Add an unstable --json=unused-externs flag to print unused externs
This adds an unstable flag to print a list of the extern names not used by cargo.
This PR will enable cargo to collect unused dependencies from all units and provide warnings.
The companion PR to cargo is: https://github.com/rust-lang/cargo/pull/8437
The goal is eventual stabilization of this flag in rustc as well as in cargo.
Discussion of this feature is mostly contained inside these threads: #57274#72342#72603
The feature builds upon the internal datastructures added by #72342
Externs are uniquely identified by name and the information is sufficient for cargo.
If the mode is enabled, rustc will print json messages like:
```
{"unused_extern_names":["byteorder","openssl","webpki"]}
```
For a crate that got passed byteorder, openssl and webpki dependencies but needed none of them.
### Q: Why not pass -Wunused-crate-dependencies?
A: See [ehuss's comment here](https://github.com/rust-lang/rust/issues/57274#issuecomment-624839355)
TLDR: it's cleaner. Rust's warning system wasn't built to be filtered or edited by cargo.
Even a basic implementation of the feature would have to change the "n warnings emitted" line that rustc prints at the end.
Cargo ideally wants to synthesize its own warnings anyways. For example, it would be hard for rustc to emit warnings like
"dependency foo is only used by dev targets", suggesting to make it a dev-dependency instead.
### Q: Make rustc emit used or unused externs?
A: Emitting used externs has the advantage that it simplifies cargo's collection job.
However, emitting unused externs creates less data to be communicated between rustc and cargo.
Often you want to paste a cargo command obtained from `cargo build -vv` for doing something
completely unrelated. The message is emitted always, even if no warning or error is emitted.
At that point, even this tiny difference in "noise" matters. That's why I went with emitting unused externs.
### Q: One json msg per extern or a collective json msg?
A: Same as above, the data format should be concise. Having 30 lines for the 30 crates a crate uses would be disturbing to readers.
Also it helps the cargo implementation to know that there aren't more unused deps coming.
### Q: Why use names of externs instead of e.g. paths?
A: Names are both sufficient as well as neccessary to uniquely identify a passed `--extern` arg.
Names are sufficient because you *must* pass a name when passing an `--extern` arg.
Passing a path is optional on the other hand so rustc might also figure out a crate's location from the file system.
You can also put multiple paths for the same extern name, via e.g. `--extern hello=/usr/lib/hello.rmeta --extern hello=/usr/local/lib/hello.rmeta`,
but rustc will only ever use one of those paths.
Also, paths don't identify a dependency uniquely as it is possible to have multiple different extern names point to the same path.
So paths are ill-suited for identification.
### Q: What about 2015 edition crates?
A: They are fully supported.
Even on the 2015 edition, an explicit `--extern` flag is is required to enable `extern crate foo;` to work (outside of sysroot crates, which this flag doesn't warn about anyways).
So the lint would still fire on 2015 edition crates if you haven't included a dependency specified in Cargo.toml using `extern crate foo;` or similar.
The lint won't fire if your sole use in the crate is through a `extern crate foo;` statement, but that's not its job.
For detecting unused `extern crate foo` statements, there is the `unused_extern_crates` lint
which can be enabled by `#![warn(unused_extern_crates)]` or similar.
cc ```@jsgf``` ```@ehuss``` ```@petrochenkov``` ```@estebank```
BTree: no longer search arrays twice to check Ord
A possible addition to / partial replacement of #83147: no longer linearly search the upper bound of a range in the initial portion of the keys we already know are below the lower bound.
- Should be faster: fewer key comparisons at the cost of some instructions dealing with offsets
- Makes code a little more complicated.
- No longer detects ill-defined `Ord` implementations, but that wasn't a publicised feature, and was quite incomplete, and was only done in the `range` and `range_mut` methods.
r? `@Mark-Simulacrum`
Make rust-demangler installable
Adds bootstrap rules to support installing rust-demangler, as an optional, in-tree `extended` tool. It can be included by updating `config.toml`, setting `extended = true`, and then either (a) adding `"rust-demangler"` to the `tools` array, or by enabling `profiler = true`. In other words, it is a _default_ `extended` tool if `profiler = true`.
When compiling with `-Z instrument-coverage`, the coverage reports are
generated by `llvm-cov`. `llvm-cov` includes a built-in demangler for
C++, and an option to supply an alternate demangler. For Rust, we have
`rust-demangler`, currently used in `rustc` coverage tests.
Fuchsia's toolchain for Rust is built via `./x.py install`. Fuchsia is
adding support for Rust coverage, and we need to include the
`rust-demangler` in the installed `bin` directory.
r? `@tmandry`
Adds bootstrap rules to support installing rust-demangler.
