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 :)
Add windows-gnu CI and fix tests
One remaining failure:
```
---- features::feature_off_dylib stdout ----
running `d:\a\1\s\target\debug\cargo.exe build --features f1`
running `d:\a\1\s\target\debug\cargo.exe run -p bar`
thread 'features::feature_off_dylib' panicked at '
Expected: execs
but: exited with exit code: 101
--- stdout
--- stderr
Compiling foo v0.0.1 (D:\a\1\s\target\cit\t663\foo)
Compiling bar v0.0.1 (D:\a\1\s\target\cit\t663\foo\bar)
Finished dev [unoptimized + debuginfo] target(s) in 0.69s
Running `target\debug\bar.exe`
thread 'main' panicked at 'assertion failed: `(left == right)`
left: `"f1"`,
right: `"no f1"`', bar\src\main.rs:5:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: process didn't exit successfully: `target\debug\bar.exe` (exit code: 101)
', crates\cargo-test-support\src\lib.rs:833:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
failures:
features::feature_off_dylib
```
I disassembled the dylibs and `cargo run -p bar` correctly rebuilt it inside `target/debug/deps/` but did not copy it to `target/debug`. To further confirm, calling `cp target/debug/deps/foo.dll target/debug/` manually solved the issue.
Any idea?
----
I left `FIXME` in places where import lib should be added with https://github.com/rust-lang/cargo/pull/6875.
`TOOLCHAIN: nightly-x86_64-pc-windows-gnu` can be replaced with beta on Thursday.
This commit is the Cargo half of support necessary for
rust-lang/rust#70458. Today the compiler emits embedded bytecode in
rlibs by default, but compresses it. This is both extraneous disk space
and wasted build time for almost all builds, so the PR in question there
is changing rustc to have a `-Cembed-bitcode` flag which, when enabled,
places the bitcode in the object file rather than an auxiliary file (no
extra compression), but also enables `-Cembed-bitcode=no` to disable
bitcode emission entirely.
This Cargo support changes Cargo to pass `-Cembed-bitcode=no` for almost
all compilations. Cargo will keep `lto = true` and such working by not
passing this flag (and thus allowing bitcode to get embedded), but by
default `cargo build` and `cargo build --release` will no longer have
any bitcode in rlibs which should result in speedier builds!
Most of the changes here were around the test suite and various
assertions about the `rustc` command lines we spit out. One test was
hard-disabled until we can get `-Cembed-bitcode=no` into nightly, and
then we can make it a nightly-only test. The test will then be stable
again once `-Cembed-bitcode=no` hits stable.
Note that this is intended to land before the upstream `-Cembed-bitcode`
change. The thinking is that we'll land everything in rust-lang/rust all
at once so there's no build time regressions for anyone. If we were to
land the `-Cembed-bitcode` PR first then there would be a build time
regression until we land Cargo changes because rustc would be emitting
uncompressed bitcode by default and Cargo wouldn't be turning it off.
Re-implement proc-macro feature decoupling.
This is essentially a rewrite of #8003. Instead of adding proc-macro to the index, it uses a strategy of downloading all packages before doing feature resolution. Then the package can be inspected for the proc-macro field.
This is a fairly major change. A brief overview:
- `PackageSet` now has a `download_accessible` method which tries to download a minimal set of every accessible package. This isn't very smart right now, and errs on downloading too much. In most cases it should be the same (or nearly the same) as before. It downloads extra in the following cases:
- The check for `[target]` dependencies checks both host and target for every dependency. I could tighten that up a little so build dependencies only check for the host, but it would add some complexity and I wanted to get feedback first.
- Optional dependencies disabled by the new feature resolver will get downloaded.
- Removed the loop in computing unit dependencies where downloading used to reside.
- When downloading starts, it should now show a more accurate count of how many crates are to be downloaded. Previously the count would fluctuate while the graph is being built.
Add proc-macro to index, and new feature resolver.
This adds the "pm" field to the index so that Cargo can detect which packages contain a proc-macro without downloading the package.
The second commit builds on that to support proc-macros in the new "de-unification" of the new feature resolver. This prevents dependencies shared between proc-macros and other dependency kinds from having features unified.
cc #7915
