Stabilize move_ref_pattern
# Implementation
- Initially the rule was added in the run-up to 1.0. The AST-based borrow checker was having difficulty correctly enforcing match expressions that combined ref and move bindings, and so it was decided to simplify forbid the combination out right.
- The move to MIR-based borrow checking made it possible to enforce the rules in a finer-grained level, but we kept the rule in place in an effort to be conservative in our changes.
- In #68376, @Centril lifted the restriction but required a feature-gate.
- This PR removes the feature-gate.
Tracking issue: #68354.
# Description
This PR is to stabilize the feature `move_ref_pattern`, which allows patterns
containing both `by-ref` and `by-move` bindings at the same time.
For example: `Foo(ref x, y)`, where `x` is `by-ref`,
and `y` is `by-move`.
The rules of moving a variable also apply here when moving *part* of a variable,
such as it can't be referenced or moved before.
If this pattern is used, it would result in *partial move*, which means that
part of the variable is moved. The variable that was partially moved from
cannot be used as a whole in this case, only the parts that are still
not moved can be used.
## Documentation
- The reference (rust-lang/reference#881)
- Rust by example (rust-lang/rust-by-example#1377)
## Tests
There are many tests, but I think one of the comperhensive ones:
- [borrowck-move-ref-pattern-pass.rs](85fbf49ce0/src/test/ui/pattern/move-ref-patterns/borrowck-move-ref-pattern-pass.rs)
- [borrowck-move-ref-pattern.rs](85fbf49ce0/src/test/ui/pattern/move-ref-patterns/borrowck-move-ref-pattern.rs)
# Examples
```rust
#[derive(PartialEq, Eq)]
struct Finished {}
#[derive(PartialEq, Eq)]
struct Processing {
status: ProcessStatus,
}
#[derive(PartialEq, Eq)]
enum ProcessStatus {
One,
Two,
Three,
}
#[derive(PartialEq, Eq)]
enum Status {
Finished(Finished),
Processing(Processing),
}
fn check_result(_url: &str) -> Status {
// fetch status from some server
Status::Processing(Processing {
status: ProcessStatus::One,
})
}
fn wait_for_result(url: &str) -> Finished {
let mut previous_status = None;
loop {
match check_result(url) {
Status::Finished(f) => return f,
Status::Processing(p) => {
match (&mut previous_status, p.status) {
(None, status) => previous_status = Some(status), // first status
(Some(previous), status) if *previous == status => {} // no change, ignore
(Some(previous), status) => { // Now it can be used
// new status
*previous = status;
}
}
}
}
}
}
```
Before, we would have used:
```rust
match (&previous_status, p.status) {
(Some(previous), status) if *previous == status => {} // no change, ignore
(_, status) => {
// new status
previous_status = Some(status);
}
}
```
Demonstrating *partial move*
```rust
fn main() {
#[derive(Debug)]
struct Person {
name: String,
age: u8,
}
let person = Person {
name: String::from("Alice"),
age: 20,
};
// `name` is moved out of person, but `age` is referenced
let Person { name, ref age } = person;
println!("The person's age is {}", age);
println!("The person's name is {}", name);
// Error! borrow of partially moved value: `person` partial move occurs
//println!("The person struct is {:?}", person);
// `person` cannot be used but `person.age` can be used as it is not moved
println!("The person's age from person struct is {}", person.age);
}
```
Refactor io/buffered.rs into submodules
This pull request splits `BufWriter`, `BufReader`, `LineWriter`, and `LineWriterShim` (along with their associated tests) into separate submodules. It contains no functional changes. This change is being made in anticipation of adding another type of buffered writer which can be switched between line- and block-buffering mode.
Part of a series of pull requests resolving #60673.
mangling: mangle impl params w/ v0 scheme
This PR modifies v0 symbol mangling to include all generic parameters from impl blocks (not just those used in the self type) - an alternative fix to #75326.
