Update `unexpected_cfgs` lint for Cargo new `check-cfg` config
This PR updates the diagnostics output of the `unexpected_cfgs` lint for Cargo new `check-cfg` config.
It's a simple and cost-less alternative to the build-script `cargo::rustc-check-cfg` instruction.
```toml
[lints.rust]
unexpected_cfgs = { level = "warn", check-cfg = ['cfg(foo, values("bar"))'] }
```
This PR also adds a Cargo specific section regarding check-cfg and Cargo inside rustc's book (motivation is described inside the file, but mainly check-cfg is a rustc feature not a Cargo one, Cargo only enabled the feature, it does not own it; T-cargo even considers the `check-cfg` lint config to be an implementation detail).
This PR also updates the links to refer to that sub-page when using Cargo from rustc.
As well as updating the lint doc to refer to the check-cfg docs.
~**Not to be merged before https://github.com/rust-lang/cargo/pull/13913 reaches master!**~ (EDIT: merged in https://github.com/rust-lang/rust/pull/125237)
`@rustbot` label +F-check-cfg
r? `@fmease` *(feel free to roll)*
Fixes https://github.com/rust-lang/rust/issues/124800
cc `@epage` `@weihanglo`
coverage: Memoize and simplify counter expressions
When creating coverage counter expressions as part of coverage instrumentation, we often end up creating obviously-redundant expressions like `c1 + (c0 - c1)`, which is equivalent to just `c0`.
To avoid doing so, this PR checks when we would create an expression matching one of 5 patterns, and uses the simplified form instead:
- `(a - b) + b` → `a`.
- `(a + b) - b` → `a`.
- `(a + b) - a` → `b`.
- `a + (b - a)` → `b`.
- `a - (a - b)` → `b`.
Of all the different ways to combine 3 operands and 2 operators, these are the patterns that allow simplification.
(Some of those patterns currently don't occur in practice, but are included anyway for completeness, to avoid having to add them later as branch coverage and MC/DC coverage support expands.)
---
This PR also adds memoization for newly-created (or newly-simplified) counter expressions, to avoid creating duplicates.
This currently makes no difference to the final mappings, but is expected to be useful for MC/DC coverage of match expressions, as proposed by https://github.com/rust-lang/rust/pull/124278#issuecomment-2106754753.
Suggest setting lifetime in borrowck error involving types with elided lifetimes
```
error: lifetime may not live long enough
--> $DIR/ex3-both-anon-regions-both-are-structs-2.rs:7:5
|
LL | fn foo(mut x: Ref, y: Ref) {
| ----- - has type `Ref<'_, '1>`
| |
| has type `Ref<'_, '2>`
LL | x.b = y.b;
| ^^^^^^^^^ assignment requires that `'1` must outlive `'2`
|
help: consider introducing a named lifetime parameter
|
LL | fn foo<'a>(mut x: Ref<'a, 'a>, y: Ref<'a, 'a>) {
| ++++ ++++++++ ++++++++
```
As can be seen above, it currently doesn't try to compare the `ty::Ty` lifetimes that diverged vs the `hir::Ty` to correctly suggest the following
```
help: consider introducing a named lifetime parameter
|
LL | fn foo<'a>(mut x: Ref<'_, 'a>, y: Ref<'_, 'a>) {
| ++++ ++++++++ ++++++++
```
but I believe this to still be an improvement over the status quo.
Fix#40990.
Remove unnecessary -fembed-bitcode usage now that it's deprecated
This is a partial revert of 6d819a4b8f because https://github.com/rust-lang/cc-rs/pull/812 removed this flag entirely, meaning we shouldn't have to pass this manually anymore
This replaces the hardcoded rustc-perf commit and ad-hoc downloading and
unpacking of its zipped source with defaulting to use the new rustc-perf
submodule.
While it would be nice to make `opt-dist` able to initialize the
submodule automatically when pointing to a Rust checkout _other_ than
the one opt-dist was built in, that would require a bigger refactor that
moved `update_submodule`, from bootstrap, into build_helper.
Regardless, I imagine it must be quite rare to use `opt-dist` with a
checkout that is neither from a rust-src tarball (which will contain the
submodule), nor the checkout opt-dist itself was built (bootstrap will
update the submodule when opt-dist is built).
This avoids having normal builds pay the cost of initializing that
submodule, while still ensuring it's available whenever `opt-dist` is
built.
Note that, at this point, `opt-dist` will not yet use the submodule,
that will be handled in a subsequent commit.
Currently, it's very challenging to perform a sandboxed `opt-dist`
bootstrap because the tool requires `rustc-perf` to be present, but
there is no proper management/tracking of it. Instead, a specific commit
is hardcoded where it is needed, and a non-checksummed zip is fetched
ad-hoc. This happens in two places:
`src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile`:
```dockerfile
ENV PERF_COMMIT 4f313add609f43e928e98132358e8426ed3969ae
RUN curl -LS -o perf.zip https://ci-mirrors.rust-lang.org/rustc/rustc-perf-$PERF_COMMIT.zip && \
unzip perf.zip && \
mv rustc-perf-$PERF_COMMIT rustc-perf && \
rm perf.zip
```
`src/tools/opt-dist/src/main.rs`
```rust
// FIXME: add some mechanism for synchronization of this commit SHA with
// Linux (which builds rustc-perf in a Dockerfile)
// rustc-perf version from 2023-10-22
const PERF_COMMIT: &str = "4f313add609f43e928e98132358e8426ed3969ae";
let url = format!("https://ci-mirrors.rust-lang.org/rustc/rustc-perf-{PERF_COMMIT}.zip");
let client = reqwest::blocking::Client::builder()
.timeout(Duration::from_secs(60 * 2))
.connect_timeout(Duration::from_secs(60 * 2))
.build()?;
let response = retry_action(
|| Ok(client.get(&url).send()?.error_for_status()?.bytes()?.to_vec()),
"Download rustc-perf archive",
5,
)?;
```
This causes a few issues:
1. Maintainers need to be careful to bump PERF_COMMIT in both places
every time
2. In order to run `opt-dist` in a sandbox, you need to provide your own
`rustc-perf` (https://github.com/rust-lang/rust/pull/125125), but to
figure out which commit to provide you need to grep the Dockerfile
3. Even if you manage to provide the correct `rustc-perf`, its
dependencies are not included in the `vendor/` dir created during
`dist`, so it will fail to build from the published source tarballs
4. It is hard to provide any level of automation around updating the
`rustc-perf` in use, leading to staleness
Fundamentally, this means `rustc-src` tarballs no longer contain
everything you need to bootstrap Rust, and packagers hoping to leverage
`opt-dist` need to go out of their way to keep track of this "hidden"
dependency on `rustc-perf`.
This change adds rustc-perf as a git submodule, pinned to the current
`PERF_COMMIT` 4f313add609f43e928e98132358e8426ed3969ae. Subsequent
commits ensure the submodule is initialized when necessary, and make use
of it in `opt-dist`.
Fix `tests/debuginfo/strings-and-strs`.
It fails on my machine because it embeds pointer addresses in the expected output.
This commit replaces the addresses with `0x[...]`.
r? ```@Mark-Simulacrum```
Make `EvalCtxt` generic over `InferCtxtLike`
...but don't change any of the impls, yet! These can get uplifted as we add more methods to `InferCtxtLike`/`Interner` :3
This is built on top of #125230.
r? lcnr
