Rollup of 17 pull requests
Successful merges:
- #78455 (Introduce {Ref, RefMut}::try_map for optional projections in RefCell)
- #80144 (Remove giant badge in README)
- #80614 (Explain why borrows can't be held across yield point in async blocks)
- #80670 (TrustedRandomAaccess specialization composes incorrectly for nested iter::Zips)
- #80681 (Clarify what the effects of a 'logic error' are)
- #80764 (Re-stabilize Weak::as_ptr and friends for unsized T)
- #80901 (Make `x.py --color always` apply to logging too)
- #80902 (Add a regression test for #76281)
- #80941 (Do not suggest invalid code in pattern with loop)
- #80968 (Stabilize the poll_map feature)
- #80971 (Put all feature gate tests under `feature-gates/`)
- #81021 (Remove doctree::Import)
- #81040 (doctest: Reset errors before dropping the parse session)
- #81060 (Add a regression test for #50041)
- #81065 (codegen_cranelift: Fix redundant semicolon warn)
- #81069 (Add sample code for Rc::new_cyclic)
- #81081 (Add test for #34792)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
This copies the unknown_lints code clippy uses for its
unknown_clippy_lints lint to rustc. The unknown_clippy_lints code is
more advanced, because it doesn't suggest renamed or removed lints and
correctly suggest lower casing lints.
implement ptr::write without dedicated intrinsic
This makes `ptr::write` more consistent with `ptr::write_unaligned`, `ptr::read`, `ptr::read_unaligned`, all of which are implemented in terms of `copy_nonoverlapping`.
This means we can also remove `move_val_init` implementations in codegen and Miri, and its special handling in the borrow checker.
Also see [this Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/ptr.3A.3Aread.20vs.20ptr.3A.3Awrite).
It's not an internal lint:
- It's not in the rustc::internal lint group
- It's on unconditionally, because it actually lints `staged_api`, not
the compiler
This fixes a bug where `#[deny(rustc::internal)]` would warn that
`rustc::internal` was an unknown lint.
Remove DepKind::CrateMetadata and pre-allocation of DepNodes
Remove much of the special-case handling around crate metadata
dependency tracking by replacing `DepKind::CrateMetadata` and the
pre-allocation of corresponding `DepNodes` with on-demand invocation
of the `crate_hash` query.
Previously, clippy (and any other tool emitting lints) had to have their
own separate UNKNOWN_LINTS pass, because the compiler assumed any tool
lint could be valid. Now, as long as any lint starting with the tool
prefix exists, the compiler will warn when an unknown lint is present.
Don't try to add nested predicate to Rustdoc auto-trait `ParamEnv`
Fixes#80233
We already have logic in `evaluate_predicates` that tries to add
unimplemented predicates to our `ParamEnv`. Trying to add a predicate
that already holds can lead to errors later on, since projection
will prefer trait candidates from the `ParamEnv` to predicates from an
impl.
Set tokens on AST node in `collect_tokens`
A new `HasTokens` trait is introduced, which is used to move logic from
the callers of `collect_tokens` into the body of `collect_tokens`.
In addition to reducing duplication, this paves the way for PR #80689,
which needs to perform additional logic during token collection.
Use better ICE message when no MIR is available
The ICE message is somewhat confusing and overly specific - the issue is
that there's no MIR available.
This should make debugging these ICEs easier since the error tells you
what's actually wrong, not what it was trying to do when it failed.
cc https://github.com/rust-lang/rust/pull/80952#issuecomment-759198841
cc `````@jyn514`````
Update tests of "unused_lifetimes" lint for async functions and corresponding source code
Before this PR the following code would cause an error:
```
#![deny(unused_lifetimes)]
async fn f<'a>(_: &'a i32) {}
fn main() {}
```
It was happening because of the desugaring of return type in async functions. As a result of the desugaring, the return type contains all lifetimes involved in the function signature. And these lifetimes were interpreted separately from the same in the function scope => so they are unused.
Now, all lifetimes from the return type are interpreted as used. It is also not perfect, but at least this lint doesn't cause wrong errors now.
This PR connected to issues #78522, #77217
A new `HasTokens` trait is introduced, which is used to move logic from
the callers of `collect_tokens` into the body of `collect_tokens`.
In addition to reducing duplication, this paves the way for PR #80689,
which needs to perform additional logic during token collection.
Properly handle `SyntaxContext` of dummy spans in incr comp
Fixes#80336
Due to macro expansion, we may end up with spans with an invalid
location and non-root `SyntaxContext`. This commits preserves the
`SyntaxContext` of such spans in the incremental cache, and ensures
that we always hash the `SyntaxContext` when computing the `Fingerprint`
of a `Span`
Previously, we would discard the `SyntaxContext` during serialization to
the incremental cache, causing the span's `Fingerprint` to change across
compilation sessions.
