Simplify lazy DefPathHash decoding by using an on-disk hash table.
This PR simplifies the logic around mapping `DefPathHash` values encountered during incremental compilation to valid `DefId`s in the current session. It is able to do so by using an on-disk hash table encoding that allows for looking up values directly, i.e. without deserializing the entire table.
The main simplification comes from not having to keep track of `DefPathHashes` being used during the compilation session.
Use a separate interner type for UniqueTypeId
Using symbol::Interner makes it very easy to mixup UniqueTypeId symbols
with the global interner. In fact the Debug implementation of
UniqueTypeId did exactly this.
Using a separate interner type also avoids prefilling the interner with
unused symbols and allow for optimizing the symbol interner for parallel
access without negatively affecting the single threaded module codegen.
Using symbol::Interner makes it very easy to mixup UniqueTypeId symbols
with the global interner. In fact the Debug implementation of
UniqueTypeId did exactly this.
Using a separate interner type also avoids prefilling the interner with
unused symbols and allow for optimizing the symbol interner for parallel
access without negatively affecting the single threaded module codegen.
Split rustc_mir
The `rustc_mir` crate is the second largest in the compiler.
This PR splits it up into 5 crates:
- rustc_borrowck;
- rustc_const_eval;
- rustc_mir_dataflow;
- rustc_mir_transform;
- rustc_monomorphize.
Pin bootstrap checksums and add a tool to update it automatically
⚠️⚠️ This is just a proactive hardening we're performing on the build system, and it's not prompted by any known compromise. If you're aware of security issues being exploited please [check out our responsible disclosure page](https://www.rust-lang.org/policies/security). ⚠️⚠️
---
This PR aims to improve Rust's supply chain security by pinning the checksums of the bootstrap compiler downloaded by `x.py`, preventing a compromised `static.rust-lang.org` from affecting building the compiler. The checksums are stored in `src/stage0.json`, which replaces `src/stage0.txt`. This PR also adds a tool to automatically update the bootstrap compiler.
The changes in this PR were originally discussed in [Zulip](https://zulip-archive.rust-lang.org/stream/241545-t-release/topic/pinning.20stage0.20hashes.html).
## Potential attack
Before this PR, an attacker who wanted to compromise the bootstrap compiler would "just" need to:
1. Gain write access to `static.rust-lang.org`, either by compromising DNS or the underlying storage.
2. Upload compromised binaries and corresponding `.sha256` files to `static.rust-lang.org`.
There is no signature verification in `x.py` as we don't want the build system to depend on GPG. Also, since the checksums were not pinned inside the repository, they were downloaded from `static.rust-lang.org` too: this only protected from accidental changes in `static.rust-lang.org` that didn't change the `*.sha256` files. The attack would allow the attacker to compromise past and future invocations of `x.py`.
## Mitigations introduced in this PR
This PR adds pinned checksums for all the bootstrap components in `src/stage0.json` instead of downloading the checksums from `static.rust-lang.org`. This changes the attack scenario to:
1. Gain write access to `static.rust-lang.org`, either by compromising DNS or the underlying storage.
2. Upload compromised binaries to `static.rust-lang.org`.
3. Land a (reviewed) change in the `rust-lang/rust` repository changing the pinned hashes.
Even with a successful attack, existing clones of the Rust repository won't be affected, and once the attack is detected reverting the pinned hashes changes should be enough to be protected from the attack. This also enables further mitigations to be implemented in following PRs, such as verifying signatures when pinning new checksums (removing the trust on first use aspect of this PR) and adding a check in CI making sure a PR updating the checksum has not been tampered with (see the future improvements section).
## Additional changes
There are additional changes implemented in this PR to enable the mitigation:
* The `src/stage0.txt` file has been replaced with `src/stage0.json`. The reasoning for the change is that there is existing tooling to read and manipulate JSON files compared to the custom format we were using before, and the slight challenge of manually editing JSON files (no comments, no trailing commas) are not a problem thanks to the new `bump-stage0`.
* A new tool has been added to the repository, `bump-stage0`. When invoked, the tool automatically calculates which release should be used as the bootstrap compiler given the current version and channel, gathers all the relevant checksums and updates `src/stage0.json`. The tool can be invoked by running:
```
./x.py run src/tools/bump-stage0
```
* Support for downloading releases from `https://dev-static.rust-lang.org` has been removed, as it's not possible to verify checksums there (it's customary to replace existing artifacts there if a rebuild is warranted). This will require a change to the release process to avoid bumping the bootstrap compiler on beta before the stable release.
