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.
resolve: Simplify built-in macro table
We don't use full `SyntaxExtension`s from the table, only `SyntaxExtensionKind`s, and `Ident` in `register_builtin_macro` always had dummy span. This PR removes unnecessary data from the table and related function signatures.
Noticed when reviewing #80850.
Explain method-call move errors in loops
PR #73708 added a more detailed explanation of move errors that occur
due to a call to a method that takes `self`. This PR extends that logic
to work when a move error occurs due to a method call in the previous
iteration of a loop.
Split a func into cold/hot parts, reducing binary size
I noticed that the Size::bits function is called in many places,
and is inlined into them. On x86_64-pc-windows-msvc, this function
is inlined 527 times, and compiled separately (non-inlined) 3 times.
Each of those inlined calls contains code that panics. This commit
moves the `panic!` call into a separate function and marks that
function with `#[cold]`.
This reduces binary size by 24 KB. Not much, but it's something.
Changes like this often reduce pressure on instruction-caches,
since it reduces the amount of code that is inlined into hot code
paths. Or more precisely, it removes cold code from hot cache lines.
Use correct ABI for wasm32 by default
Introduces `wasm32-unknown-bindgen` for those wishing to use the bindgen compat abi. `wasm32-*` now uses the correct abi by default.
Fixes https://github.com/rustwasm/team/issues/291
The signed LEB128 decoding function used a hardcoded constant of 64
instead of the number of bits in the type of integer being decoded,
which resulted in incorrect results for some inputs. Fix this, make the
decoding more consistent with the unsigned version, and increase the
LEB128 encoding and decoding test coverage.
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.
log-color: Detect TTY based on stderr, not stdout
Fixes#78435 (again).
Logging goes to stderr, not stdout, so we should base our automated
detection on stderr instead of stdout.
Thanks to Ralf Jung for noticing and reporting the bug!
r? `@oli-obk`
cc `@RalfJung`
Add ABI argument to `find_mir_or_eval_fn`
Add ABI argument for called function in `find_mir_or_eval_fn` and
`call_extra_fn`. Useful for comparing with expected ABI in interpreters.
Related to [miri/1631](https://github.com/rust-lang/miri/issues/1631)
r? `@RalfJung`
Use standard formatting for "rust-call" ABI message
Nearly all error messages start with a lowercase letter and don't use
articles - instead they refer to the plural case.
resolve: Scope visiting doesn't need an `Ident`
Resolution scope visitor (`fn visit_scopes`) currently takes an `Ident` parameter, but it doesn't need a full identifier, or even its span, it only needs the `SyntaxContext` part.
The `SyntaxContext` part is necessary because scope visitor has to jump to macro definition sites, so it has to be directed by macro expansion information somehow.
I think it's clearer to pass only the necessary part.
Yes, usually visiting happens as a part of an identifier resolution, but in cases like collecting traits in scope (#80765) or collecting typo suggestions that's not the case.
r? `@matthewjasper`
Logging goes to stderr, not stdout, so we should base our automated
detection on stderr instead of stdout.
Thanks to Ralf Jung for noticing and reporting the bug!
Add ABI argument for called function in `find_mir_or_eval_fn` and
`call_extra_fn`. Useful for comparing with expected ABI in interpreters.
Related to [miri/1631](https://github.com/rust-lang/miri/issues/1631)
Allow #[rustc_builtin_macro = "name"]
This adds the option of specifying the name of a builtin macro in the `#[rustc_builtin_macro]` attribute: `#[rustc_builtin_macro = "name"]`.
This makes it possible to have both `std::panic!` and `core::panic!` as a builtin macro, by using different builtin macro names for each. This is needed to implement the edition-specific behaviour of the panic macros of RFC 3007.
Also removes `SyntaxExtension::is_derive_copy`, as the macro name (e.g. `sym::Copy`) is now tracked and provides that information directly.
r? ``@petrochenkov``
Use correct span for structured suggestion
On structured suggestion for `let` -> `const` and `const` -> `let`, use
a proper `Span` and update tests to check the correct application.
Follow up to #80012.
Improve core::ptr::drop_in_place debuginfo
* Use span of the dropped type as function span when possible.
* Rename symbol from `core::ptr::drop_in_place::$hash` to `{{drop}}::<$TYPE>::$hash`.
