[Syntax] Implement auto trait syntax
Implements `auto trait Send {}` as a substitute for `trait Send {} impl Send for .. {}`.
See the [internals thread](https://internals.rust-lang.org/t/pre-rfc-renaming-oibits-and-changing-their-declaration-syntax/3086) for motivation. Part of #13231.
The first commit is just a rename moving from "default trait" to "auto trait". The rest is parser->AST->HIR work and making it the same as the current syntax for everything below HIR. It's under the `optin_builtin_traits` feature gate.
When can we remove the old syntax? Do we need to wait for a new `stage0`? We also need to formally decide for the new form (even if the keyword is not settled yet).
Observations:
- If you `auto trait Auto {}` and then `impl Auto for .. {}` that's accepted even if it's redundant.
- The new syntax is simpler internally which will allow for a net removal of code, for example well-formedness checks are effectively moved to the parser.
- Rustfmt and clippy are broken, need to fix those.
- Rustdoc just ignores it for now.
ping @petrochenkov @nikomatsakis
DefaultImpl is a highly confusing name for what we now call auto impls,
as in `impl Send for ..`. The name auto impl is not formally decided
but for sanity anything is better than `DefaultImpl` which refers
neither to `default impl` nor to `impl Default`.
`unreachable-pub` lint (as authorized by RFC 2126)
To whom it may concern:
RFC 2126 commissions the creation of a lint for `pub` items that are not visible from crate root (#45521). We understand (but seek confirmation from more knowledgable compiler elders) that this can be implemented by linting HIR items that are _not_ ~~`cx.access_levels.is_exported`~~ `cx.access_levels.is_reachable` but have a `vis` (-ibility) field of `hir::Visibility::Public`.
The lint, tentatively called ~~`unexported-pub`~~ `unreachable-pub` (with the understanding that much could be written on the merits of various names, as it is said of the colors of bicycle-sheds), suggests `crate` as a replacement for `pub` if the `crate_visibility_modifier` feature is enabled (see #45388), and `pub(crate)` otherwise. We also use help messaging to suggest the other potential fix of exporting the item; feedback is desired as to whether this may be confusing or could be worded better.
As a preview of what respecting the proposed lint would look like (and to generate confirmatory evidence that this implementation doesn't issue false positives), ~~we take its suggestions for `libcore`~~ (save one, which is deferred to another pull request because it brings up an unrelated technical matter). I remain your obedient servant.
r? @petrochenkov
typeck: suggest use of match_default_bindings feature
Fixes#45383.
Updates #42640.
r? @nikomatsakis
cc @tschottdorf
This needs a UI test, but thought I'd get some early feedback.
Improve display of error E0308
Ref. Forgetting to call a variant constructor causes a confusing error message #35241.
This PR modifies [`note_type_err`](b7041bfab3/src/librustc/infer/error_reporting/mod.rs (L669-L674)) to display a `help` message when a `TyFnPtr` or `TyFnDef` are found and the return type, of the function or function pointer, is the same as the type that is expected.
The output of compiling
```rust
struct Foo(u32);
fn test() -> Foo { Foo }
fn main() {}
```
is now
```bash
$ rustc src/test/ui/issue-35241.rs
error[E0308]: mismatched types
--> src/test/ui/issue-35241.rs:13:20
|
13 | fn test() -> Foo { Foo }
| --- ^^^ expected struct `Foo`, found fn item
| |
| expected `Foo` because of return type
|
= help: did you mean `Foo { /* fields */ }`?
= note: expected type `Foo`
found type `fn(u32) -> Foo {Foo::{{constructor}}}`
error: aborting due to previous error
```
enable non-lexical lifetimes in the MIR borrow checker
This PR, joint work with @spastorino, fills out the NLL infrastructure and integrates it with the borrow checker. **Don't get too excited:** it includes still a number of hacks (the subtyping code is particularly hacky). However, it *does* kinda' work. =)
The final commit demonstrates this by including a test that -- with both the AST borrowck and MIR borrowck -- reports an error by default. But if you pass `-Znll`, you only get an error from the AST borrowck, demonstrating that the integration succeeds:
```
struct MyStruct {
field: String
}
fn main() {
let mut my_struct = MyStruct { field: format!("Hello") };
let value = &my_struct.field;
if value.is_empty() {
my_struct.field.push_str("Hello, world!");
//~^ ERROR cannot borrow (Ast)
}
}
```
incr.comp.: Implement compiler diagnostic persistence.
