macros 1.1: future proofing and cleanup #37198
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Looks good to me but I'm not 100% familiar with all the changes, so
r? @nrc
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| #![feature(proc_macro)] | ||
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| #[macro_use] | ||
| extern crate derive_a; | ||
| #[macro_use] | ||
| extern crate derive_a_2; //~ ERROR: cannot shadow existing derive mode `A` | ||
| extern crate derive_a; //~ ERROR `derive_a` has already been defined |
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Hm isn't this testing something else than before? Before it was preventing two #[proc_macro_derive(A)] was an error, but here it's erroring out on the extern crate annotations?
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Yeah, it used to test that a #[macro_use]-imported custom derive cannot shadow an existing #[macro_use]-imported custom derive.
This PR changes #[macro_use]-imported custom derives to have the same scope and shadowing restrictions as other #[macro_use]-imported macros, so it is no longer an error for an unexpanded #[macro_use] to import a shadowing custom derive (just as it is not an error today for ordinary unexpanded #[macro_use]s to shadow).
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(c.f. the second bullet point in the initial comment)
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@bors: r+ |
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📌 Commit aac6dca has been approved by |
…=nrc macros 1.1: future proofing and cleanup This PR - uses the macro namespace for custom derives (instead of a dedicated custom derive namespace), - relaxes the shadowing rules for `#[macro_use]`-imported custom derives to match the shadowing rules for ordinary `#[macro_use]`-imported macros, and - treats custom derive `extern crate`s like empty modules so that we can eventually allow, for example, `extern crate serde_derive; use serde_derive::Serialize;` backwards compatibly. r? @alexcrichton
…=nrc macros 1.1: future proofing and cleanup This PR - uses the macro namespace for custom derives (instead of a dedicated custom derive namespace), - relaxes the shadowing rules for `#[macro_use]`-imported custom derives to match the shadowing rules for ordinary `#[macro_use]`-imported macros, and - treats custom derive `extern crate`s like empty modules so that we can eventually allow, for example, `extern crate serde_derive; use serde_derive::Serialize;` backwards compatibly. r? @alexcrichton
This PR
#[macro_use]-imported custom derives to match the shadowing rules for ordinary#[macro_use]-imported macros, andextern crates like empty modules so that we can eventually allow, for example,extern crate serde_derive; use serde_derive::Serialize;backwards compatibly.r? @alexcrichton