## Future improvements
* Add signature verification as part of `bump-stage0`, which would require the attacker to also obtain the release signing keys in order to successfully compromise the bootstrap compiler. This would be fine to add now, as the burden of installing the tool to verify signatures would only be placed on whoever updates the bootstrap compiler, instead of everyone compiling Rust.
* Add a check on CI that ensures the checksums in `src/stage0.json` are the expected ones. If a PR changes the stage0 file CI should also run the `bump-stage0` tool and fail if the output in CI doesn't match the committed file. This prevents the PR author from tweaking the output of the tool manually, which would otherwise be close to impossible for a human to detect.
* Automate creating the PRs bumping the bootstrap compiler, by setting up a scheduled job in GitHub Actions that runs the tool and opens a PR.
* Investigate whether a similar mitigation can be done for "download from CI" components like the prebuilt LLVM.
r? `@Mark-Simulacrum`
Warn when [T; N].into_iter() is ambiguous in the new edition.
Fixes https://github.com/rust-lang/rust/issues/88475
In https://github.com/rust-lang/rust/issues/88475, a situation was found where `[T; N].into_iter()` becomes *ambiguous* in the new edition. This is different than the case where `(&[T; N]).into_iter()` resolves differently, which was the only case handled by the `array_into_iter` lint. This is almost identical to the new-traits-in-the-prelude problem. Effectively, due to the array-into-iter hack disappearing in Rust 2021, we effectively added `IntoIterator` to the 'prelude' in Rust 2021 specifically for arrays.
This modifies the prelude collisions lint to detect that case and emit a `array_into_iter` lint in that case.
Instead of updating global state to mark attributes as used,
we now explicitly emit a warning when an attribute is used in
an unsupported position. As a side effect, we are to emit more
detailed warning messages (instead of just a generic "unused" message).
`Session.check_name` is removed, since its only purpose was to mark
the attribute as used. All of the callers are modified to use
`Attribute.has_name`
Additionally, `AttributeType::AssumedUsed` is removed - an 'assumed
used' attribute is implemented by simply not performing any checks
in `CheckAttrVisitor` for a particular attribute.
We no longer emit unused attribute warnings for the `#[rustc_dummy]`
attribute - it's an internal attribute used for tests, so it doesn't
mark sense to treat it as 'unused'.
With this commit, a large source of global untracked state is removed.
Update the backtrace crate in libstd
This commit updates the backtrace crate in libstd now that dependencies
have been updated to use `memchr` from the standard library as well.
This is mostly just making sure deps are up-to-date and have all the
latest-and-greatest fixes and such.
Closesrust-lang/backtrace-rs#432
This commit updates the backtrace crate in libstd now that dependencies
have been updated to use `memchr` from the standard library as well.
This is mostly just making sure deps are up-to-date and have all the
latest-and-greatest fixes and such.
Closesrust-lang/backtrace-rs#432
Unbox mutexes, condvars and rwlocks on hermit
[RustyHermit](https://github.com/hermitcore/rusty-hermit) provides now movable synchronization primitives and we are able to unbox mutexes and condvars.
Matthew's work on improving NLL's "higher-ranked subtype error"s
This PR rebases `@matthewjasper's` [branch](https://github.com/matthewjasper/rust/tree/nll-hrtb-errors) which has great work to fix the obscure higher-ranked subtype errors that are tracked in #57374.
These are a blocker to turning full NLLs on, and doing some internal cleanups to remove some of the old region code.
The goal is so `@nikomatsakis` can take a look at this early, and I'll then do my best to help do the changes and followup work to land this work, and move closer to turning off the migration mode.
