Run rustc for information fewer times
#5249
Conversation
|
r? @matklad (rust_highfive has picked a reviewer for you, use r? to override) |
| @@ -246,11 +246,17 @@ impl<'a, 'cfg> Context<'a, 'cfg> { | |||
| /// all the units mentioned in `units`. | |||
| pub fn probe_target_info(&mut self) -> CargoResult<()> { | |||
| debug!("probe_target_info"); | |||
| self.probe_target_info_kind(Kind::Target)?; | |||
| if self.requested_target().is_none() { | |||
There was a problem hiding this comment.
Hm, interesting, so the previous logic kinda handled this in the case where target was not passed at all....
Perhaps add a helper Context::is_cross_compiling which handles both "no target" and "explicit target the same as the host", so that we don't duplicated this logic incorrectly elsewhere?
There was a problem hiding this comment.
I'm gonna hold off on this suggestion for now because the deduction here is different than Cargo's historical deduction of "am I cross compiling?" (aka is --target passed?). I'd hope though we could improve this in the future!
| self.host_info = self.target_info.clone(); | ||
| } else { | ||
| self.probe_target_info_kind(Kind::Host)?; | ||
| self.probe_target_info_kind(Kind::Target)?; |
There was a problem hiding this comment.
Oh, actually this side-effectual mutating API looks horrible to me :) Do you feel like refactoring it to
self.host_info = self.probe_target_info_kind(Kind::Host);
self.target_info = if host_target_same {
self.host_info.clone()
} else {
self.probe_target_info_kind(Kind::Target)
}?
|
Hm, what about normalizing and will build everything twice, because the command line and thus the fingerprints would differ. |
Currently if you pass `--target` the same as rustc's host Cargo will run `rustc` on extra time to learn information, but we only need to run it once to learn such information!
alexcrichton
force-pushed
the
run-rustc-less
branch
from
410adfa
to
0eb7edf
Compare
|
Updated! Leaving out the normalization for now as I think it runs the risk for breakage, but we can fix that later for sure I think. |
|
@bors r+ |
|
📌 Commit 0eb7edf has been approved by |
Run `rustc` for information fewer times Currently if you pass `--target` the same as rustc's host Cargo will run `rustc` on extra time to learn information, but we only need to run it once to learn such information!
|
☀️ Test successful - status-appveyor, status-travis |
One hard cs problem Closes #5313 r? @alexcrichton Note that, due to the first commit, this still gives us all the benefits of #5249: if RUSTFLAGS is empty, we will run only a single rustc process, even if we can't cache it across different cargo invocations.
Currently if you pass
--targetthe same as rustc's host Cargo will runrustcon extra time to learn information, but we only need to run it once to learn
such information!