Tracking issue: edition manifest changes

[nrc]

• - rename rls and rustfmt to not include -preview
• - add profiles

cc @alexcrichton

[alexcrichton]

So nowadays I'm sort of terrified about doing anything with rustup, so I've attempted to run this through its paces to make sure that if we deploy this change whether it will actually work. Unfortunately it looks like it doesn't work?

I played around with our dev artifacts, and I was specifically applying a few changes for an updated manifest:

• All instances of rls-preview were replaced with rls (same for rustfmt
• This section was added to the end:

[rename.rls-preview]
to = 'rls'
# ... same for rustfmt 

If I installed a previous compiler with rls-preview then updating the compiler to this new manifest simply removed the rls-preview. Additionally rustup component add rls-preview would fail on the new manifest saying "component not found".

I think both of these aspects means there's bugs in rustup's handling of [rename] so we won't be able to do this by the time of the edition :(

[nrc]

If I installed a previous compiler with rls-preview then updating the compiler to this new manifest simply removed the rls-preview

I think you would need to have rls rather than rls-preview available to download too (I'd expect an error about this, but perhaps it is swallowed because rustup thinks it is a temporarily missing component?)

Additionally rustup component add rls-preview would fail on the new manifest saying "component not found".

I think this was never implemented

[alexcrichton]

In the new manifests though the rls-preview component didn't exist and only rls existed, but rustup didn't do the transition from rls-preview to rls automatically. I thought it would though?

[nrc]

rustup didn't do the transition from rls-preview to rls automatically

I'm not exactly sure what this means.

What happens is that if you have rls-preview installed, then rustup removes the rls-preview component and adds the rls component. But I think that if the rls component is not available, then it will only be able to remove the rls-preview one without adding the new one.

[alexcrichton]

@nrc the behavior I was seeing was that the rls component was available and listed in the manifest as available, but rustup didn't install the renamed component it just uninstalled the previous one. I may have tested a wrong manifest though!

[alexcrichton]

Updated strategy:

• We will add a "rename" of rustfmt to rustfmt-preview (and clippy)
• We're updating rustup to accept rustup component add rls. It doesn't accept that today, but it's specified in the manifest [rename] section
• We're not landing profiles before the edition

Those two will get us over the hump for the edition. The end state is that rustup component add rls will work, although it'll probably print that it's installing the "rls-preview" component. We'll fix that UI bug once rust-lang/rustup#1546 is fixed