`opaque::Decoder::read_str` is very hot within `rustc` due to its use in
the reading of crate metadata, and it currently returns a `String`. This
commit changes it to instead return a `Cow<str>`, which avoids a heap
allocation.
This change reduces the number of calls to `malloc` by almost 10% in
some benchmarks.
This is a [breaking-change] to libserialize.
Specific error message for missplaced doc comments
Identify when documetation comments have been missplaced in the following places:
* After a struct element:
```rust
// file.rs:
struct X {
a: u8 /** document a */,
}
```
```bash
$ rustc file.rs
file.rs:2:11: 2:28 error: found documentation comment that doesn't
document anything
file.rs:2 a: u8 /** document a */,
^~~~~~~~~~~~~~~~~
file.rs:2:11: 2:28 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
* As the last line of a struct:
```rust
// file.rs:
struct X {
a: u8,
/// incorrect documentation
}
```
```bash
$ rustc file.rs
file.rs:3:5: 3:27 error: found a documentation comment that doesn't
document anything
file.rs:3 /// incorrect documentation
^~~~~~~~~~~~~~~~~~~~~~
file.rs:3:5: 3:27 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
* As the last line of a `fn`:
```rust
// file.rs:
fn main() {
let x = 1;
/// incorrect documentation
}
```
```bash
$ rustc file.rs
file.rs:3:5: 3:27 error: found a documentation comment that doesn't
document anything
file.rs:3 /// incorrect documentation
^~~~~~~~~~~~~~~~~~~~~~
file.rs:3:5: 3:27 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
Fix#27429, #30322
Simplify the macro hygiene algorithm
This PR removes renaming from the hygiene algorithm and treats differently marked identifiers as unequal.
This change makes the scope of identifiers in `macro_rules!` items empty. That is, identifiers in `macro_rules!` definitions do not inherit any semantics from the `macro_rules!`'s scope.
Since `macro_rules!` macros are items, the scope of their identifiers "should" be the same as that of other items; in particular, the scope should contain only items. Since all items are unhygienic today, this would mean the scope should be empty.
However, the scope of an identifier in a `macro_rules!` statement today is the scope that the identifier would have if it replaced the `macro_rules!` (excluding anything unhygienic, i.e. locals only).
To continue to support this, this PR tracks the scope of each `macro_rules!` and uses it in `resolve` to ensure that an identifier expanded from a `macro_rules!` gets a chance to resolve to the locals in the `macro_rules!`'s scope.
This PR is a pure refactoring. After this PR,
- `syntax::ext::expand` is much simpler.
- We can expand macros in any order without causing problems for hygiene (needed for macro modularization).
- We can deprecate or remove today's `macro_rules!` scope easily.
- Expansion performance improves by 25%, post-expansion memory usage decreases by ~5%.
- Expanding a block is no longer quadratic in the number of `let` statements (fixes#10607).
r? @nrc
Identify when documetation comments have been missplaced in the
following places:
* After a struct element:
```rust
// file.rs:
struct X {
a: u8 /** document a */,
}
```
```bash
$ rustc file.rs
file.rs:2:11: 2:28 error: found documentation comment that doesn't
document anything
file.rs:2 a: u8 /** document a */,
^~~~~~~~~~~~~~~~~
file.rs:2:11: 2:28 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
* As the last line of a struct:
```rust
// file.rs:
struct X {
a: u8,
/// incorrect documentation
}
```
```bash
$ rustc file.rs
file.rs:3:5: 3:27 error: found a documentation comment that doesn't
document anything
file.rs:3 /// incorrect documentation
^~~~~~~~~~~~~~~~~~~~~~
file.rs:3:5: 3:27 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
* As the last line of a `fn`:
```rust
// file.rs:
fn main() {
let x = 1;
/// incorrect documentation
}
```
```bash
$ rustc file.rs
file.rs:3:5: 3:27 error: found a documentation comment that doesn't
document anything
file.rs:3 /// incorrect documentation
^~~~~~~~~~~~~~~~~~~~~~
file.rs:3:5: 3:27 help: doc comments must come before what they document,
maybe a comment was intended with `//`?
```
Fix#27429, #30322
Automated conversion using the untry tool [1] and the following command:
```
$ find -name '*.rs' -type f | xargs untry
```
at the root of the Rust repo.
[1]: https://github.com/japaric/untry
This PR implements [RFC 1192](https://github.com/rust-lang/rfcs/blob/master/text/1192-inclusive-ranges.md), which is triple-dot syntax for inclusive range expressions. The new stuff is behind two feature gates (one for the syntax and one for the std::ops types). This replaces the deprecated functionality in std::iter. Along the way I simplified the desugaring for all ranges.
This is my first contribution to rust which changes more than one character outside of a test or comment, so please review carefully! Some of the individual commit messages have more of my notes. Also thanks for putting up with my dumb questions in #rust-internals.
- For implementing `std::ops::RangeInclusive`, I took @Stebalien's suggestion from https://github.com/rust-lang/rfcs/pull/1192#issuecomment-137864421. It seemed to me to make the implementation easier and increase type safety. If that stands, the RFC should be amended to avoid confusion.
- I also kind of like @glaebhoerl's [idea](https://github.com/rust-lang/rfcs/pull/1254#issuecomment-147815299), which is unified inclusive/exclusive range syntax something like `x>..=y`. We can experiment with this while everything is behind a feature gate.
- There are a couple of FIXMEs left (see the last commit). I didn't know what to do about `RangeArgument` and I haven't added `Index` impls yet. Those should be discussed/finished before merging.
cc @Gankro since you [complained](https://www.reddit.com/r/rust/comments/3xkfro/what_happened_to_inclusive_ranges/cy5j0yq)
cc #27777#30877rust-lang/rust#1192rust-lang/rfcs#1254
relevant to #28237 (tracking issue)
nodes in statement position.
Extended #[cfg] folder to allow removal of statements, and
of expressions in optional positions like expression lists and trailing
block expressions.
Extended lint checker to recognize lint levels on expressions and
locals.
Make sure Name, SyntaxContext and Ident are passed by value
Make sure Idents don't serve as keys (or parts of keys) in maps, Ident comparison is not well defined
