Allow #[repr(align(x))] on enums (#57996)
Tracking issue: #57996
Implements an extension of [RFC 1358](https://github.com/rust-lang/rfcs/blob/master/text/1358-repr-align.md) behind a feature flag (`repr_align_enum`). Originally introduced here for structs: #39999.
It seems like only HIR-level changes are required, since enums are already aware of their alignment (due to alignment of their limbs).
cc @bitshifter
Overhaul `syntax::fold::Folder`.
This PR changes `syntax::fold::Folder` from a functional style
(where most methods take a `T` and produce a new `T`) to a more
imperative style (where most methods take and modify a `&mut T`), and
renames it `syntax::mut_visit::MutVisitor`.
This makes the code faster and more concise.
This commit changes `syntax::fold::Folder` from a functional style
(where most methods take a `T` and produce a new `T`) to a more
imperative style (where most methods take and modify a `&mut T`), and
renames it `syntax::mut_visit::MutVisitor`.
The first benefit is speed. The functional style does not require any
reallocations, due to the use of `P::map` and
`MoveMap::move_{,flat_}map`. However, every field in the AST must be
overwritten; even those fields that are unchanged are overwritten with
the same value. This causes a lot of unnecessary memory writes. The
imperative style reduces instruction counts by 1--3% across a wide range
of workloads, particularly incremental workloads.
The second benefit is conciseness; the imperative style is usually more
concise. E.g. compare the old functional style:
```
fn fold_abc(&mut self, abc: ABC) {
ABC {
a: fold_a(abc.a),
b: fold_b(abc.b),
c: abc.c,
}
}
```
with the imperative style:
```
fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
visit_a(a);
visit_b(b);
}
```
(The reductions get larger in more complex examples.)
Overall, the patch removes over 200 lines of code -- even though the new
code has more comments -- and a lot of the remaining lines have fewer
characters.
Some notes:
- The old style used methods called `fold_*`. The new style mostly uses
methods called `visit_*`, but there are a few methods that map a `T`
to something other than a `T`, which are called `flat_map_*` (`T` maps
to multiple `T`s) or `filter_map_*` (`T` maps to 0 or 1 `T`s).
- `move_map.rs`/`MoveMap`/`move_map`/`move_flat_map` are renamed
`map_in_place.rs`/`MapInPlace`/`map_in_place`/`flat_map_in_place` to
reflect their slightly changed signatures.
- Although this commit renames the `fold` module as `mut_visit`, it
keeps it in the `fold.rs` file, so as not to confuse git. The next
commit will rename the file.
Include the span of attributes of the lhs to the span of the assignment expression
This PR adds the span of attributes of the lhs to the span of the assignment expression. Currently with the following code, `#[attr]` is not included to the span of the assignment (`foo = true`).
```rust
#[attr]
foo = true;
```
The rational behind this change is that as libsyntax user I expect the span of the parent node includes every span of child nodes.
cc https://github.com/rust-lang/rustfmt/issues/3313, https://github.com/rust-lang/rust/issues/15701.
proc_macro: make `TokenStream::from_streams` pre-allocate its vector.
This requires a pre-pass over the input streams. But that is cheap compared to the quadratic blowup associated with reallocating the accumulating vector on-the-fly.
Fix#57735
Add suggestion for duplicated import.
Fixes#52891.
This PR adds a suggestion when a import is duplicated (ie. the same name
is used twice trying to import the same thing) to remove the second
import.
Add suggestions to deprecation lints
Clippy used to do this suggestion, but the clippy lints happen after the deprecation lints so we ended up never seeing the structured suggestions.
This commit adds a suggestion when a import is duplicated (ie. the same name
is used twice trying to import the same thing) to remove the second
import.
Add MOVBE x86 CPU feature
I have no idea if this is correct. I basically copied the ADX feature. I verified the feature is also called `movbe` in LLVM.
I marked this to become stable immediately, as part of the RFC 2045.
r? @alexcrichton
This requires a pre-pass over the input streams. But that is cheap
compared to the quadratic blowup associated with reallocating the
accumulating vector on-the-fly.
Suggest removing leading left angle brackets.
Fixes#57819.
This PR adds errors and accompanying suggestions as below:
```
bar::<<<<<T as Foo>::Output>();
^^^ help: remove extra angle brackets
```
r? @estebank
Implement optimize(size) and optimize(speed) attributes
This PR implements both `optimize(size)` and `optimize(speed)` attributes.
While the functionality itself works fine now, this PR is not yet complete: the code might be messy in places and, most importantly, the compiletest must be improved with functionality to run tests with custom optimization levels. Otherwise the new attribute cannot be tested properly. Oh, and not all of the RFC is implemented – attribute propagation is not implemented for example.
# TODO
* [x] Improve compiletest so that tests can be written;
* [x] Assign a proper error number (E9999 currently, no idea how to allocate a number properly);
* [ ] Perhaps reduce the duplication in LLVM attribute assignment code…
distinguish "no data" from "heterogeneous" in ABI
Ignore zero-sized types when computing whether something is a homogeneous aggregate, except be careful of VLA.
cc #56877
r? @arielb1
cc @eddyb
This commit extends existing suggestions to move lifetimes before types
in generic arguments to also suggest moving types behind associated type
bindings.
Add suggestion for incorrect field syntax.
Fixes#57684.
This commit adds a suggestion when a `=` character is used when
specifying the value of a field in a struct constructor incorrectly
instead of a `:` character.
r? @estebank
Remove quote_*! macros
This deletes a considerable amount of test cases, some of which we may want to keep. I'm not entirely certain what the primary intent of many of them was; if we should keep them I can attempt to edit each case to continue compiling without the quote_*! macros involved.
Fixes#46849.
Fixes#12265.
Fixes#12266.
Fixes#26994.
r? @Manishearth
Add error for trailing angle brackets.
Fixes#54521.
This PR adds a error (and accompanying machine applicable
suggestion) for trailing angle brackets on function calls with a
turbofish.
r? @estebank
