Add --print host-triple to print host target triple

[Noratrieb]

People often parse -vV output to get to the host triple, which is annoying to do. It's easier to just get it directly.

I called it "host-triple" instead of "host" because it's clearer that it's just the target name. I'm open to different names, but I think this one is fine.

a quick GitHub search for '^host reveals many instances of people doing the parsing, for example:

https://github.com/japaric/xargo/blob/68e0ca57cd90837fe02f262f074182f9cfeb6227/README.md?plain=1#L369
https://github.com/taiki-e/setup-cross-toolchain-action/blob/0e38473b0c562d6db19a98d3ec20a80f7ac189ae/main.sh#L96
https://github.com/taiki-e/cargo-llvm-cov/blob/8a3553b86551eabf9c30c060b1f72a5bbccb98c6/README.md?plain=1#L625
https://github.com/SiliconLabs/cpc-nvm3/blob/43f3ec39709b30700ef7f39d91fa647974323bf1/do.sh#L35

needs a compiler FCP. I could also do an MCP but I think just an FCP here makes the most sense.

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[workingjubilee]

I would prefer host-tuple, so we don't have to stress about ontologies if the tuple happens to have 2 or 5. I am not the only one who has noticed this, and we also use tools that refer to them as target tuples. ( And as far as I can tell this would be the first stable API that explicitly names the concept beyond "target". )

[bjorn3]

a quick GitHub search for '^host reveals many instances of people doing the parsing, for example:

Cargo also does this.

[oli-obk]

@rfcbot merge

[rfcbot]

Team member @oli-obk has proposed to merge this. The next step is review by the rest of the tagged team members:

• @Aaron1011
• @cjgillot
• @compiler-errors
• @davidtwco
• @eddyb
• @estebank
• @jackh726
• @lcnr
• @matthewjasper
• @michaelwoerister
• @nagisa
• @oli-obk
• @petrochenkov
• @pnkfelix
• @wesleywiser

Concerns:

• triple vs tuple (Add --print host-triple to print host target triple #125579 (comment))

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[lcnr]

@rfcbot concern triple vs tuple

#125579 (comment)

[michaelwoerister]

As a data point, our existing documentation seem to call it "triple" pretty consistently:
https://doc.rust-lang.org/rustc/?search=triple
https://doc.rust-lang.org/cargo/index.html?search=triple
https://doc.rust-lang.org/reference/?search=triple

[apiraino]

So, should that be "tuple" or "triple"?

(trying to understand if the concern raised is still standing)

[lcnr]

I personally don't have a strong opinion here and would be open to rescind my concern

• tuple is more accurate as some targets don't use exactly 3 words
• triple is currently the used terminology, though it seems to only be internal

https://doc.rust-lang.org/rustc/platform-support/loongarch-linux.html?highlight=tuple#loongarch-unknown-linux- already uses tuple

@michaelwoerister @workingjubilee does one of you care strongly about either option? It is fairly arbitrary in the end (and its documentation should probably mention the alternative).

One simple way to resolve this might just be a vote on zulip and we pick whatever ends up on top as long as nobody feels very strongly about this: https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/.60--print.20host.5B-tuple.7C-triple.5D.60

[michaelwoerister]

I voted "don't care" on Zulip.

[oli-obk]

r? compiler

[davidtwco]

I don't think there's necessarily a strong consensus from the Zulip poll on terminology here, the team seems to have a slight preference towards host-tuple, do you want to change it to that @Noratrieb?