(Meanwhile, a couple of parse-fail tests are moved to UI tests so that
the reader can see the new output, and an existing UI test is given a
more evocative name.)
Warn about ignored generic bounds in `for`
This adds a new lint to fix#42181. For consistency and to avoid code duplication, I also moved the existing "bounds in type aliases are ignored" here.
Questions to the reviewer:
* Is it okay to just remove a diagnostic error code like this? Should I instead keep the warning about type aliases where it is? The old code provided a detailed explanation of what's going on when asked, that information is now lost. On the other hand, `span_warn!` seems deprecated (after this patch, it has exactly one user left!).
* Did I miss any syntactic construct that can appear as `for` in the surface syntax? I covered function types (`for<'a> fn(...)`), generic traits (`for <'a> Fn(...)`, can appear both as bounds as as trait objects) and bounds (`for<'a> F: ...`).
* For the sake of backwards compatibility, this adds a warning, not an error. @nikomatsakis suggested an error in https://github.com/rust-lang/rust/issues/42181#issuecomment-306924389, but I feel that can only happen in a new epoch -- right?
Cc @eddyb
Programmers used to working in some other languages (such as Python or
Go) might expect to be able to destructure values with comma-separated
identifiers but no parentheses on the left side of an assignment.
Previously, the first name in such code would get parsed as a
single-indentifier pattern—recognizing, for example, the
`let a` in `let a, b = (1, 2);`—whereupon we would have a fatal syntax
error on seeing an unexpected comma rather than the expected semicolon
(all the way nearer to the end of `parse_full_stmt`).
Instead, let's look for that comma when parsing the pattern, and if we
see it, momentarily make-believe that we're parsing the remaining
elements in a tuple pattern, so that we can suggest wrapping it all in
parentheses. We need to do this in a separate wrapper method called on
the top-level pattern (or `|`-patterns) in a `let` statement, `for`
loop, `if`- or `while let` expression, or match arm rather than within
`parse_pat` itself, because `parse_pat` gets called recursively to parse
the sub-patterns within a tuple pattern.
Resolves#48492.
Also move the check for not having type parameters into ast_validation.
I was not sure what to do with compile-fail/issue-23046.rs: The issue looks like
maybe the bounds actually played a role in triggering the ICE, but that seems
unlikely given that the compiler seems to entirely ignore them. However, I
couldn't find a testcase without the bounds, so I figured the best I could do is
to just remove the bounds and make sure at least that keeps working.
When unnecessarily using a fat arrow after an if condition, suggest the
removal of it.
When finding an if statement with no block, point at the `if` keyword to
provide more context.
When finding:
```rust
match &Some(3) {
&None => 1
&Some(2) => { 3 }
_ => 2
}
```
provide the following diagnostic:
```
error: expected one of `,`, `.`, `?`, `}`, or an operator, found `=>`
--> $DIR/missing-comma-in-match.rs:15:18
|
X | &None => 1
| -- - help: missing comma
| |
| while parsing the match arm starting here
X | &Some(2) => { 3 }
| ^^ expected one of `,`, `.`, `?`, `}`, or an operator here
```
Fix span of visibility
This PR
1. adds a closing parenthesis to the span of `Visibility::Crate` (e.g. `pub(crate)`). The current span only covers `pub(crate`.
2. adds a `span` field to `Visibility::Restricted`. This span covers the entire visibility expression (e.g. `pub (in self)`). Currently all we can have is a span for `Path`.
This PR is motivated by the bug found in rustfmt (https://github.com/rust-lang-nursery/rustfmt/issues/2398).
The first change is a strict improvement IMHO. The second change may not be desirable, as it adds a field which is currently not used by the compiler.
When encountering a variadic argument in a function definition that
doesn't accept it, if immediately after there's a closing paren,
continue parsing as normal. Otherwise keep current behavior of emitting
error and stopping.
Add filtering options to `rustc_on_unimplemented`
- Add filtering options to `rustc_on_unimplemented` for local traits, filtering on `Self` and type arguments.
- Add a way to provide custom notes.
- Tweak binops text.
- Add filter to detect wether `Self` is local or belongs to another crate.
- Add filter to `Iterator` diagnostic for `&str`.
Partly addresses #44755 with a different syntax, as a first approach. Fixes#46216, fixes#37522, CC #34297, #46806.
- filter error on the evaluated value of `Self`
- filter error on the evaluated value of the type arguments
- add argument to include custom note in diagnostic
- allow the parser to parse `Self` when processing attributes
- add custom message to binops
syntax: Lower priority of `+` in `impl Trait`/`dyn Trait`
Now you have to write `Fn() -> (impl A + B)` instead of `Fn() -> impl A + B`, this is consistent with priority of `+` in trait objects (`Fn() -> A + B` means `(Fn() -> A) + B`).
To make this viable I changed the syntax to also permit `+` in return types in function declarations
```
fn f() -> dyn A + B { ... } // OK, don't have to write `-> (dyn A + B)`
// This is acceptable, because `dyn A + B` here is an isolated type and
// not part of a larger type with various operator priorities in play
// like `dyn A + B` in `Fn() -> dyn A + B` despite syntax similarities.
```
but you still have to use `-> (dyn A + B)` in function types and function-like trait object types (see this PR's tests for examples).
This can be a breaking change for code using `impl Trait` on nightly. The thing that is most likely to break is `&impl A + B`, it needs to be rewritten as `&(impl A + B)`.
cc https://github.com/rust-lang/rust/issues/34511https://github.com/rust-lang/rust/issues/44662https://github.com/rust-lang/rfcs/pull/438
Correctly format `extern crate` conflict resolution help
Closes#45799. Follow up to @Cldfire's #45820.
If the `extern` statement that will have a suggestion ends on a `;`, synthesize a new span that doesn't include it.