Fixes#77465
(I haven't yet updated the tests)
Rustdoc: Fix macros 2.0 and built-in derives being shown at the wrong path
Fixes#74355
- ~~waiting on author + draft PR since my code ought to be cleaned up _w.r.t._ the way I avoid the `.unwrap()`s:~~
- ~~dummy items may avoid the first `?`,~~
- ~~but within the module traversal some tests did fail (hence the second `?`), meaning the crate did not possess the exact path of the containing module (`extern` / `impl` blocks maybe? I'll look into that).~~
r? `@jyn514`
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.
Don't mark `force_query_with_job` as `inline(always)`
It's rather large, and using `inline(always)` forces it to be recompiled
in each calling crate. Hopefully this change will help with #65031. I intentionally only removed inline from `force_query_with_job` because the other functions are tiny and I wanted to measure this change on its own.
This may conflict with https://github.com/rust-lang/rust/issues/78780. I am not sure if it will hurt or help.
cc `@cjgillot`
Use an empty `TokenCursorFrame` stack when capturing tokens
We will never need to pop past our starting frame during token
capturing. Using an empty stack allows us to avoid pointless heap
allocations/deallocations.
This makes it possible to have both std::panic and core::panic as a
builtin macro, by using different builtin macro names for each.
Also removes SyntaxExtension::is_derive_copy, as the macro name (e.g.
sym::Copy) is now tracked and provides that information directly.
Make target-cpu=native detect individual features
This PR makes target-cpu=native check for and enable/disable individual features instead of detecting and targeting a CPU by name. This brings the flag's behavior more in line with clang and gcc and ensures that the host actually supports each feature that we are compiling for.
This should resolve issues with miscompilations on e.g. "Haswell" Pentiums and Celerons that lack support for AVX, and also enable support for `aes` on Broadwell processors that support it. It should also resolve issues with failing to detect feature support in newer CPUs that aren't yet known by LLVM (see: #80633).
Fixes#54688Fixes#48464Fixes#38218
We will never need to pop past our starting frame during token
capturing. Using an empty stack allows us to avoid pointless heap
allocations/deallocations.
PR #73708 added a more detailed explanation of move errors that occur
due to a call to a method that takes `self`. This PR extends that logic
to work when a move error occurs due to a method call in the previous
iteration of a loop.
Access query (DepKind) metadata through fields
This refactors the access to query definition metadata (attributes such as eval always, anon, has_params) and loading/forcing functions to generate a number of structs, instead of matching on the DepKind enum. This makes access to the fields cheaper to compile. Using a struct means that finding the metadata for a given query is just an offset away; previously the match may have been compiled to a jump table but likely not completely inlined as we expect here.
A previous attempt explored a similar strategy, but using trait objects in #78314 that proved less effective, likely due to higher overheads due to forcing dynamic calls and poorer cache utilization (all metadata is fairly densely packed with this PR).
Optimize away some `fs::metadata` calls.
This also eliminates a use of a `Path` convenience function, in support
of #80741, refactoring `std::path` to focus on pure data structures and
algorithms.
Make sure rust-call errors occur correctly for traits
Fixes#79669
Adds trait method resolution to the error, and adds UI tests to ensure it doesn't happen again. Opening as draft because I'm getting weird link errors from unrelated code on my machine, and want to see what CI thinks.
On structured suggestion for `let` -> `const` and `const` -> `let`, use
a proper `Span` and update tests to check the correct application.
Follow up to #80012.
rustc_parse: Better spans for synthesized token streams
I think using the nonterminal span for synthesizing its tokens is a better approximation than using `DUMMY_SP` or the attribute span like #79472 did in `expand.rs`.
r? `@Aaron1011`
MIR Inline is incompatible with coverage
Fixes: #80060
Fixed by disabling inlining if `-Zinstrument-coverage` is set.
The PR also adds additional use cases to the coverage test for doctests.
r? `@wesleywiser`
cc: `@tmandry`
Make `ExpnData` fields `krate` and `orig_id` private
These fields are only used by hygiene serialized, and should not be
accessed by anything outside of `rustc_span`.
Optimize DST field access
For
struct X<T: ?Sized>(T)
struct Y<T: ?Sized>(u8, T)
the offset of the unsized field is
0
mem::align_of_val(&self.1)
respectively. This patch changes the expression used to compute these
offsets so that the optimizer can perform this optimization.
