When encountering an unmet trait bound, point at local type that doesn't implement the trait:
```
error[E0277]: the trait bound `Bar<T>: Foo` is not satisfied
--> $DIR/issue-64855.rs:9:19
|
LL | pub struct Bar<T>(<Self as Foo>::Type) where Self: ;
| ^^^^^^^^^^^^^^^^^^^ unsatisfied trait bound
|
help: the trait `Foo` is not implemented for `Bar<T>`
--> $DIR/issue-64855.rs:9:1
|
LL | pub struct Bar<T>(<Self as Foo>::Type) where Self: ;
| ^^^^^^^^^^^^^^^^^
```
Refactor rustc_on_unimplemented's filter parser
Followup to https://github.com/rust-lang/rust/pull/139091; I plan on moving most of this code into `rustc_attr_parsing` at some point, but want to land this separately first.
I have taken care to preserve the original behavior as much as I could:
- All but one of the new error variants are replacements for the ones originally emitted by the cfg parsing machinery; so these errors are not "new".
- the `InvalidFlag` variant is new, this PR turns this (from being ignored and silently doing nothing) into an error:
```rust
#[rustc_on_unimplemented(on(something, message = "y"))]
//~^ ERROR invalid boolean flag
//~^^ NOTE expected one of `crate_local`, `direct` or `from_desugaring`, not `something`
trait InvalidFlag {}
```
This does not occur anywhere except in this test. I couldn't find a way that I liked to keep allowing this or to do nothing, erroring was the cleanest solution.
- There are a bunch of FIXME throughout this and the previous PR, I plan on addressing those in follow up prs..
Finally, this gets rid of the "longest" dependency in rustc:
```
error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
--> $DIR/attempted-access-non-fatal.rs:7:15
|
LL | let _ = 2.l;
| ^
|
help: if intended to be a floating point literal, consider adding a `0` after the period and a `f64` suffix
|
LL - let _ = 2.l;
LL + let _ = 2.0f64;
|
```
Suggest creating unary tuples when types don't match a trait
When you want to have a variadic function, a common workaround to implement this is to create a trait and then implement that trait for various tuples. For example in `pyo3` there exists
```rust
/// Calls the object with only positional arguments.
pub fn call1(&self, args: impl IntoPy<Py<PyTuple>>) -> PyResult<&PyAny> {
...
}
```
with various impls like
```rust
impl<A: IntoPy<PyObject> IntoPy<Py<PyAny>> for (A,)
impl<A: IntoPy<PyObject, B: IntoPy<PyObject> IntoPy<Py<PyAny>> for (A, B)
... etc
```
This means that if you want to call the method with a single item you have to create a unary tuple, like `(x,)`, rather than just `x`.
This PR implements a suggestion to do that, if applicable.
When a trait is not implemented for a type, but there *is* an `impl`
for another type or different trait params, we format the output to
use highlighting in the same way that E0308 does for types.
The logic accounts for 3 cases:
- When both the type and trait in the expected predicate and the candidate are different
- When only the types are different
- When only the trait generic params are different
For each case, we use slightly different formatting and wording.
Remove the "which is required by `{root_obligation}`" post-script in
"the trait `X` is not implemented for `Y`" explanation in E0277. This
information is already conveyed in the notes explaining requirements,
making it redundant while making the text (particularly in labels)
harder to read.
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
vs the prior
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`, which is required by `Option<NotCopy>: Copy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
Expand the primary span of E0277 when the immediate unmet bound is not what the user wrote:
```
error[E0277]: the trait bound `i32: Bar` is not satisfied
--> f100.rs:6:6
|
6 | <i32 as Foo>::foo();
| ^^^ the trait `Bar` is not implemented for `i32`, which is required by `i32: Foo`
|
help: this trait has no implementations, consider adding one
--> f100.rs:2:1
|
2 | trait Bar {}
| ^^^^^^^^^
note: required for `i32` to implement `Foo`
--> f100.rs:3:14
|
3 | impl<T: Bar> Foo for T {}
| --- ^^^ ^
| |
| unsatisfied trait bound introduced here
```
Fix#40120.
Change the implicit `Sized` `Obligation` `Span` for call expressions to
include the whole expression. This aids the existing deduplication
machinery to reduce the number of errors caused by a single unsized
expression.