Rework diagnostics for wrong number of generic args (fixes#66228 and #71924)
This PR reworks the `wrong number of {} arguments` message, so that it provides more details and contextual hints.
Fixes#80336
Due to macro expansion, we may end up with spans with an invalid
location and non-root `SyntaxContext`. This commits preserves the
`SyntaxContext` of such spans in the incremental cache, and ensures
that we always hash the `SyntaxContext` when computing the `Fingerprint`
of a `Span`
Previously, we would discard the `SyntaxContext` during serialization to
the incremental cache, causing the span's `Fingerprint` to change across
compilation sessions.
Consistently avoid constructing optimized MIR when not doing codegen
The optimized MIR for closures is being encoded unconditionally, while
being unnecessary for cargo check. This turns out to be especially
costly with MIR inlining enabled, since it triggers computation of
optimized MIR for all callees that are being examined for inlining
purposes https://github.com/rust-lang/rust/pull/77307#issuecomment-751915450.
Skip encoding of optimized MIR for closures, enum constructors, struct
constructors, and trait fns when not doing codegen, like it is already
done for other items since 49433.
The ICE message is somewhat confusing and overly specific - the issue is
that there's no MIR available.
This should make debugging these ICEs easier since the error tells you
what's actually wrong, not what it was trying to do when it failed.
cc https://github.com/rust-lang/rust/pull/80952#issuecomment-759198841
For example, this code:
struct S(i32, f32);
let S(x) = S(0, 1.0);
will make the compiler suggest either:
let S(x, _) = S(0, 1.0);
or:
let S(x, ..) = S(0, 1.0);
Fix --pretty=expanded with --remap-path-prefix
Per https://github.com/rust-lang/rust/issues/80832, using
--pretty=expanded and --remap-path-prefix results in an ICE.
This is becasue the session source files table is stored in remapped
form, whereas --pretty-expanded looks up unremapped files. This remaps
the path prefixes before lookup.
~~There don't appear to be any existing tests for --pretty=expanded; I'll look into
adding some.~~ Never mind, found the pretty tests.
Fixes#80832
Added support for i386-unknown-linux-gnu and i486-unknown-linux-gnu
Support for both can be useful when creating new firmware, boot loaders,
or embedded operating systems.
Separate out a `hir::Impl` struct
This makes it possible to pass the `Impl` directly to functions, instead
of having to pass each of the many fields one at a time. It also
simplifies matches in many cases.
See `rustc_save_analysis::dump_visitor::process_impl` or `rustdoc::clean::clean_impl` for a good example of how this makes `impl`s easier to work with.
r? `@petrochenkov` maybe?
This makes it possible to pass the `Impl` directly to functions, instead
of having to pass each of the many fields one at a time. It also
simplifies matches in many cases.
The optimized MIR for closures is being encoded unconditionally, while
being unnecessary for cargo check. This turns out to be especially
costly with MIR inlining enabled, since it triggers computation of
optimized MIR for all callees that are being examined for inlining
purposes.
Skip encoding of optimized MIR for closures, enum constructors, struct
constructors, and trait fns when not doing codegen, like it is already
done for other items since 49433.
Turn type inhabitedness into a query to fix `exhaustive_patterns` perf
We measured in https://github.com/rust-lang/rust/pull/79394 that enabling the [`exhaustive_patterns` feature](https://github.com/rust-lang/rust/issues/51085) causes significant perf degradation. It was conjectured that the culprit is type inhabitedness checking, and [I hypothesized](https://github.com/rust-lang/rust/pull/79394#issuecomment-733861149) that turning this computation into a query would solve most of the problem.
This PR turns `tcx.is_ty_uninhabited_from` into a query, and I measured a 25% perf gain on the benchmark that stress-tests `exhaustiveness_patterns`. This more than compensates for the 30% perf hit I measured [when creating it](https://github.com/rust-lang/rustc-perf/pull/801). We'll have to measure enabling the feature again, but I suspect this fixes the perf regression entirely.
I'd like a perf run on this PR obviously.
I made small atomic commits to help reviewing. The first one is just me discovering the "revisions" feature of the testing framework.
I believe there's a push to move things out of `rustc_middle` because it's huge. I guess `inhabitedness/mod.rs` could be moved out, but it's quite small. `DefIdForest` might be movable somewhere too. I don't know what the policy is for that.
Ping `@camelid` since you were interested in following along
`@rustbot` modify labels: +A-exhaustiveness-checking
Since `DefIdForest` contains 0 or 1 elements the large majority of the
time, by allocating only in the >1 case we avoid almost all allocations,
compared to `Arc<SmallVec<[DefId;1]>>`. This shaves off 0.2% on the
benchmark that stresses uninhabitedness checking.