Consider
```rust
fn f(x: &X<dyn Any>) -> &dyn Any {
&x.0
}
```
Before:
```asm
test:
movq %rsi, %rdx
movq 16(%rsi), %rax
leaq -1(%rax), %rcx
negq %rax
andq %rcx, %rax
addq %rdi, %rax
retq
```
After:
```asm
test:
movq %rsi, %rdx
movq %rdi, %rax
retq
```
Optimize away a `fs::metadata` call.
This also eliminates a use of a `Path` convenience function, in support
of #80741, refactoring `std::path` to focus on pure data structures and
algorithms.
* Rename `ModuleData.normal_ancestor_id` to `nearest_parent_mod`
`normal_ancestor_id` is a very confusing name if you don't already
understand what it means. Adding docs helps, but using a clearer and
more obvious name is also important.
* Rename `Resolver::nearest_mod_parent` to `nearest_parent_mod`
* Add more docs
This also eliminates a use of a `Path` convenience function, in support
of #80741, refactoring `std::path` to focus on pure data structures and
algorithms.
This also eliminates a use of a `Path` convenience function, in support
of #80741, refactoring `std::path` to focus on pure data structures and
algorithms.
I noticed that the Size::bits function is called in many places,
and is inlined into them. On x86_64-pc-windows-msvc, this function
is inlined 527 times, and compiled separately (non-inlined) 3 times.
Each of those inlined calls contains code that panics. This commit
moves the `panic!` call into a separate function and marks that
function with `#[cold]`.
This reduces binary size by 24 KB. By itself, that's not a substantial
reduction. However, changes like this often reduce pressure on
instruction-caches, since it reduces the amount of code that is inlined
into hot code paths. Or more precisely, it removes cold code from hot
cache lines. It also removes all conditionals from Size::bits(),
which is called in many places.
Move variable into the only branch where it is relevant
At the `if` branch `filter` (the `let` binding) is `None` iff `filter` (the parameter) was `None`.
We can branch on the parameter, move the binding into the `if`, and the complexity of handling
`Option<Option<_>` largely dissolves.
`@rustbot` modify labels +C-cleanup +T-compiler
Note: I have no idea how hot this code is. If this method frequently gets called with a `None` filter, there might be a small perf improvement.
Add check for `[T;N]`/`usize` mismatch in astconv
Helps clarify the issue in #80506
by adding a specific check for mismatches between [T;N] and usize.
r? `@lcnr`
use PlaceRef more consistently instead of loosely coupled local+projection
Instead of working directly with the `projections` array, use `iter_projections` and `last_projection`. This avoids having to construct new `PlaceRef` from the pieces everywhere.
I only did this for a few files, to see how people think about this. If y'all are happy with this, I'll open an E-mentor issue to complete this. I grepped for `Place::ty_from` to find the places that need adjusting -- this could miss some, but I am not sure what else to grep for.
Add note to non-exhaustive match on reference to empty
Rust prints "type `&A` is non-empty" even is A is empty.
This is the intended behavior, but can be confusing.
This commit adds a note to non-exhaustive pattern errors if they are a
reference to something uninhabited.
I did not add tests to check that the note is not shown for
non-references or inhabited references, because this is already done
in other tests.
Maybe the added test is superfluous, because
`always-inhabited-union-ref` already checks for this case.
This does not handle &&Void or &&&void etc. I could add those as special
cases as well and ignore people who need quadruple
references.
Fixes#78123
Allow references to interior mutable data behind a feature gate
supercedes #80373 by simply not checking for interior mutability on borrows of locals that have `StorageDead` and thus can never be leaked to the final value of the constant
tracking issue: https://github.com/rust-lang/rust/issues/80384
r? `@RalfJung`
Rust prints "type `&A` is non-empty" even is A is empty.
This is the intended behavior, but can be confusing.
This commit adds a note to non-exhaustive pattern errors if they are a
reference to something uninhabited.
I did not add tests to check that the note is not shown for
non-references or inhabited references, because this is already done
in other tests.
Maybe the added test is superfluous, because
`always-inhabited-union-ref` already checks for this case.
This does not handle &&Void or &&&void etc. I could add those as special
cases as well and ignore people who need quadruple
references.
Fixes#78123
Clean up in `each_child_of_item`
This PR hopes to eliminate some of the surprising elements I encountered while reading the function.
- `macros_only` is checked against inside the loop body, but if it is `true`, the loop is skipped anyway
- only query `span` when relevant
- no need to allocate attribute vector
