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
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 | | ) {
| |_^
```
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.
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>
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.
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)
Provide better documentation and help messages for x.py setup
Closes: #77861
I have split this up into tiny comments because I find it clearer this way. Feel free to squash it.
We need a fresh input buffer each time, or we reuse the previous
data (since `read_line` appends).
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Put all()'s otuput in the order we want to print things in, and add a
comment about why they are in this order. Provide purpose() and
all_for_help(). Use these things everywhere.
Move all the abbrev character ("a", "b", etc.) processing into
interactive_path.
No functional change.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
Rollup of 8 pull requests
Successful merges:
- #77765 (Add LLVM flags to limit DWARF version to 2 on BSD)
- #77788 (BTreeMap: fix gdb provider on BTreeMap with ZST keys or values)
- #77795 (Codegen backend interface refactor)
- #77808 (Moved the main `impl` for FnCtxt to its own file.)
- #77817 (Switch rustdoc from `clean::Stability` to `rustc_attr::Stability`)
- #77829 (bootstrap: only use compiler-builtins-c if they exist)
- #77870 (Use intra-doc links for links to module-level docs)
- #77897 (Move `Strip` into a separate rustdoc pass)
Failed merges:
- #77879 (Provide better documentation and help messages for x.py setup)
- #77902 (Include aarch64-pc-windows-msvc in the dist manifests)
r? `@ghost`
bootstrap: only use compiler-builtins-c if they exist
The assignment of `features` above was added in rust-lang#60981, but
never used. Presumably the intent was to replace the string literal here
with it.
While I'm in the area, `compiler_builtins_c_feature` doesn't need to be
a `String`.
I'm not entirely sure of a great way to locally test this -- `./x.py test`
passed on my machine, but 🤷♂️.
r? @alexcrichton
Switch rustdoc from `clean::Stability` to `rustc_attr::Stability`
This gives greater type safety and is less work to maintain on the rustdoc end. It also makes rustdoc more consistent with rustc.
Noticed this while working on https://github.com/rust-lang/rust/issues/76998.
- Remove `clean::Stability` in favor of `rustc_attr::Stability`
- Remove `impl Clean for Stability`; it's no longer necessary
r? @GuillaumeGomez
cc @petrochenkov
Codegen backend interface refactor
This moves several things away from the codegen backend to rustc_interface. There are a few behavioral changes where previously the incremental cache (incorrectly) wouldn't get finalized, but now it does. See the individual commit messages.
BTreeMap: fix gdb provider on BTreeMap with ZST keys or values
Avoid error when gdb is asked to inspect a BTreeMap or BTreeSet with a zero-sized type as key or value. And clean up.
r? @Mark-Simulacrum
Refactor AST pretty-printing to allow skipping insertion of extra parens
Fixes#75734
Makes progress towards #43081
Unblocks PR #76130
When pretty-printing an AST node, we may insert additional parenthesis
to ensure that precedence is properly preserved in code we output.
However, the proc macro implementation relies on comparing a
pretty-printed AST node to the captured `TokenStream`. Inserting extra
parenthesis changes the structure of the reparsed `TokenStream`, making
the comparison fail.
This PR refactors the AST pretty-printing code to allow skipping the
insertion of additional parenthesis. Several freestanding methods are
moved to trait methods on `PrintState`, which keep track of an internal
`insert_extra_parens` flag. This flag is normally `true`, but we expose
a public method which allows pretty-printing a nonterminal with
`insert_extra_parens = false`.
To avoid changing the public interface of `rustc_ast_pretty`, the
freestanding `_to_string` methods are changed to delegate to a
newly-crated `State`. The main pretty-printing code is moved to a new
`state` module to ensure that it does not accidentally call any of these
public helper functions (instead, the internal functions with the same
name should be used).
bootstrap: set correct path for the build-manifest binary
This changes the path of the binary inside the tarball to be:
```
build-manifest-{release}-{target}/build-manifest/bin/build-manifest
```
...instead of:
```
build-manifest-{release}-{target}/build-manifest/bin/build-manifest/build-manifest
```
r? @Mark-Simulacrum