When compiling with `-Z instrument-coverage`, the coverage reports are
generated by `llvm-cov`. `llvm-cov` includes a built-in demangler for
C++, and an option to supply an alternate demangler. For Rust, we have
`rust-demangler`, currently used in `rustc` coverage tests.
Fuchsia's toolchain for Rust is built via `./x.py install`. Fuchsia is
adding support for Rust coverage, and we need to include the
`rust-demangler` in the installed `bin` directory.
Configured rust-demangler as an in-tree extended tool.
Added tests to support `./x.py test rust-demangler`.
Install with extended tools by default only if `profiler = true`.
Remove nightly features in rustc_type_ir
`rustc_type_ir` will be used as a type library by Chalk, which we want to be able to build on stable, so this PR removes the current nightly features used.
Document "standard" conventions for error messages
These are currently documented in the API guidelines:
https://rust-lang.github.io/api-guidelines/interoperability.html#error-types-are-meaningful-and-well-behaved-c-good-err
I think it makes sense to uplift this guideline (in a milder form) into
std docs. Printing and producing errors is something that even
non-expert users do frequently, so it is useful to give at least some
indication of what a typical error message looks like.
Add an Mmap wrapper to rustc_data_structures
This wrapper implements StableAddress and falls back to directly reading the file on wasm32.
Taken from #83640, which I will close due to the perf regression.
rustdoc: Don't load all extern crates unconditionally
Instead, only load the crates that are linked to with intra-doc links.
This doesn't help very much with any of rustdoc's fundamental issues
with freezing the resolver, but it at least fixes a stable-to-stable
regression, and makes the crate loading model somewhat more consistent
with rustc's. I tested and it unfortunately does not help at all with https://github.com/rust-lang/rust/pull/82496.
Closes https://github.com/rust-lang/rust/issues/68427. Let me know if you want me to open a separate issue for not freezing the resolver.
r? `@petrochenkov` cc `@eddyb` `@ollie27`
tidy: Add ignore-rules for the line length check
This is step 1 towards fixing https://github.com/rust-lang/rust/issues/77548.
This PR contains the `tidy` change from https://github.com/rust-lang/rust/pull/77675. The "ignoring file length unnecessarily" check is temporarily disabled to simplify landing the ignore-rules. This check will be re-enabled in a follow-up PR.
This is step 1 towards fixing #77548.
This commit includes the tidy change from #77675.
The "ignoring file length unnecessarily" check is temporarily
disabled to simplify landing the ignore-rules.
That check will be re-enabled in a follow-up PR.
Translate counters from Rust 1-based to LLVM 0-based counter ids
A colleague contacted me and asked why Rust's counters start at 1, when
Clangs appear to start at 0. There is a reason why Rust's internal
counters start at 1 (see the docs), and I tried to keep them consistent
when codegenned to LLVM's coverage mapping format. LLVM should be
tolerant of missing counters, but as my colleague pointed out,
`llvm-cov` will silently fail to generate a coverage report for a
function based on LLVM's assumption that the counters are 0-based.
See:
https://github.com/llvm/llvm-project/blob/main/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp#L170
Apparently, if, for example, a function has no branches, it would have
exactly 1 counter. `CounterValues.size()` would be 1, and (with the
1-based index), the counter ID would be 1. This would fail the check
and abort reporting coverage for the function.
It turns out that by correcting for this during coverage map generation,
by subtracting 1 from the Rust Counter ID (both when generating the
counter increment intrinsic call, and when adding counters to the map),
some uncovered functions (including in tests) now appear covered! This
corrects the coverage for a few tests!
r? `@tmandry`
FYI: `@wesleywiser`
Avoid sorting by DefId for `necessary_variants()`
Follow-up to https://github.com/rust-lang/rust/pull/83074. Originally I tried removing `impl Ord for DefId` but that hit *lots* of errors 😅 so I thought I would start with easy things.
I am not sure whether this could actually cause invalid query results, but this is used from `MarkSymbolVisitor::visit_arm` so it's at least feasible.
r? `@Aaron1011`
A colleague contacted me and asked why Rust's counters start at 1, when
Clangs appear to start at 0. There is a reason why Rust's internal
counters start at 1 (see the docs), and I tried to keep them consistent
when codegenned to LLVM's coverage mapping format. LLVM should be
tolerant of missing counters, but as my colleague pointed out,
`llvm-cov` will silently fail to generate a coverage report for a
function based on LLVM's assumption that the counters are 0-based.
See:
https://github.com/llvm/llvm-project/blob/main/llvm/lib/ProfileData/Coverage/CoverageMapping.cpp#L170
Apparently, if, for example, a function has no branches, it would have
exactly 1 counter. `CounterValues.size()` would be 1, and (with the
1-based index), the counter ID would be 1. This would fail the check
and abort reporting coverage for the function.
