79630d4fdf
This commit starts to lay some groundwork for the stabilization of custom attribute invocations and general procedural macros. It applies a number of changes discussed on [internals] as well as a [recent issue][issue], namely: * The path used to specify a custom attribute must be of length one and cannot be a global path. This'll help future-proof us against any ambiguities and give us more time to settle the precise syntax. In the meantime though a bare identifier can be used and imported to invoke a custom attribute macro. A new feature gate, `proc_macro_path_invoc`, was added to gate multi-segment paths and absolute paths. * The set of items which can be annotated by a custom procedural attribute has been restricted. Statements, expressions, and modules are disallowed behind two new feature gates: `proc_macro_expr` and `proc_macro_mod`. * The input to procedural macro attributes has been restricted and adjusted. Today an invocation like `#[foo(bar)]` will receive `(bar)` as the input token stream, but after this PR it will only receive `bar` (the delimiters were removed). Invocations like `#[foo]` are still allowed and will be invoked in the same way as `#[foo()]`. This is a **breaking change** for all nightly users as the syntax coming in to procedural macros will be tweaked slightly. * Procedural macros (`foo!()` style) can only be expanded to item-like items by default. A separate feature gate, `proc_macro_non_items`, is required to expand to items like expressions, statements, etc. Closes #50038 [internals]: https://internals.rust-lang.org/t/help-stabilize-a-subset-of-macros-2-0/7252 [issue]: https://github.com/rust-lang/rust/issues/50038 |
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| .. | ||
| auxiliary | ||
| custom-derive | ||
| proc-macro | ||
| deprecated-derive.rs | ||
| deprecated-derive.stderr | ||
| lint-group-plugin.rs | ||
| lint-group-plugin.stderr | ||
| lint-plugin-cmdline-allow.rs | ||
| lint-plugin-cmdline-allow.stderr | ||
| lint-plugin-cmdline-load.rs | ||
| lint-plugin-cmdline-load.stderr | ||
| lint-plugin-forbid-attrs.rs | ||
| lint-plugin-forbid-attrs.stderr | ||
| lint-plugin.rs | ||
| lint-plugin.stderr | ||
| resolve-error.rs | ||
| resolve-error.stderr | ||
| update-all-references.sh | ||
| update-references.sh | ||