```
original:
_RNCNvXCs4fqI2P2rA04_19impl_param_manglingINtB4_3FooppENtNtNtNtCsfnEnqCNU58Z_4core4iter6traits8iterator8Iterator4next0B4_
// |------------ B4_ ----------------|
// _R (N C (N v (X (C ((s 4fqI2p2rA04_) 19impl_param_mangling)) (I (N t B4_ 3Foo) pp E) (N t (N t (N t (N t (C ((s fnEnqCNU58Z_) 4core)) 4iter) 6traits) 8iterator) 8Iterator)) 4next) 0) B4_
modified:
_RNvXINICs4fqI2P2rA04_11issue_753260pppEINtB5_3FooppENtNtNtNtCsfnEnqCNU58Z_4core4iter6traits8iterator8Iterator4nextB5_
// _R (N v (X (I (N I (C ((s 4fqI2P2rA04_) 11issue_75326)) 0) ppp E) (I (N t B5_ 3Foo) pp E) (N t (N t (N t (N t (C ((s fnEnqCNU58Z_) 4core)) 4iter) 6traits) 8iterator) 8Iterator)) 4next) B5_
// | ^ |
// | | |
// | new impl namespace |
```
~~Submitted as a draft as after some discussion w/ @eddyb, I'm going to do some investigation into (yet more alternative) changes to polymorphization that might remove the necessity for this.~~
r? @eddyb
Add `str::{Split,RSplit,SplitN,RSplitN,SplitTerminator,RSplitTerminator,SplitInclusive}::as_str` methods
tl;dr this allows viewing unyelded part of str-split-iterators, like so:
```rust
let mut split = "Mary had a little lamb".split(' ');
assert_eq!(split.as_str(), "Mary had a little lamb");
split.next();
assert_eq!(split.as_str(), "had a little lamb");
split.by_ref().for_each(drop);
assert_eq!(split.as_str(), "");
```
--------------
This PR adds semi-identical `as_str` methods to most str-split-iterators with signatures like `&'_ Split<'a, P: Pattern<'a>> -> &'a str` (Note: output `&str` lifetime is bound to the `'a`, not the `'_`). The methods are similar to [`Chars::as_str`]
`SplitInclusive::as_str` is under `"str_split_inclusive_as_str"` feature gate, all other methods are under `"str_split_as_str"` feature gate.
Before this PR you had to sum `len`s of all yielded parts or collect into `String` to emulate `as_str`.
[`Chars::as_str`]: https://doc.rust-lang.org/core/str/struct.Chars.html#method.as_str
ensure arguments are included in count mismatch span
The current diagnostic isn't very helpful if the function header spans multiple lines. Lines comprising the function signature may be elided to keep the diagnostic short, but these lines are essential to fixing the error. This is made worse when the function has a body, because the last two lines of the span are then dedicated to showing the end of the body, which is irrelevant.
This PR changes the span to be a multispan made up of the header and the the arguments, ensuring they won't be elided. It also discards the function body from the span.
[Old](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=f92d9f81a8c9416f0f04e4e09923b6d4):
```
error[E0061]: this function takes 6 arguments but 1 argument was supplied
--> src/main.rs:18:5
|
1 | / fn bar(
2 | | a: i32,
3 | | b: i32,
4 | | c: i32,
... |
14 | | println!("{}", f);
15 | | }
| |_- defined here
...
18 | bar(1);
| ^^^ - supplied 1 argument
| |
| expected 6 arguments
```
New:
```
error[E0061]: this function takes 6 arguments but 1 argument was supplied
--> $DIR/not-enough-arguments.rs:28:3
|
LL | bar(1);
| ^^^ - supplied 1 argument
| |
| expected 6 arguments
|
note: function defined here
--> $DIR/not-enough-arguments.rs:9:1
|
LL | / fn bar(
LL | | a: i32,
| | ^^^^^^^
LL | | b: i32,
| | ^^^^^^^
LL | | c: i32,
| | ^^^^^^^
LL | | d: i32,
| | ^^^^^^^
LL | | e: i32,
| | ^^^^^^^
LL | | f: i32,
| | ^^^^^^^
LL | | ) {
| |_^
```
This commit improves the tuple struct case added in rust-lang/rust#77341
so that the context is mentioned in more of the message.
Signed-off-by: David Wood <david@davidtw.co>
This commit improves the diagnostic modified in rust-lang/rust#77341 to
suggest not only those variants which do not have fields, but those with
fields (by suggesting with placeholders).
Signed-off-by: David Wood <david@davidtw.co>
No more target.target
Two main changes of this PR:
* Turn `target_pointer_width` into an integer and rename to `pointer_width`.
The compiler only allowed three valid values for the width anyways.
An integer is more natural for this value, and saves a few allocations
and copies.
* Remove the `rustc_session::config::Config` wrapper and replace it with
its inner member `Target`. Aka. no more `target.target`. This makes life so
much easier, but it also causes a ton of downstream breakage.
Some changes of this PR were done using tooling. These tooling-made changes
were isolated to their own commits to make review easier.
