It was pointed out in review that the glob-exported
underscore-suffixed convention for `Spanned` HIR nodes is no longer
preferred: see February 2016's #31487 for AST's migration away from
this style towards properly namespaced NodeKind enums.
This concerns #51968.
There are at least a couple (and plausibly even three) diagnostics that
could use the spans of visibility modifiers in order to be reliably
correct (rather than hacking and munging surrounding spans to try to
infer where the visibility keyword must have been).
We follow the naming convention established by the other `Spanned` HIR
nodes: the "outer" type alias gets the "prime" node-type name, the
"inner" enum gets the name suffixed with an underscore, and the variant
names are prefixed with the prime name and `pub use` exported from here
(from HIR).
Thanks to veteran reviewer Vadim Petrochenkov for suggesting this
uniform approach. (A previous draft, based on the reasoning that
`Visibility::Inherited` should not have a span, tried to hack in a named
`span` field on `Visibility::Restricted` and a positional field on
`Public` and `Crate`. This was ... not so uniform.)
Namely: labels, type parameters, bindings in patterns, parameter names in functions without body.
All of these do not need hygiene after lowering to HIR, only span locations.
This is gated on edition 2018 & the `async_await` feature gate.
The parser will accept `async fn` and `async unsafe fn` as fn
items. Along the same lines as `const fn`, only `async unsafe fn`
is permitted, not `unsafe async fn`.The parser will not accept
`async` functions as trait methods.
To do a little code clean up, four fields of the function type
struct have been merged into the new `FnHeader` struct: constness,
asyncness, unsafety, and ABI.
Also, a small bug in HIR printing is fixed: it previously printed
`const unsafe fn` as `unsafe const fn`, which is grammatically
incorrect.
Add existential type definitions
Note: this does not allow creating named existential types, it just desugars `impl Trait` to a less (but still very) hacky version of actual `existential type` items.
r? @nikomatsakis
Add lint for intra link resolution failure
This PR is almost done, just remains this note:
```
note: requested on the command line with `-W intra-link-resolution-failure`
```
I have no idea why my lint is considered as being passed through command line and wasn't able to find where it was set. If anyone has an idea, it'd be very helpful!
cc @QuietMisdreavus
Use spans pointing at the inside of a rustdoc attribute
Follow up to #51111.
Point to the link in a rustdoc attribute where intralink resolution failed, instead of the full rustdoc attribute's span.
r? @GuillaumeGomez cc @kennytm
