Re: [PATCH 0/3] rust: pin-init: provide better span for diagnostics

["Gary Guo" <gary@garyguo.net>]

On Wed Sep 16, 2026 at 1:11 PM BST, Gary Guo wrote:
> When initializing a field, pin-init first projects the full slot to a slot
> of the field, then initialize it by invoking a method. Currently the span
> location is not explicitly set, so the error message points to the full
> macro invocation.
>
> Improve it by provide a span, so Rust will point to the specific fields
> causing the error when type check fails.
>
> Old error message:
>
>     error[E0308]: mismatched types
>      --> tests/ui/compile-fail/init/field_value_wrong_type.rs:8:28
>       |
>     8 |     let _ = init!(Foo { a: () });
>       |             ---------------^^---
>       |             |              |
>       |             |              expected `usize`, found `()`
>       |             arguments to this method are incorrect
>
> New error message:
>
>     error[E0308]: mismatched types
>      --> tests/ui/compile-fail/init/field_value_wrong_type.rs:8:28
>       |
>     8 |     let _ = init!(Foo { a: () });
>       |                         ---^^
>       |                         |  |
>       |                         |  expected `usize`, found `()`
>       |                         arguments to this method are incorrect
>
> ---
> Gary Guo (4):
>       rust: pin-init: internal: init: emit `slot` using mixed site hygiene
>       rust: pin-init: internal: init: use `slot` identifier directly with mixed site
>       rust: pin-init: internal: init: provide span for slot projection
>       rust: pin-init: internal: use span of Index for generated identifiers

Applied to pin-init-next.

Best,
Gary