It's best to review the PR commit-by-commit.
Miri PR: https://github.com/rust-lang/miri/pull/1583
I request p=10 bors priority because of the breakage.
Ideally, we would want to handle a broader set of cases to fully fix the
underlying bug here. That is currently relatively expensive at compile and
runtime, so we don't do that for now.
This commit modifies v0 symbol mangling to include all generic
parameters from impl blocks (not just those used in the self type).
Signed-off-by: David Wood <david@davidtw.co>
This commit adjust `#[rustc_symbol_name]` so that it can be applied to
non-monomorphic functions without producing an ICE.
Signed-off-by: David Wood <david@davidtw.co>
The wrapper type led to tons of target.target
across the compiler. Its ptr_width field isn't
required any more, as target_pointer_width
is already present in parsed form.
Preparation for a subsequent change that replaces
rustc_target::config::Config with its wrapped Target.
On its own, this commit breaks the build. I don't like making
build-breaking commits, but in this instance I believe that it
makes review easier, as the "real" changes of this PR can be
seen much more easily.
Result of running:
find compiler/ -type f -exec sed -i -e 's/target\.target\([)\.,; ]\)/target\1/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target\.target$/target/g' {} \;
find compiler/ -type f -exec sed -i -e 's/target.ptr_width/target.pointer_width/g' {} \;
./x.py fmt
Rename target_pointer_width to pointer_width because it is already
member of the Target struct.
The compiler supports only three valid values for target_pointer_width:
16, 32, 64. Thus it can safely be turned into an int.
This means less allocations and clones as well as easier handling of the type.
Also change target_pointer_width to pointer_width.
Preparation for a subsequent type change of
target_pointer_width to an integer together with a rename
to pointer_width.
On its own, this commit breaks the build. I don't like making
build-breaking commits, but in this instance I believe that it
makes review easier, as the "real" changes of this PR can be
seen much more easily.
Result of running:
find compiler/rustc_target/src/spec/ -type f -exec sed -i -e 's/target_pointer_width: "\(.*\)"\..*,/pointer_width: \1,/g' {} \;
Replace tuple of infer vars for upvar_tys with single infer var
This commit allows us to decide the number of captures required after
completing capture ananysis, which is required as part of implementing
RFC-2229.
closes https://github.com/rust-lang/project-rfc-2229/issues/4
r? `@nikomatsakis`
Detect configuration for LLVM during setup
This is a first draft to address #77579, setting `download-ci-llvm` to true on Linux, but I could also implement the `if-available` setting mentioned in the issue.
On other platforms I was thinking about using [the which crate](https://crates.io/crates/which), if adding a dependency on it is considered okay of course, to detect the presence of `llvm-config` in the path, and use it if found. Still a work in progress of course.
Update books
## reference
5 commits in 56a13c082ee90736c08d6abdcd90462517b703d3..1b78182e71709169dc0f1c3acdc4541b6860e1c4
2020-09-14 23:20:16 -0700 to 2020-10-11 13:53:47 -0700
- Specify that SSE4.1 includes SSSE3 instead of SSE3 (rust-lang-nursery/reference#892)
- Fix mutable expressions that can be dereferenced (rust-lang-nursery/reference#890)
- Fix grammar in memory model (rust-lang-nursery/reference#889)
- Add style checks. (rust-lang-nursery/reference#886)
- Add description for LUB Coercion (rust-lang-nursery/reference#808)
## book
1 commits in cb28dee95e5e50b793e6ba9291c5d1568d3ad72e..451a1e30f2dd137aa04e142414eafb8d05f87f84
2020-09-09 10:06:00 -0500 to 2020-10-05 09:11:18 -0500
- clarify description of when ? can be used (rust-lang/book#2471)
## rust-by-example
1 commits in 7d3ff1c12db08a847a57a054be4a7951ce532d2d..152475937a8d8a1f508d8eeb57db79139bc803d9
2020-09-28 15:54:25 -0300 to 2020-10-09 09:29:50 -0300
- Add 1.45.0 cast documentation (rust-lang/rust-by-example#1384)
## embedded-book
2 commits in dd310616308e01f6cf227f46347b744aa56b77d9..79ab7776929c66db83203397958fa7037d5d9a30
2020-09-26 08:54:08 +0000 to 2020-10-12 08:00:05 +0000
- llvm-objdump: Use two hyphens in flags to objdump (rust-embedded/book#270)
- Start/hardware: clarify which file needs tweaking (rust-embedded/book#266)
