opt-dist: explicitly pass --set build.metrics=true while running build

[ognevny]

at first it's not obvious that build.metrics should be enabled to use opt-dist which will lead to confusion. probably it's better to add a good error message which instructs to set this option manually

edit: are there more places which need such change?

[rustbot]

r? @Kobzol

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[rustbot]

Some changes occurred in src/tools/opt-dist

cc @Kobzol

[Kobzol]

Hi, if I understand the problem correctly, you are trying to use opt-dist manually (outside our CI) wit ha config that doesn't enable build metrics, and opt-dist breaks because it expects that metrics are enabled?

[ognevny]

yes, I use opt-dist with opt-dist local. probably I hadn't searched properly, but I didn't find any kind of manual on using it

[Kobzol]

It's slightly documented here, but it's really best effort, it's mostly designed for our internal CI usage, and potentially for distro people who are feeling courageous :)

You could fix the metrics problem by adding the flag in Bootstrap::build and also Bootstrap::dist, but wouldn't it be easier to simply create a config with build.metrics = true? We can document that this is required in the rustc-dev-guide.

[ognevny]

yeah, documenting seems a better option in this case. I'm just "playing" with opt-dist as I try to compile Rust with PGO in msys2 :)

[Kobzol]

You can modify the link that I posted directly in this repo (src/doc/rustc-dev-guide). Would you like to do it in this PR?

[ognevny]

thanks. I'll let you to change the docs, so it will be made prettier faster (than processing through multiple reviews 😄). feel free to close this PR

[Kobzol]

Well if you did the change, I could approve it, which probably makes it faster, because if I make the change, someone else will have to approve xD But it doesn't really matter. Sent #139691.