This commit continues the work from #9112 to enable `unpacked` split
debuginfo on macOS targets by default. This has been discussed on [internals]
for awhile now and no breakage has emerged while significant speedups
have. This is expected to be a compile-time and `target`-directory size
win for almost all macOS Rust projects.
While breakage is possible it's possible to mitigate this with
project-local or global cargo configuration of the `dev` and `test` profiles.
[internals]: https://internals.rust-lang.org/t/help-test-faster-incremental-debug-macos-builds-on-nightly/14016/9
cargo-test-support wasn't using any of the caching or other logic from
Rustc, so this just swaps with a very basic implementation in order to
remove the dependency on `cargo`.
testsuite: Use split debuginfo on macos.
This switches the testsuite to use "unpacked" debuginfo on macos, which is a substantial performance boost. On my system, the testsuite runs 1.55 times faster with this change. Along with #9206, total testsuite time is 3.1 times faster.
Updates to edition handling.
This introduces some updates for edition handling (split into commits for review). In short:
* `cargo-features = ["edition2021"]` can be used to opt-in to 2021 support without needing to pass around `-Z unstable-options`. I tried to emphasize in the docs that this is only for testing and experimentation.
* Make `"2"` the default resolver for 2021 edition.
* Make `cargo fix --edition` mean the "next" edition from the present one, and support 2021. Also, if already at the latest edition, generate a warning instead an error.
* I decided to allow `cargo fix --edition` from 2018 to 2021 on the nightly channel without an explicit opt-in. It's tricky to implement with an opt-in (see comment in diff).
Partial for #9048.
Fixes#9047.
What was previously "Fixing" was a message for after the fixes had
been applied. I think it would be clearer if it said "Fixed",
to indicate that the fixes had actually finished.
The new "Fixing" is posted just before it starts. This is verbose-only
since it is a little noisy.
Add split-debuginfo profile option
This commit adds a new `split-debuginfo` option to Cargo compilation
profiles which gets forwarded to the `-Csplit-debuginfo` codegen option
in rustc. This commit also sets the default, only on macOS, to be
`-Csplit-debuginfo=unpacked`. The purpose of this change is to leverage
rust-lang/rust#79570 to avoid running `dsymutil` on incremental builds
while also preserving a pleasant debugging experience by default. This
should lead to much faster incremental build times on macOS since
`dsymutil` isn't exactly the speediest tool in the world.
This is technically a breaking change in Cargo because we're no longer
by-default producing the `*.dSYM` folders on macOS. If those are still
desired, however, authors can always run `dsymutil` themselves or
otherwise configure `split-debuginfo = 'packed'` in their
manifest/profile configuration.
This commit updates the rustc info cache to cache failures to execute
rustc as well as successes. This fixes a weird issue where if you're
probing for flags the `rustc_info_cache` test fails on channels which
don't have the flag since previously a failure to execute rustc resulted
in never caching the result.
This commit adds a new `split-debuginfo` option to Cargo compilation
profiles which gets forwarded to the `-Csplit-debuginfo` codegen option
in rustc. This commit also sets the default, only on macOS, to be
`-Csplit-debuginfo=unpacked`. The purpose of this change is to leverage
rust-lang/rust#79570 to avoid running `dsymutil` on incremental builds
while also preserving a pleasant debugging experience by default. This
should lead to much faster incremental build times on macOS since
`dsymutil` isn't exactly the speediest tool in the world.
This is technically a breaking change in Cargo because we're no longer
by-default producing the `*.dSYM` folders on macOS. If those are still
desired, however, authors can always run `dsymutil` themselves or
otherwise configure `split-debuginfo = 'packed'` in their
manifest/profile configuration.
Add contributor guide.
This consolidates and extends the contributor information in a single place. This is an mdbook project, along with a CI job which will build and deploy it to GitHub Pages at <https://rust-lang.github.io/cargo/contrib/>.
You can view a rendered version here: <https://ehuss.github.io/cargo/contrib/>
I don't know if this will actually be helpful to anyone, but I figured it's worth a shot.
NOTE: The CI deploy is designed to preserve the existing gh-pages content. However, it will **delete the history** on that branch. I think that should be fine, there doesn't seem to be too much interesting stuff there. I do have a backup in my fork, though. Some extra scrutiny on the code might be wise. The reason it deletes the history is because deploying mdbook on every push would balloon the repository size.
This commit updates Cargo's build of host dependencies to build them
with optimization level 0 by default instead of matching the profile of
the final binary.
Since Cargo's inception build dependencies have, by default, been built
in a profile that largely matches the profile of the final target
artifact. Build dependencies, however, rarely actually need to be
optimized and are often executing very small tasks, which means that
optimizing them often wastes a lot of build time. A great example of
this is procedural macros where `syn` and friends are pretty heavyweight
to optimize, and the amount of Rust code they're parsing is typically
quite small, so the time spent optimizing rarely comes as a benefit.
The goal of this PR is to improve build times on average in the
community by not spending time optimizing build dependencies (build
scripts, procedural macros, and their transitive dependencies). The PR
will not be a universal win for everyone, however. There's some
situations where your build time may actually increase:
* In some cases build scripts and procedural macros can take quite a
long time to run!
* Cargo may not build dependencies more than once if they're shared with
the main build. This only applies to builds without `--target` where
the same crate is used in the final binary as in a build script.
In these cases, however, the `build-override` profile has existed for
some time know and allows giving a knob to tweak this behavior. For
example to get back the previous build behavior of Cargo you would
specify, in `Cargo.toml`:
[profile.release.build-override]
opt-level = 3
or you can configure this via the environment:
export CARGO_PROFILE_RELEASE_BUILD_OVERRIDE_OPT_LEVEL=3
There are two notable features we would like to add in the future which
would make the impact of a change like this smaller, but they're not
implemented at this time (nor do we have concrete plans to implement
them). First we would like crates to have a way of specifying they
should be optimized by default, despite default profile options. Often
crates, like lalrpop historically, have abysmal performance in debug
mode and almost always (even in debug builds) want to be built in
release mode. The second feature is that ideally crate authors would be
able to tell Cargo to minimize the number of crates built, unifying
profiles where possible to avoid double-compiling crates.
At this time though the Cargo team feels that the benefit of changing
the defaults is well worth this change. Neither today nor directly after
this change will be a perfect world, but it's hoped that this change
makes things less bad!
reset lockfile information between resolutions
#8249 pointed out that some kind of lockfile data was leaking between calls to the resolver. @ehuss made a reproducing test case. This PR resets the `LockedMap` data structure when calling `register_previous_locks`.
lets see if CI likes it.
fix#8249
Use associated constants directly on primitive types instead of modules
This PR is in no way critical. It's more of a code cleanup. It comes as a result of me making https://github.com/rust-lang/rust/pull/70857 and search-and-replacing all usage of the soft-deprecated ways of reaching primitive type constants.
It makes the code slightly shorter, that's basically it. And showcases the recommended way of reaching these consts on new code :)