It turns out that by correcting for this during coverage map generation,
by subtracting 1 from the Rust Counter ID (both when generating the
counter increment intrinsic call, and when adding counters to the map),
some uncovered functions (including in tests) now appear covered! This
corrects the coverage for a few tests!
Maintain supported sanitizers as a target property
In an effort to remove a hard-coded allow-list for target-sanitizer support correspondence, this PR moves the configuration to the target options.
Perhaps the one notable change made in this PR is this doc-comment:
```rust
/// The sanitizers supported by this target
///
/// Note that the support here is at a codegen level. If the machine code with sanitizer
/// enabled can generated on this target, but the necessary supporting libraries are not
/// distributed with the target, the sanitizer should still appear in this list for the target.
```
Previously the target would typically be added to the allow-list at the same time as the supporting runtime libraries are shipped for the target. However whether we ship the runtime libraries or not needn't be baked into the compiler; and if we don't users will receive a significantly more directed error about library not being found.
Fixes#81802
This commit adds an additional target property – `supported_sanitizers`,
and replaces the hardcoded allowlists in argument parsing to use this
new property.
Fixes#81802
Instead, only load the crates that are linked to with intra-doc links.
This doesn't help very much with any of rustdoc's fundamental issues
with freezing the resolver, but it at least fixes a stable-to-stable
regression, and makes the crate loading model somewhat more consistent
with rustc's.
Fix stack overflow detection on FreeBSD 11.1+
Beginning with FreeBSD 10.4 and 11.1, there is one guard page by
default. And the stack autoresizes, so if Rust allocates its own guard
page, then FreeBSD's will simply move up one page. The best solution is
to just use the OS's guard page.
2229: Support migration via rustfix
- Adds support of machine applicable suggestions for `disjoint_capture_drop_reorder`.
- Doesn't migrate in the case of pre-existing bugs in user code
r? ``@nikomatsakis``
Simplify coverage tests
This change reduces the risk of impacting coverage tests on unrelated
changes (such as MIR and Span changes), and reduces the burden when
blessing coverage changes in case it is necessary.
* Remove all spanview tests. The spanview tests were useful during
development, but they can be generated as needed, via compiler command
line flags. They aren't critical to confirming coverage results. (The
coverage report tests are sufficient.)
When spanview regeneration was necessary, the diffs were way too hard
to read to be useful anyway. So I'm removing them to reduce friction
from a feature that is no longer useful.
* Remove the requirement for `llvm-cov show --debug` when blessing
tests. The `--debug` flag is, unfortunately, only available if LLVM is
built with `optimize = false` (in Rust's config.toml). This adds
significant time and resource burdens to the contributor's build. As
it turns out, for other reasons in the past, I wasn't actually using
the debug output (counter info) to validate coverage anymore either,
so it was required for no reason, I now realize.
Fix double-drop in `Vec::from_iter(vec.into_iter())` specialization when items drop during panic
This fixes the double-drop but it leaves a behavioral difference compared to the default implementation intact: In the default implementation the source and the destination vec are separate objects, so they get dropped separately. Here they share an allocation and the latter only exists as a pointer into the former. So if dropping the former panics then this fix will leak more items than the default implementation would. Is this acceptable or should the specialization also mimic the default implementation's drops-during-panic behavior?
Fixes#83618
`@rustbot` label T-libs-impl
rustdoc: Add unstable option to only emit shared/crate-specific files
The intended use case is for docs.rs, which can now copy exactly the
files it cares about, rather than having to guess based on whether they
have a resource suffix or not. In particular, some files have a resource
suffix but cannot be shared between crates: https://github.com/rust-lang/docs.rs/pull/1312#issuecomment-798783688
The end goal is to fixrust-lang/docs.rs#1327 by reverting rust-lang/docs.rs#1324.
This obsoletes `--print=unversioned-files`, which I plan to remove as
soon as docs.rs stops using it.
I recommend reviewing this one commit at a time.
r? ``@GuillaumeGomez`` cc ``@Nemo157`` ``@pietroalbini``
Rework `std::sys::windows::alloc`
I came across https://github.com/rust-lang/rust/pull/76676#discussion_r488729990, which points out that there was unsound code in the Windows alloc code, creating a &mut to possibly uninitialized memory. I reworked the code so that that particular issue does not occur anymore, and started adding more documentation and safety comments.
Full list of changes:
- moved and documented the relevant Windows Heap API functions
- refactor `allocate_with_flags` to `allocate` (and remove the other helper functions), which now takes just a `bool` if the memory should be zeroed
- add checks for if `GetProcessHeap` returned null
- add a test that checks if the size and alignment of a `Header` are indeed <= `MIN_ALIGN`
- add `#![deny(unsafe_op_in_unsafe_fn)]` and the necessary unsafe blocks with safety comments
I feel like I may have overdone the documenting, the unsoundness fix is the most important part; I could spit this PR up in separate parts.
