Compiler optimization suggestion - Iter<String>.collect::<Vec<String>>().join("")

[yoav-lavi]

Hi,

I've opened this issue for clippy: rust-lang/rust-clippy#8570 wherein a collect::<Vec<String>>().join("") operation on an Iter<String> can be expressed as collect::<String>() which is more performant.

I wanted to put this here as well as I think this may be something that can also be optimized by the compiler (by replacing the former with the latter) since the output should always be equivalent and the latter option is more performant.

See cases of this happening in the wild here (GitHub CS Beta) or here (Sourcegraph)

I'm learning Rust so please let me know if I'm missing something, thank you!

[leonardo-m]

I wanted to put this here as well as I think this may be something that can also be optimized by the compiler

I think rustc creators don't like (or don't have time) to add similar special cased optimizations. In past years I have suggested many times spot optimizations for rustc and I think they were never implemented.

[blyxyas]

@rustbot label: +S-inactive

[blyxyas]

A lint for clippy is already merged (rust-lang/rust-clippy#8579) I think this issue can be closed as has had no updates for 9 months and will probably not be re-implemented in the Rust compiler, as it is already in Clippy.

[yoav-lavi]

For anyone seeing this in the future - Please take a look at the comments here: rust-lang/rust-clippy#8579
This change being more performant depends on the target arch