This PR implements storing and loading diagnostics that the compiler generates and thus allows for emitting warnings during incremental compilation without actually re-evaluating the thing the warning originally came from. It also lays some groundwork for storing and loading type information and MIR in the incr. comp. cache.
~~It is still work in progress:~~
- ~~There's still some documentation to be added.~~
- ~~The way anonymous queries are handled might lead to duplicated emissions of warnings. Not sure if there is a better way or how frequent such duplication would be in practice.~~
Diagnostic message duplication is addressed separately in #45519.
r? @nikomatsakis
Suggest renaming import if names clash
Closes https://github.com/rust-lang/rust/issues/32354.
The output for the example in the issue looks like this:
```
~/p/local-rust-dev-testing ❯❯❯ cargo +local-s1 build
Compiling local-rust-dev-testing v0.1.0 (file:///home/cldfire/programming_projects/local-rust-dev-testing)
error[E0252]: the name `ConstructorExtension` is defined multiple times
--> src/main.rs:49:5
|
48 | use extension1::ConstructorExtension;
| -------------------------------- previous import of the trait `ConstructorExtension` here
49 | use extension2::ConstructorExtension;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ConstructorExtension` reimported here
|
= note: `ConstructorExtension` must be defined only once in the type namespace of this module
help: You can use `as` to change the binding name of the import
|
49 | use extension2::ConstructorExtension as OtherConstructorExtension;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
```
This is my first PR that touches the compiler in any way, so if there's something else I need to do here (e.g. add a test), please let me know :).
edit and fix bad spacing of inner-attribute-not-allowed note
This multiline string literal was missing a backslash, leaving an awkward
newline and 35 spaces in the middle of the message.
But while we're here, the existing message seems kind of long in comparison to
similar notes: to cut it down, we excise the mentions of doc comments, which
seems sensible because we know that this erroneous attribute is not a doc
comment (notice the `is_sugared_doc: false` at the end of the function; if it
had been a doc comment, that error would get set in the `token::DocComment`
match branch of `parse_outer_attributes`).
The macro now takes a format string. It no longer defaults to using the
type name. Didn't seem worth going through contortions to maintain. I
also changed most of the debug formats to be `foo[N]` instead of `fooN`.
incr.comp.: Fix two problems with HIR hashing.
Fixes https://github.com/rust-lang/rust/issues/45469.
This PR fixes two small problems:
* Overflow checks are always enabled in a constant context, so we need to hash spans of potentially overflowing operations. (Eventually I'd like to handle spans differently so we don't have to make HIR hashing know so much about things like this.)
* The HIR map collector had a bug where it would assign the `DepNode::Hir` instead of the corresponding `DepNode::HirBody` in some nested contexts.
r? @nikomatsakis
This multiline string literal was missing a backslash, leaving an awkward
newline and 35 spaces in the middle of the message.
But while we're here, the existing message seems kind of long in comparison to
similar notes: to cut it down, we excise the mentions of doc comments, which
seems sensible because we know that this erroneous attribute is not a doc
comment (notice the `is_sugared_doc: false` at the end of the function; if it
had been a doc comment, that error would get set in the `token::DocComment`
match branch of `parse_outer_attributes`).
Fix duplicate display of error E0502
Ref. Repeated "mutable/immutable borrow" error messages #42106.
This PR modifies the return type of [`report_error_if_loan_conflicts_with_restriction`](0f0f5db465/src/librustc_borrowck/borrowck/check_loans.rs (L398-L403)) so the result can be checked in [`report_error_if_loans_conflict`](0f0f5db465/src/librustc_borrowck/borrowck/check_loans.rs (L377-L396)). This is done to prevent displaying a duplicate of the error message E0502 which is referenced in #42106.
The output of compiling:
```rust
fn do_something<T>(collection: &mut Vec<T>) {
let _a = &collection;
collection.swap(1, 2);
}
fn main() {}
```
is now
```bash
$ rustc src/test/compile-fail/issue-42106.rs
error[E0502]: cannot borrow `*collection` as mutable because `collection` is also borrowed as immutable
--> src/test/compile-fail/issue-42106.rs:13:5
|
12 | let _a = &collection;
| ---------- immutable borrow occurs here
13 | collection.swap(1, 2);
| ^^^^^^^^^^ mutable borrow occurs here
14 | }
| - immutable borrow ends here
error: aborting due to 2 previous errors
```
r? @estebank
