75a9be609e
`concat_idents` has been around unstably for a long time, but there is
now a better (but still unstable) way to join identifiers using
`${concat(...)}` syntax with `macro_metavar_expr_concat`. This resolves
a lot of the problems with `concat_idents` and is on a better track
toward stabilization, so there is no need to keep both versions around.
`concat_idents!` still has a lot of use in the ecosystem so deprecate it
before removing, as discussed in [1].
Link: https://github.com/rust-lang/rust/issues/124225
[1]: https://rust-lang.zulipchat.com/#narrow/channel/219381-t-libs/topic/Removing.20.60concat_idents.60
10 lines
300 B
Rust
10 lines
300 B
Rust
#![feature(concat_idents)]
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#![expect(deprecated)] // concat_idents is deprecated
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#[derive(Debug)]
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struct Baz<T>(
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concat_idents!(Foo, Bar) //~ ERROR `derive` cannot be used on items with type macros
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//~^ ERROR cannot find type `FooBar` in this scope
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);
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fn main() {}
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