| Age | Commit message (Collapse) | Author | Lines |
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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.
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By eliminating some unnecessary methods, and moving/renaming some
functions that look like they might be methods but aren't.
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It's simpler that way.
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It doesn't need to return an `Option`.
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Specifically:
- Remove dead methods: fold_usize, fold_meta_items, fold_opt_bounds.
- Remove useless methods: fold_global_asm, fold_range_end.
- Inline and remove unnecessary methods: fold_item_simple,
fold_foreign_item_simple.
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resolves #57773
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`TokenStream` is now almost identical to `ThinTokenStream`. This commit
removes the latter, replacing it with the former.
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Because it's an extra type layer that doesn't really help; in a couple
of places it actively gets in the way, and overall removing it makes the
code nicer. It does, however, move `tokenstream::TokenTree` further away
from the `TokenTree` in `quote.rs`.
More importantly, this change reduces the size of `TokenStream` from 48
bytes to 40 bytes on x86-64, which is enough to slightly reduce
instruction counts on numerous benchmarks, the best by 1.5%.
Note that `open_tt` and `close_tt` have gone from being methods on
`Delimited` to associated methods of `TokenTree`.
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refactor: use shorthand fields
refactor: use shorthand for single fields everywhere (excluding tests).
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Track whether module declarations are inline (fixes #12590)
To track whether module declarations are inline I added a field `inline: bool` to `ast::Mod`. The main use case is for pretty to know whether it should render the items associated with the module, but perhaps there are use cases for this information to not be forgotten in the AST.
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refactor match guard
This is the first step to implement RFC 2294: if-let-guard. Tracking issue: https://github.com/rust-lang/rust/issues/51114
The second step should be introducing another variant `IfLet` in the Guard enum. I separated them into 2 PRs for the convenience of reviewers.
r? @petrochenkov
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Use optimized SmallVec implementation
This PR replaces current SmallVec implementation with the one from the Servo project.
Closes https://github.com/rust-lang/rust/issues/51640
r? @Mark-Simulacrum
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Implement try block expressions
I noticed that `try` wasn't a keyword yet in Rust 2018, so...
~~Fixes https://github.com/rust-lang/rust/issues/52604~~ That was fixed by PR https://github.com/rust-lang/rust/pull/53135
cc https://github.com/rust-lang/rust/issues/31436 https://github.com/rust-lang/rust/issues/50412
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(Not `Try` since `QuestionMark` is using that.)
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Our implementation ends up changing the `PatKind::Range` variant in the
AST to take a `Spanned<RangeEnd>` instead of just a `RangeEnd`, because
the alternative would be to try to infer the span of the range operator
from the spans of the start and end subexpressions, which is both
hideous and nontrivial to get right (whereas getting the change to the
AST right was a simple game of type tennis).
This is concerning #51043.
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This is gated on edition 2018 & the `async_await` feature gate.
The parser will accept `async fn` and `async unsafe fn` as fn
items. Along the same lines as `const fn`, only `async unsafe fn`
is permitted, not `unsafe async fn`.The parser will not accept
`async` functions as trait methods.
To do a little code clean up, four fields of the function type
struct have been merged into the new `FnHeader` struct: constness,
asyncness, unsafety, and ABI.
Also, a small bug in HIR printing is fixed: it previously printed
`const unsafe fn` as `unsafe const fn`, which is grammatically
incorrect.
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It's so confusing to have everything having the same name, at least while refactoring.
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