2dba56033e
Add FCW for derive helper attributes that will conflict with built-in attributes
Adds a future-compatibility-warning deny-by-default lint that helps catch invalid derive helper attribute names early.
This issues the lint, saying that `ignore` helper will clash with the built-in `ignore` attribute.
```rust
#![crate_type = "proc-macro"]
#![deny(ambiguous_derive_helpers)]
use proc_macro::TokenStream;
#[proc_macro_derive(Trait, attributes(ignore))]
pub fn example(input: TokenStream) -> TokenStream {
TokenStream::new()
}
```
If you actually tried to use that `ignore` helper attribute, you won't be able to due to the ambiguity:
```rust
#[derive(Trait)]
struct Foo {
#[ignore]
field: (),
}
```
Produces:
```
error[E0659]: `ignore` is ambiguous
--> src/lib.rs:5:7
|
5 | #[ignore]
| ^^^^^^ ambiguous name
|
= note: ambiguous because of a name conflict with a builtin attribute
= note: `ignore` could refer to a built-in attribute
note: `ignore` could also refer to the derive helper attribute defined here
--> src/lib.rs:3:10
|
3 | #[derive(Trait)]
| ^^^^^
```
|
||
|---|---|---|
| .. | ||
| assembly-llvm | ||
| auxiliary | ||
| build-std/configurations | ||
| codegen-llvm | ||
| codegen-units | ||
| coverage | ||
| coverage-run-rustdoc | ||
| crashes | ||
| debuginfo | ||
| incremental | ||
| mir-opt | ||
| pretty | ||
| run-make | ||
| run-make-cargo | ||
| rustdoc-gui | ||
| rustdoc-html | ||
| rustdoc-js | ||
| rustdoc-js-std | ||
| rustdoc-json | ||
| rustdoc-ui | ||
| ui | ||
| ui-fulldeps | ||
| COMPILER_TESTS.md | ||