…r=workingjubilee

Document That `f16` And `f128` Hardware Support is Limited

This adds a small paragraph to the recently added f16 and f128 types explaining that hardware support may be limited, and that performance may suffer as a result of that.

I mainly wrote this because I felt it may be useful to express in some form; as a launchpoint for readers of the documentation if they have issues with performance.

I tried to word the documentation in a way that doesn't create false assumptions (that f16/f128 is too slow to use, for instance), removing the software implementation part could mislead people to thinking that f16/f128 is only available on some platforms, not all, so I believe it is important to keep in.\
"not all *major* platforms" is specifically said so as to not be redundant, because not all platforms implement many things, but the average rustacean is probably going to be using x86_64 or aarch64 derived ISA's, which is who this documentation is targeted towards.

I'm not sure of the best way to word the documentation, or if it should even be added, but I feel like it may be useful to have (potentially in a reworded way, I'm not very confident in the current wording and cannot decide if that is because it is too vague to be useful or too specific to be generally correct).

Rollup of 7 pull requests

Successful merges:

 - rust-lang#122253 (Support Result<T, E> across FFI when niche optimization can be used)
 - rust-lang#123892 (Document That `f16` And `f128` Hardware Support is Limited)
 - rust-lang#124458 (Implement lldb formattter for "clang encoded" enums (LLDB 18.1+))
 - rust-lang#124459 (Stabilize exclusive_range_pattern)
 - rust-lang#124711 (Migrate `run-make/doctests-runtool` to rmake)
 - rust-lang#124725 (Meta: Enable the brand new triagebot transfer command)
 - rust-lang#124727 (Miri subtree update)

r? `@ghost`
`@rustbot` modify labels: rollup

…r=workingjubilee

Document That `f16` And `f128` Hardware Support is Limited (v2)

This PR is identical to rust-lang#123892, which was approved and merged but then removed from master by a force-push due to a [CI bug](https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/ci.20broken.3F).

r? ghost

Original PR description:

---

This adds a small paragraph to the recently added f16 and f128 types explaining that hardware support may be limited, and that performance may suffer as a result of that.

I mainly wrote this because I felt it may be useful to express in some form; as a launchpoint for readers of the documentation if they have issues with performance.

I tried to word the documentation in a way that doesn't create false assumptions (that f16/f128 is too slow to use, for instance), removing the software implementation part could mislead people to thinking that f16/f128 is only available on some platforms, not all, so I believe it is important to keep in.\
"not all *major* platforms" is specifically said so as to not be redundant, because not all platforms implement many things, but the average rustacean is probably going to be using x86_64 or aarch64 derived ISA's, which is who this documentation is targeted towards.

I'm not sure of the best way to word the documentation, or if it should even be added, but I feel like it may be useful to have (potentially in a reworded way, I'm not very confident in the current wording and cannot decide if that is because it is too vague to be useful or too specific to be generally correct).

Rollup merge of rust-lang#124750 - ultrabear:ultrabear_softfloatdoc, r=workingjubilee

Document That `f16` And `f128` Hardware Support is Limited (v2)

This PR is identical to rust-lang#123892, which was approved and merged but then removed from master by a force-push due to a [CI bug](https://rust-lang.zulipchat.com/#narrow/stream/242791-t-infra/topic/ci.20broken.3F).

r? ghost

Original PR description:

---

This adds a small paragraph to the recently added f16 and f128 types explaining that hardware support may be limited, and that performance may suffer as a result of that.

I mainly wrote this because I felt it may be useful to express in some form; as a launchpoint for readers of the documentation if they have issues with performance.

I tried to word the documentation in a way that doesn't create false assumptions (that f16/f128 is too slow to use, for instance), removing the software implementation part could mislead people to thinking that f16/f128 is only available on some platforms, not all, so I believe it is important to keep in.\
"not all *major* platforms" is specifically said so as to not be redundant, because not all platforms implement many things, but the average rustacean is probably going to be using x86_64 or aarch64 derived ISA's, which is who this documentation is targeted towards.

I'm not sure of the best way to word the documentation, or if it should even be added, but I feel like it may be useful to have (potentially in a reworded way, I'm not very confident in the current wording and cannot decide if that is because it is too vague to be useful or too specific to be generally correct).