switched in many places to using GNU make provided functions
for directory listing and text processing, rather than spawning a
shell process to do that work.
In the process of the revision, learned about Target-specific
variables, which were very applicable to INSTALL_LIB (which, on a
per-recipe basis, was always receiving the same actual arguments for
its first two formal parameters in every invocation).
http://www.gnu.org/software/make/manual/html_node/Target_002dspecific.html
(We might be able to make use of those in future refactorings.)
----
Also adds a cleanup pass to get-snapshot.py as well, since the same
problem arises when we unpack libraries from the snapshot archive into
a build directory with a prior snapshot's artifacts. (I put this step
into the python script rather than the makefile because I wanted to
delay the cleanup pass until after we have at least successfully
downloaded the tarball. That way, if the download fails, you should
not destroy the previous unarchived snapshot libraries and build
products.)
----
Also reverted whitespace changes to minimize diff.
I plan to put them back in in a dedicated commit elsewhere.
When building Rust libraries (e.g. librustc, libstd, etc), checks for
and verbosely removes previous build products before invoking rustc.
(Also, when Make variable VERBOSE is defined, it will list all of the
libraries matching the object library's glob after the rustc
invocation has completed.)
When installing Rust libraries, checks for previous libraries in
target install directory, but does not remove them.
The thinking behind these two different modes of operation is that the
installation target, unlike the build tree, is not under the control
of this infrastructure and it is not up to this Makefile to decide if
the previous libraries should be removed.
This way a cross-compiled rustc's answer to host_triple() is correct. The return
value of host_triple() reflects the actual host triple that the compiler was
build for, not the triple the compiler is being built on
This lets us use #ifdefs to determine which stage of the build we happen
to be in, which is useful in the event we need to make changes to rustrt
that are incompatible with the code generated by stage0.
This should help pave the way to completing #6575, which will likely
require changes to type signatures for spawn_fn & glue_fn in rustrt.
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
