rust: pin-init: internal: init: improve diagnostics from field checks

Use span of the field name for generated alignment and field duplication
checks. This avoids pointing diagnostics to the full macro invocation, but
just the part of it going wrong.

Before the change:

    error[E0062]: field `0` specified more than once
     --> tests/ui/compile-fail/init/tuple_duplicate_field.rs:7:37
      |
    7 |     let _ = pin_init!(Tuple { 0: 1, 0: 2, 1: 3 });
      |             ------------------------^------------
      |             |                       |
      |             |                       used more than once
      |             first use of `0`

After the change:

    error[E0062]: field `0` specified more than once
     --> tests/ui/compile-fail/init/tuple_duplicate_field.rs:7:37
      |
    7 |     let _ = pin_init!(Tuple { 0: 1, 0: 2, 1: 3 });
      |                               -     ^ used more than once
      |                               |
      |                               first use of `0`

Link: https://patch.msgid.link/20260928-dev-pin-init-sync-v1-2-e591c8e9cf0e@garyguo.net
Signed-off-by: Gary Guo <gary@garyguo.net>

0 files changed, 0 insertions, 0 deletions