Suggest `_` for missing generic arguments in turbofish by kornelski · Pull Reque...
source link: https://github.com/rust-lang/rust/pull/122651
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The compiler may suggest unusable generic type names for missing generic arguments in an expression context:
fn main() {
(0..1).collect::<Vec>()
}help: add missing generic argument
(0..1).collect::<Vec<T>>()
but T is not a valid name in this context, and this suggestion won't compile.
I've changed it to use _ inside method calls (turbofish), so it will suggest (0..1).collect::<Vec<_>>() which may compile.
It's possible that the suggested _ will be ambiguous, but there is very extensive E0283 that will help resolve that, which is more helpful than a basic "cannot find type T in this scope" users would get otherwise.
Out of caution to limit scope of the change I've limited it to just turbofish, but I suspect _ could be the better choice in more cases. Perhaps in all expressions?
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