Minor annoyances I with Rust didn’t have.
Directory layout.
We should have done directory-per-crate.
Collocating lib.rs and main.rs causes confusion.
On a similar note, tests and benches should be one crate by default, to save compile times
Complex Semver Requirements
Cargo.toml should support only "x.y.z" and "=x.y.z" requirements.
Things like < or ~ create ecosystem-wide problems.
Incomplete mod.rs transition.
De-facto, both foo/mod.rs and foo.rs are used today.
It would probably be better if only one way was allowed.
Nested imports.
We now allow use crate::{module::{item}}, which we used not to.
As a result, projects are split by the import style they use.
Seems better if we sticked with simple one-level nesting only.
Complex Visibility Rules
pub(crate) is a lot to type, pub(in …) doesn’t pull its weight, imports creating item is confusing and not useful.
It’d be better to have just pub with the meaning of pub(crate) and pub* for exporting across crate boundary.
Ranges
Ranges should be #[derive(Copy), with all fields public.
BinaryHeap
It should be called (and be) a MinHeap, with pop_min instead of pop.
Map
Maps and sets should assert in insert! that the element is new, and use
replace to let the user handle the old value.
Error/Err
TryFrom::Error and FromStr::Err are inconsistent.