Make tier 3 musl targets link dynamically by default

[Gelbpunkt]

Since we don't build std for these and don't provide any support for them, these can trivially be changed to link dynamically by default.

[rustbot]

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[rustbot]

These commits modify compiler targets.
(See the Target Tier Policy.)

[jieyouxu]

Pinging target maintainers as a heads-up:

• mips64-unknown-linux-muslabi64: @Gelbpunkt
• hexagon-unknown-linux-musl: @androm3da
• powerpc64-unknown-linux-musl: @Gelbpunkt @famfo @neuschaefer
• powerpc-unknown-linux-musl: no platform support page / no listed target maintainer
• powerpc-unknown-linux-muslspe: @BKPepe
• riscv32gc-unknown-linux-musl: no platform support page / no listed target maintainer
• s390x-unknown-linux-musl: @uweigand
• thumbv7neon-unknown-linux-musleabihf: no platform support page / no listed target maintainer

[Gelbpunkt]

Just FYI, the hexagon target already links dynamically by default, I just removed the explicit line there since the default musl target already links dynamically. So hexagon doesn't change behavior here :)

[androm3da]

Just FYI, the hexagon target already links dynamically by default, I just removed the explicit line there since the default musl target already links dynamically. So hexagon doesn't change behavior here :)

Thanks - LGTM.

[petrochenkov]

IIRC, there was an official decision to switch all musl targets to dynamically-linked-by-default, which didn't turn into an actual implementation.
It would be good to find it and link it from here.

[Gelbpunkt]

which didn't turn into an actual implementation.

It (partially) did, the base linux_musl target is dynamically linked now, so any new targets will be dynamically linked. Noone has taken onto the existing ones yet.

I'm working on implementing the lint that was proposed in the MCP as a step towards changing the tier 2 targets to be dynamically linked, but that lint isn't necessary to change the tier 3 targets like done in this PR.

The original MCP is rust-lang/compiler-team#422

[Gelbpunkt]

@jieyouxu hi there, it's been a week so I was wondering whether this could be merged?
Out of the affected targets, only 4 of them have maintainers listed, and all of them except powerpc-unknown-linux-muslspe have shown their agreement with this PR. The powerpc-unknown-linux-muslspe target currently is broken anyways (#138960), so I think there's nothing stopping this.

[jieyouxu]

IIRC, there was an official decision to switch all musl targets to dynamically-linked-by-default, which didn't turn into an actual implementation. It would be good to find it and link it from here.

I believe this was rust-lang/compiler-team#422.

[jieyouxu]

Judging from the thumb ups and explicit approvals, there is consensus in favor of this change from all pinged target maintainers. Since these targets are all Tier 3 and do not have pre-compiled std, we can make this change without too much hassle.

[jieyouxu]

Thanks! I'll tag this with relnotes just so users of these targets might have a chance to be aware of this change.
r? jieyouxu @bors r+ rollup

[bors]

📌 Commit effcd54 has been approved by jieyouxu

It is now in the queue for this repository.