I've only updated the branch and made it compile, removed a warning or two.
r? `@nikomatsakis`
(Here's the [zulip topic to discuss this](https://rust-lang.zulipchat.com/#narrow/stream/122657-t-compiler.2Fwg-nll/topic/.2357374.3A.20improving.20higher-ranked.20subtype.20errors.20via.20.2386700) that Niko wanted)
Update cargo
8 commits in b51439fd8b505d4800a257acfecf3c69f81e35cf..e96bdb0c3d0a418e7fcd7fbd69be08abf830b4bc
2021-08-09 18:40:05 +0000 to 2021-08-17 22:58:47 +0000
- Support using rustbot to ping the Windows group (rust-lang/cargo#9802)
- Show information about abnormal `fix` errors. (rust-lang/cargo#9799)
- Bump jobserver. (rust-lang/cargo#9798)
- Render build-std web links as hyperlinks (rust-lang/cargo#9795)
- Teach cargo to failfast on recursive/corecursive aliases (rust-lang/cargo#9791)
- Fix value-after-table error with profiles. (rust-lang/cargo#9789)
- Fix plugin registrar change. (rust-lang/cargo#9790)
- Ability to specify the output name for a bin target different from the crate name (rust-lang/cargo#9627)
Update `polonius-engine` to 0.13.0
This PR updates the use of `polonius-engine` to the recently released 0.13.0:
- this version renamed a lot of relations to match the current terminology
- "illegal subset relationships errors" (AKA "subset errors" or "universal region errors" in rustc parlance) have been implemented in all variants, and therefore the `Hybrid` variant can be the rustc default once again
- some of the blessed expectations were updated: new tests have been added since the last time I updated the tests, diagnostics have changed, etc.
In particular:
- a few tests had trivial expectations changes such as basic diagnostics changes for the migrate-mode and full NLLs
- others were recursion and lengths limits which emits a file, and under the polonius compare-mode, the folder has a different name
- a few tests were ignored in the NLL compare-mode for reasons that obviously also apply to Polonius
- some diagnostics were unified so that older expectations no longer made sense: the NLL and Polonius outputs were identical.
- in a few cases Polonius gets a chance to emit more errors than NLLs
A few tests in the compare-mode still are super slow and trigger the 60s warning, or OOM rustc during fact generation, and I've detailed these [on Zulip](https://rust-lang.zulipchat.com/#narrow/stream/186049-t-compiler.2Fwg-polonius/topic/Challenges.20for.20move.2Finit.2C.20liveness.2C.20and.20.60Location.3A.3AAll.60):
- `src/test/ui/numbers-arithmetic/saturating-float-casts.rs` -> OOM during rustc fact generation
- `src/test/ui/numbers-arithmetic/num-wrapping.rs`
- `src/test/ui/issues/issue-72933-match-stack-overflow.rs`
- `src/test/ui/issues/issue-74564-if-expr-stack-overflow.rs`
- `src/test/ui/repr/repr-no-niche.rs`
In addition, 2 tests don't currently pass and I didn't want to bless them now: they deal with HRTBs and miss errors that NLLs emit. We're currently trying to see if we need chalk to deal with HRTB errors (as we thought we would have to) but during the recent sprint, we discovered that we may be able to detect some of these errors in a way that resembles subset errors:
- `ui/hrtb/hrtb-just-for-static.rs` -> 3 errors in NLL, 2 in polonius: a missing error about HRTB + needing to outlive 'static
- `ui/issues/issue-26217.rs` -> missing HRTB that makes the test compile instead of emitting an error
We'll keep talking about this at the next sprint as well.
cc `@rust-lang/wg-polonius` r? `@nikomatsakis`
Improve non_fmt_panics suggestion based on trait impls.
This improves the non_fmt_panics lint suggestions by checking first which trait (Display or Debug) are actually implemented on the type.
Fixes https://github.com/rust-lang/rust/issues/87313
Fixes https://github.com/rust-lang/rust/issues/87999
Before:
```
help: add a "{}" format string to Display the message
|
2 | panic!("{}", Some(1));
| +++++
help: or use std::panic::panic_any instead
|
2 | std::panic::panic_any(Some(1));
| ~~~~~~~~~~~~~~~~~~~~~
```
After:
```
help: add a "{:?}" format string to use the Debug implementation of `Option<i32>`
|
2 | panic!("{:?}", Some(1));
| +++++++
help: or use std::panic::panic_any instead
|
2 | std::panic::panic_any(Some(1));
| ~~~~~~~~~~~~~~~~~~~~~
```
r? `@estebank`
Uplift the invalid_atomic_ordering lint from clippy to rustc
This is mostly just a rebase of https://github.com/rust-lang/rust/pull/79654; I've copy/pasted the text from that PR below.
r? `@lcnr` since you reviewed the last one, but feel free to reassign.
---
This is an implementation of https://github.com/rust-lang/compiler-team/issues/390.
