[steveklabnik]

Note that this is a sliiiightly modified SemVer: in SemVer, these three things would conflict. It would be strict SemVer if uno depended on ~>1.3, and dos on ~>1.4.

We hypothesize that this difference works better for AOT compiled languages. And since it's pre-1.0, it's all good. This is the 'we'll watch this closely and adjust' from the email: it might not be okay.

[ionforce]

Why would uno not work on 1.4?

[steveklabnik]

When you declare an x.y.z dependency, tools that use SemVer (like Bundler, which is the biggest influence on Cargo) assume x.y.(>z). So, a 1.4.12 dependency says "Anything greater than 1.4.12, but less than 1.5.0."

When you declare an x.y dependency, tools that use SemVer assumes x.(>y). So, a 1.4 dependency says "Anything greater than 1.4.anything, but less than 2.anything.anything".

This is assuming the ~> operator, if it was =, it would ONLY be 1.14.2, which is even more restrictive.

The project _should_ work, which is why Cargo is using this modified version of ~>.