Don't report link-self-contained not being supported if it's turned off.

[yshui]

No description provided.

[rustbot]

Some changes occurred in compiler/rustc_codegen_ssa

cc @WaffleLapkin

[rustbot]

r? @wesleywiser

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[wesleywiser]

Change looks good, can we get a test added that covers showing and hiding this error message?

View changes since this review

[petrochenkov]

What is the motivation?
This is a "defensive" error that is reported while design and implementation of the feature is incomplete.
E.g. currently, IIRC, link-self-contained=false will not make shipped rust-lld unavailable on many targets, which it should ideally do.

[yshui]

E.g. currently, IIRC, link-self-contained=false will not make shipped rust-lld unavailable on many targets

Wait, on some targets, even with link-self-contained=n, bundled rust-lld is still used? That can't be, right?

    if self_contained {
        LinkSelfContainedComponents::all()
    } else {
        LinkSelfContainedComponents::empty()
    }

[petrochenkov]

I don't remember the details, need to check, but IIRC self_contained_components are just not inspected when they should on some targets, regardless of what they are set to.
So I'd rather not stabilize this option on more targets unless there's some specific motivation and audit.