Print version diff for rust and cargo since last rustup.sh invocaction

[jakerr]

I've been using this patch on my local rustup.sh for sometime and quite like it as a way to see what has changed since my last update.

The prevailing style in this file seems to be 8 space indent in condition bodies, 4 elsewhere.
Though I'm unfamiliar with that style I tried to match it.

Also I'm no bash guru so please give a review before accepting 😅

The output looks like this:

... 

install: verifying installed binaries are executable

    Rust is ready to roll.

    Went from version:
    rustc 0.13.0-nightly (1652a1f2c 2014-10-28 22:11:56 +0000)
    to
    rustc 0.13.0-nightly (15dd90b64 2014-10-30 00:27:02 +0000)
    See diff here: https://github.com/rust-lang/rust/compare/1652a1f2c...15dd90b64

...

install: verifying installed binaries are executable

    Cargo is ready to roll.

    Went from version:
    cargo 0.0.1-pre-nightly (947a62b 2014-10-28 19:59:49 +0000)
    to
    cargo 0.0.1-pre-nightly (041d14e 2014-10-29 19:32:55 +0000)
    See diff here: https://github.com/rust-lang/cargo/compare/947a62b...041d14e

[ghost]

I think the "Went from version:" bit is certainly useful, however, I am not sure about the diff URL. For casual users of rustc I wouldn't expect the diff between two versions of the compiler/package manager to be of much use. I also think "Rust is ready to roll." should follow everything else.

[brson]

Seems like a useful feature, but I think I agree about the diff link - it's pretty specialized.

The order of installation is pre-existing and I don't think we need to change it here, but yes that is a pet peeve of mine too. It's intended to be fixed as part of #16456 but we could do a follow up to fix it in rustup.sh. The only reason I haven't done it before is that it's conceptually strange to for cargo (which is unusable without rustc) to be installed before rustc.

[brson]

Note that even if this lands it has to be deployed manually.

[brson]

Oh, I also might prefer to have the version notice before the 'ready to roll' message. Ideally - as long as we're being cute - I prefer 'Rust is ready to roll' be the last thing printed. Get's you pumped up for some Rust!

[brson]

In that case, these version messages would need to be added to install.sh in this repo and cargo, which seems like the appropriate place for them anyway.

[brson]

Sorry for all the spam. If these messages go into install.sh that adds new requirements to the future combined installer. Haven't thought about the impact.

cc @alexcrichton

[alexcrichton]

I agree with basically all of @brson's comments, install.sh seems like a good place for this rather than rustup.sh.

[jakerr]

Thanks for the feedback. I'm happy to move this into the install scripts if people want it.

Re: the comment on the diff URL potentially being too specialized and not useful for casual rust users I'd encourage you to actually visit one of the URLs if you haven't: 1652a1f...15dd90b
It's not a simple git-diff but actually a list of all of the commits that have landed since your last upgrade which can be a great help for understanding why your code stopped compiling after an upgrade. Obviously less useful once we have stability post 1.0.

Can I get a few more comments as to whether or not we should show a github diff URL?

[ghost]

@jakerr Indeed, I should have clicked on the link! As you pointed out it is more than a diff but I still think it is rather unapproachable to most present and future users of Rust. It is certainly not easy to navigate that list to learn what had changed in the language in between two versions of the compiler. If we continuously maintained RELEASES.md on a commit-to-commit basis then perhaps that would be a useful resource to link to.

[jakerr]

@jakub- No worries! That's a fair assessment. I find the github diff link very useful, but it's probably because I follow the project quite closely so a quick scan of the commits is enough; but I think you're right and I'm probably not a typical user.