shrinking the deprecated method span

[Rustin170506]

close #84637

[rust-highfive]

r? @estebank

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[Rustin170506]

I don't know if passing method span is a good solution😆

[estebank]

I'm happy with the changes, and it'd be fine to pass in a new param, but can't we use the existing Span parameter?

[estebank]

What happens if you change this and the change below to pass method_name.span on the already existing span parameter?

[Rustin170506]

Will get an error:

error[E0658]: use of unstable library feature 'fmt_internals': internal to format_args!
   --> /Users/rustin/ClionProjects/rust/library/core/src/macros/mod.rs:473:49
    |
473 |     ($dst:expr, $($arg:tt)*) => ($dst.write_fmt($crate::format_args!($($arg)*)))
    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(fmt_internals)]` to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.
error: could not compile `rustc-demangle`

[Rustin170506]

rust/compiler/rustc_span/src/lib.rs

Line 512 in d6d0283

pub fn allows_unstable(&self, feature: Symbol) -> bool {

It looks like this is because allow_internal_unstable is not recognized when we use method_span.

[estebank]

@bors r+

[bors]

📌 Commit 7c5bc20 has been approved by estebank