from_iter_instead_of_collect feels like a blanket ban of the FromIterator trait

[Nemo157]

I tried this code:

Vec::from_iter(2..5)

I expected to see this happen: no warning

Instead, this happened:

warning: usage of `FromIterator::from_iter`
   --> src/lib.rs:219:1
    |
219 | Vec::from_iter(2..5);
    | ^^^^^^^^^^^^^^^^^^^^ help: use `.collect()` instead of `::from_iter()`: `(2..5).collect::<Vec<_>>()`
    |
    = note: `#[warn(clippy::from_iter_instead_of_collect)]` on by default
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#from_iter_instead_of_collect

The Vec::from_iter call is much more succinct and readable than .collect::<Vec<_>>(), and rust-lang/rfcs#3114 is currently in FCP-disposition-merge to add std::iter::FromIterator to the Rust 2021 prelude. Having Clippy recommend against using it seems to go against the decision there that it is a trait to be used directly.

I'm really not sure if there's some subset of this lint that would feel ok, there's maybe some sort of "collect here would be more readable", but defining heuristics to detect when to enable that seems complicated.

Meta

• cargo clippy -V: clippy 0.1.53 (42816d6 2021-04-24)

[djc]

Previously: #6550. Let's say it's not a coincidence that I got involved in the prelude changes. Given that the RFC has been accepted, I do think it's time to make this allow by default.

[camsteffen]

Congrats @djc on your success with appealing your case to the Supreme Court! 😉

I agree. This lint is founded on a style principle that is, well, going out of style.

[camsteffen]

I think it would be better to fix the lint to only include cases where turbofish is not needed. Moving to pedantic doesn't really solve the issue here.

[djc]

What semantics do you suggest exactly? The lint should only trigger if the full destination type can be inferred?

[camsteffen]

Right.