Add support for wrapping cargo's rustc invocations by setting RUSTC_WRAPPER
To use sccache for cargo builds we need a simple way to get sccache into the rustc commandline when cargo invokes rustc. Currently this is only possible by hard-linking or copying the `sccache` binary to be named `rustc` and then either setting `RUSTC` to its path or putting it first in `$PATH`, both of which are sort of clunky and require manual steps even if installing sccache via `cargo install`.
This patch adds support for a `RUSTC_WRAPPER` environment variable which, if set, will simply be inserted as the actual binary for all rustc process execution, with rustc and all other rustc arguments following.
I didn't add any tests for this, I couldn't figure out the right place to put them, and presumably we'd need to build a helper binary of some sort to use as the wrapper. If you've got suggestions for how to do that properly I'd be happy to write tests.
This works well in my local testing:
```
luser@eye7:/build/read-process-memory$ /build/cargo/target/release/cargo clean; time RUSTC_WRAPPER=/build/sccache2/target/release/sccache RUSTC=/home/luser/.rustup/toolchains/beta-x86_64-unknown-linux-gnu/bin/rustc /build/cargo/target/release/cargo build
Compiling getopts v0.2.14
Compiling log v0.3.6
Compiling libc v0.2.16
Compiling rand v0.3.14
Compiling pulldown-cmark v0.0.3
Compiling tempdir v0.3.5
Compiling skeptic v0.5.0
Compiling read-process-memory v0.1.2-pre (file:///build/read-process-memory)
Finished dev [unoptimized + debuginfo] target(s) in 7.31 secs
real 0m7.733s
user 0m0.060s
sys 0m0.036s
luser@eye7:/build/read-process-memory$ /build/cargo/target/release/cargo clean; time RUSTC_WRAPPER=/build/sccache2/target/release/sccache RUSTC=/home/luser/.rustup/toolchains/beta-x86_64-unknown-linux-gnu/bin/rustc /build/cargo/target/release/cargo build
Compiling getopts v0.2.14
Compiling libc v0.2.16
Compiling log v0.3.6
Compiling pulldown-cmark v0.0.3
Compiling rand v0.3.14
Compiling tempdir v0.3.5
Compiling skeptic v0.5.0
Compiling read-process-memory v0.1.2-pre (file:///build/read-process-memory)
Finished dev [unoptimized + debuginfo] target(s) in 0.97 secs
real 0m1.049s
user 0m0.060s
sys 0m0.036s
```
The use of beta rustc is just to pick up the fix for making `--emit=dep-info` faster (which should ship in 1.17). If this patch ships in cargo then in the future developers should simply be able to `cargo install sccache; export RUSTC_WRAPPER=sccache` and `cargo build` as normal, but benefit from local sccache caching.
Better error message when a package version is not found
This changes the error message when a package *is* found but there's no
matching version to be a little more helpful.
Old: "no matching package named `<dep name>`"
New: "no matching version `<version>` found for package `<dep name>`"
Fixes#2997
Adjust submodule updating failure reporting
This PR changes output of cargo when updating a dependency fails because of it's submodules cannot be loaded. In my original example this was caused by submodule pointing to a revision which was deleted by force pushing. Fixes#3922.
Before:
```
$ cargo check
Updating git repository `<foo-url>`
error: failed to load source for a dependency on `foo`
Caused by:
Unable to update <foo-url>?rev=hash
To learn more, run the command again with --verbose.
```
After:
```
$ cargo check
Updating git repository `<foo-url>`
error: failed to load source for a dependency on `foo`
Caused by:
Unable to update <foo-url>?rev=hash
Caused by:
Failed to update submodule `submodule`
To learn more, run the command again with --verbose.
```
`--verbose` showing an additional `[9/-3] object not found - no match for id (hash)` has not been changed.
@alexcrichton since we have this nice timezone difference there was no chance of mentoring so far but any comments/suggestions are highly welcome. I'll likely check back on this next week.
This changes the error message when a package *is* found but there's no
matching version to be a little more helpful.
Old: "no matching package named `...`"
New: "no matching version `...` found for package `...`"
Now instead of reporting single generic "submodule update failed" a
dependency specific submodule update failed error message will be
reported and shown without --verbose.
Add note about Cargo.lock behavior with [replace]
The Cargo.lock behavior when using [replace] can be misleading if one
does not expect multiple versions of the crate to be included. This note
is intended to assure users that this behavior is expected, and it
suggests a way to verify their `[replace]` override is preferred.
I ran into this issue and ended up bugging @alexcrichton about it. Hopefully including this will reduce the support burden on cargo devs 😄.
The Cargo.lock behavior when using [replace] can be misleading if one
does not expect multiple versions of the crate to be included. This note
is intended to assure users that this behavior is expected, and it
suggests a way to verify their `[replace]` override is preferred.
Indicate that --lib is default for new, init.
I often forget for a moment which is the default behavior: `--bin` or `--lib`. This makes it clear in the usage text.
Fix rust-lang/rust 40955
Proposed fix for rust-lang/rust#40955.
I could also work on adding some additional tests, so we have all cases covered and automatically tested.
Looks like when vendor directories are checked into a VCS there's been instances
where deleting a folder in the VCS doesn't fully delete the folder from the
filesystem. This can lead to [spurious errors][moz] that are difficult to debug.
To help handle this tweak directory sources to ignore empty directories or
directories with only dotfiles by default.
[moz]: https://bugzilla.mozilla.org/show_bug.cgi?id=1342292
Add `[target.'cfg(...)']` syntax for rustc(doc)flags in .cargo/config
Allow to use the Rust `cfg(...)` syntax to configure rust(doc)flags.
The flags are concatenated when a build matches several `cfg`, or
several `cfg` and a $triple.
Fix#3499.
Allow to use the Rust `cfg(...)` syntax to configure rust(doc)flags.
The flags are concatenated when a build matches several `cfg`, or
several `cfg` and a $triple.
Fix#3499.
