In [137653], the lang and libs-API teams did a joint FCP to deprecate
and eventually remove the long-unstable `concat_idents!` macro. The
deprecation is landing in 1.88, so do the removal here (target version
1.90).
This macro has been superseded by the more recent `${concat(...)}`
metavariable expression language feature, which avoids some of the
limitations of `concat_idents!`. The metavar expression is unstably
available under the [`macro_metavar_expr_concat`] feature.
History is mildly interesting here: `concat_idents!` goes back to 2011
when it was introduced with 513276e595 ("Add #concat_idents[] and
about the same:
let asdf_fdsa = "<.<";
assert(#concat_idents[asd,f_f,dsa] == "<.<");
assert(#ident_to_str[use_mention_distinction]
== "use_mention_distinction");
(That test existed from introduction until its removal here.)
Closes: https://www.github.com/rust-lang/rust/issues/29599
[137653]: https://www.github.com/rust-lang/rust/pull/137653
[`macro_metavar_expr_concat`]: https://www.github.com/rust-lang/rust/issues/124225
- Either explicitly annotate `let x: () = expr;` where `x` has unit
type, or remove the unit binding to leave only `expr;` instead.
- Fix disjoint-capture-in-same-closure test
