> By specifying the exact version you require,
This is only half true. It comes in two steps: you specify a _kind_ of version that you require, like
foo = "^1.2.0"
and then, during the build step, it resolves all of the dependencies and their dependencies (etc) and writes the exact version out to a file. So you do end up with specific ones, but you won't neccesarily end up with multiple versions.This also matters because...
> maintainers may neglect the tedious task of keeping their projects' dependencies up-to-date,
You just run 'cargo update' and it will re-calculate that dependency graph, and re-write out the lock file. You're as up to date as you can be. Of course, if that fix is only available in a range outside you've specified, that's different.
That's the last time where I heard about this wonderful idea that vendoring everything is a solution, because versioning is hard: https://www.kickstarter.com/projects/2066438441/haunts-the-m...
I'll take the solution where I can send a PR to the maintainer with updated dependencies over this sort of thing any day.
I should also state I fall on the extreme end of the spectrum. My belief is that the moment you depend on upstream package X it is wholly your responsibility to track changes and adapt your code accordingly. I don't believe software versioning does anything but encourage poor security, performance and general fragmentation.
I believe that before pushing your changes to a remote repo, you locally check that everything is stable, meaning there is no dev branch or stable releases just one true master branch!
If you don't want the bleeding edge then don't 'git pull'. simple!
The world goes boom! exponential overload!
... at least it get's really frustrating after a while, twice the space, twice the compilation time. And you'll know at least one of the libs has bugs lurking in it that have been fixed elsewhere except in that lib:(
Subtle things in dynamic linking may break applications when dependency versions are changed.
Static linking lets you bundle whatever version is known to work, including the most up to date versions.
As you may be aware, there is limited support for versioning APIs using "go get" (Go's nearest equivalent of this). The developers of Go argue that the maintenance of your dependencies is your responsibility, and you should clone everything you need to your own environment. That gives you ultimate control, allowing you to pull and update them as you require, modify and bugfix as you see fit, and makes it hard, if not impossible, to end up relying on two packages with different versions.
If a project B depends on project A, then they must collaborate in some way to make sure that there are no breaking changes introduced between (minor) versions. If another project C also depends on A, then they must both use the same version of A if they are to be used together. The maintainers of A, B and C all have a duty to ensure that their code remains up-to-date and backwards compatible.
It seems that Rust values a different freedom. By specifying the exact version you require, there is no need to keep separate projects in sync. The flexibility comes at a cost; you may find you have different versions of many dependencies. Because they are not required to, maintainers may neglect the tedious task of keeping their projects' dependencies up-to-date, requiring bugfixes in multiple places in your own codebase.
Clearly, some of the smartest minds in our industry disagree what the best tradeoff is. It is interesting to see the range of opinion though.