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Attributes starting with rustc_ are supposed to be gated, but they are not always gated #62116
Description
Of course, the specific known built-in attributes like #[rustc_copy_clone_marker] are feature gated, but the rustc_* names are not reserved in general.
As a result, you can easily create a procedural macro attribute starting with rustc_.
As a result, introduction of a new built-in attribute is technically a breaking change even if the attribute starts with rustc_.
Q: Why is introduction of a new built-in attribute a breaking change.
A: Because built-in attributes will conflict with any other attributes in scope having the same name (see #53913 (comment) for some technical details).
Possible solutions:
- Reserve (feature gate) any attributes starting with
rustc_, including macros, run crater and see what happens. - Do nothing, this is not a big deal.
- Third party attribute names are unlikely to start with
rustc_. - We are going to add new non-
rustc_*built-in attributes anyway and go through the same technically breaking changes in process.
- Third party attribute names are unlikely to start with
Activity
Auto merge of #62133 - petrochenkov:norustc, r=<try>
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb
Rollup merge of rust-lang#62133 - petrochenkov:norustc, r=eddyb