Messages in this thread | | | Date | Wed, 17 Apr 2024 16:06:36 +0100 | From | Gary Guo <> | Subject | Re: [PATCH] rust: init: change the generated name of guard variables |
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On Wed, 03 Apr 2024 22:09:49 +0000 Benno Lossin <benno.lossin@proton.me> wrote:
> On 03.04.24 23:20, Boqun Feng wrote: > > On Wed, Apr 03, 2024 at 07:43:37PM +0000, Benno Lossin wrote: > >> The initializers created by the `[try_][pin_]init!` macros utilize the > >> guard pattern to drop already initialized fields, when initialization > >> fails mid-way. These guards are generated to have the same name as the > >> field that they handle. To prevent namespacing issues when the field > > > > Do you have an example of this kind of issues? > > https://lore.kernel.org/rust-for-linux/1e8a2a1f-abbf-44ba-8344-705a9cbb1627@proton.me/ >
Here's the simplified example:
``` macro_rules! f { () => { let a = 1; let _: u32 = a; } }
const a: u64 = 1;
fn main() { f!(); } ```
The `a` in `f` have a different hygiene so normally it is scoped to the macro expansion and wouldn't escape. Interestingly a constant is still preferred despite the hygiene so constants escaped into the macro, leading to the error.
Would your change regress error message when `pin_init!` is used wrongly? Personally I would say this kind of error is niche enough (given the casing of constants and variables differ) that we probably don't really need to care. So if error message would be affected then we'd better off not making the change.
Best, Gary
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