Remove much of the special-case handling around crate metadata
dependency tracking by replacing `DepKind::CrateMetadata` and the
pre-allocation of corresponding `DepNodes` with on-demand invocation
of the `crate_hash` query.
Make CTFE able to check for UB...
... by not doing any optimizations on the `const fn` MIR used in CTFE. This means we duplicate all `const fn`'s MIR now, once for CTFE, once for runtime. This PR is for checking the perf effect, so we have some data when talking about https://github.com/rust-lang/const-eval/blob/master/rfcs/0000-const-ub.md
To do this, we now have two queries for obtaining mir: `optimized_mir` and `mir_for_ctfe`. It is now illegal to invoke `optimized_mir` to obtain the MIR of a const/static item's initializer, an array length, an inline const expression or an enum discriminant initializer. For `const fn`, both `optimized_mir` and `mir_for_ctfe` work, the former returning the MIR that LLVM should use if the function is called at runtime. Similarly it is illegal to invoke `mir_for_ctfe` on regular functions.
This is all checked via appropriate assertions and I don't think it is easy to get wrong, as there should be no `mir_for_ctfe` calls outside the const evaluator or metadata encoding. Almost all rustc devs should keep using `optimized_mir` (or `instance_mir` for that matter).
Enhance type inference errors involving the `?` operator
This patch adds a special-cased note on type inference errors when the error span points to a `?` return. It also makes the primary label for such errors "cannot infer type of `?` error" in cases where before we would have only said "cannot infer type".
One beneficiary of this change is async blocks, where we can't explicitly annotate the return type and so may not generate any other help (#77880); this lets us at least print the error type we're converting from and anything we know about the type we can't fully infer. More generally, it signposts that an implicit conversion is happening that may have impeded type inference the user was expecting. We already do something similar for [mismatched type errors](2987785df3/src/test/ui/try-block/try-block-bad-type.stderr (L7)).
The check for a relevant `?` operator is built into the existing HIR traversal which looks for places that could be annotated to resolve the error. That means we could identify `?` uses anywhere in the function that output the type we can't infer, but this patch just sticks to adding the note if the primary span given for the error has the operator; if there are other expressions where the type occurs and one of them is selected for the error instead, it's more likely that the `?` operator's implicit conversion isn't the sole cause of the inference failure and that adding an additional diagnostic would just be noise. I added a ui test for one such case.
The data about the `?` conversion is passed around in a `UseDiagnostic` enum that in theory could be used to add more of this kind of note in the future. It was also just easier to pass around than something with a more specific name. There are some follow-up refactoring commits for the code that generates the error label, which was already pretty involved and made a bit more complicated by this change.
Rollup of 8 pull requests
Successful merges:
- #79757 (Replace tabs earlier in diagnostics)
- #80600 (Add `MaybeUninit` method `array_assume_init`)
- #80880 (Move some tests to more reasonable directories)
- #80897 (driver: Use `atty` instead of rolling our own)
- #80898 (Add another test case for #79808)
- #80917 (core/slice: remove doc comment about scoped borrow)
- #80927 (Replace a simple `if let` with the `matches` macro)
- #80930 (fix typo in trait method mutability mismatch help)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
driver: Use `atty` instead of rolling our own
Fixes#80888.
Rationale:
- `atty` is widely used in the Rust ecosystem
- We already use it (in `rustc_errors` and other places)
- We shouldn't be rolling our own TTY detector when there's a
widely-used, well-tested package that we can use
Replace tabs earlier in diagnostics
This replaces tabs earlier in the diagnostics emitting process, which allows various margin calculations to ignore the existence of tabs. It does add a string copy for the source lines that are emitted.
Fixes https://github.com/rust-lang/rust/issues/78438
r? `@estebank`
Serialize incr comp structures to file via fixed-size buffer
Reduce a large memory spike that happens during serialization by writing
the incr comp structures to file by way of a fixed-size buffer, rather
than an unbounded vector.
Effort was made to keep the instruction count close to that of the
previous implementation. However, buffered writing to a file inherently
has more overhead than writing to a vector, because each write may
result in a handleable error. To reduce this overhead, arrangements are
made so that each LEB128-encoded integer can be written to the buffer
with only one capacity and error check. Higher-level optimizations in
which entire composite structures can be written with one capacity and
error check are possible, but would require much more work.
The performance is mostly on par with the previous implementation, with
small to moderate instruction count regressions. The memory reduction is
significant, however, so it seems like a worth-while trade-off.
Rationale:
- `atty` is widely used in the Rust ecosystem
- We already use it (in `rustc_errors` and other places)
- We shouldn't be rolling our own TTY detector when there's a
widely-used, well-tested package that we can use
Suggest async {} for async || {}
Fixes#76011
This adds support for adding help diagnostics to the feature gating checks and
then uses it for the async_closure gate to add the extra bit of help
information as described in the issue.