As mentioned, in general this turns an unconditional runtime panic into a (compile time) lint failure. It has no false positives, and the only false negatives I'm aware of are if `Ordering` isn't specified directly and is comes from an argument/constant/whatever.
As a result of it having no false positives, and the alternative always being strictly wrong, it's on as deny by default. This seems right.
In the [zulip stream](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Uplift.20the.20.60invalid_atomic_ordering.60.20lint.20from.20clippy/near/218483957) `@joshtriplett` suggested that lang team should FCP this before landing it. Perhaps libs team cares too?
---
Some notes on the code for reviewers / others below
## Changes from clippy
The code is changed from [the implementation in clippy](68cf94f6a6/clippy_lints/src/atomic_ordering.rs) in the following ways:
1. Uses `Symbols` and `rustc_diagnostic_item`s instead of string literals.
- It's possible I should have just invoked Symbol::intern for some of these instead? Seems better to use symbol, but it did require adding several.
2. The functions are moved to static methods inside the lint struct, as a way to namespace them.
- There's a lot of other code in that file — which I picked as the location for this lint because `@jyn514` told me that seemed reasonable.
3. Supports unstable AtomicU128/AtomicI128.
- I did this because it was almost easier to support them than not — not supporting them would have (ideally) required finding a way not to give them a `rustc_diagnostic_item`, which would have complicated an already big macro.
- These don't have tests since I wasn't sure if/how I should make tests conditional on whether or not the target has the atomic... This is to a certain extent an issue of 64bit atomics too, but 128-bit atomics are much less common. Regardless, the existing tests should be *more* than thorough enough here.
4. Minor changes like:
- grammar tweaks ("loads cannot have `Release` **and** `AcqRel` ordering" => "loads cannot have `Release` **or** `AcqRel` ordering")
- function renames (`match_ordering_def_path` => `matches_ordering_def_path`),
- avoiding clippy-specific helper methods that don't exist in rustc_lint and didn't seem worth adding for this case (for example `cx.struct_span_lint` vs clippy's `span_lint_and_help` helper).
## Potential issues
(This is just about the code in this PR, not conceptual issues with the lint or anything)
1. I'm not sure if I should have used a diagnostic item for `Ordering` and its variants (I couldn't figure out how really, so if I should do this some pointers would be appreciated).
- It seems possible that failing to do this might possibly mean there are more cases this lint would miss, but I don't really know how `match_def_path` works and if it has any pitfalls like that, so maybe not.
2. I *think* I deprecated the lint in clippy (CC `@flip1995` who asked to be notified about clippy changes in the future in [this comment](https://github.com/rust-lang/rust/pull/75671#issuecomment-718731659)) but I'm not sure if I need to do anything else there.
- I'm kind of hoping CI will catch if I missed anything, since `x.py test src/tools/clippy` fails with a lot of errors with and without my changes (and is probably a nonsense command regardless). Running `cargo test` from src/tools/clippy also fails with unrelated errors that seem like refactorings that didnt update clippy? So, honestly no clue.
3. I wasn't sure if the description/example I gave good. Hopefully it is. The example is less thorough than the one from clippy here: https://rust-lang.github.io/rust-clippy/master/index.html#invalid_atomic_ordering. Let me know if/how I should change it if it needs changing.
4. It pulls in the `if_chain` crate. This crate was already used in clippy, and seems like it's used elsewhere in rustc, but I'm willing to rewrite it to not use this if needed (I'd prefer not to, all things being equal).
- Deprecate clippy::invalid_atomic_ordering
- Use rustc_diagnostic_item for the orderings in the invalid_atomic_ordering lint
- Reduce code duplication
- Give up on making enum variants diagnostic items and just look for
`Ordering` instead
I ran into tons of trouble with this because apparently the change to
store HIR attrs in a side table also gave the DefIds of the
constructor instead of the variant itself. So I had to change
`matches_ordering` to also check the grandparent of the defid as well.
- Rename `atomic_ordering_x` symbols to just the name of the variant
- Fix typos in checks - there were a few places that said "may not be
Release" in the diagnostic but actually checked for SeqCst in the lint.
- Make constant items const
- Use fewer diagnostic items
- Only look at arguments after making sure the method matches
This prevents an ICE when there aren't enough arguments.
- Ignore trait methods
- Only check Ctors instead of going through `qpath_res`
The functions take values, so this couldn't ever be anything else.
- Add if_chain to allowed dependencies
- Fix grammar
- Remove unnecessary allow
