To me, the two major problems are:
- no namespaces
Someone uploads “serde2”? that’s blocked forever. Someone uploads a typo version of a popular package? Too bad for you, learn how to type.
- the github connection
If you want to contribute to crates.io you’re bound to github. No gitlab, codeberg, gitee, sourcehut, etc.
Not sure if there are any other problems, but those two seem like the biggest things and #1 is AFAIK not something they ever want to change + it would be difficult to as one would need a migration strategy.
Semver strings allows stuff like “version 2.5.x, but below 2.5.6”. Then cargo calculates the best solution for satisfying all dependency specifications from all packages using a single version (if possible).
Specifying a version in addition to the git branch doesn’t help there at all, because you still have to do it manually then.