Update stdsimd module

[alexcrichton]

Pulls in a redesigned std::simd module as well as a replacement for the
is_target_feature_detected! macro

[rust-highfive]

r? @aturon

(rust_highfive has picked a reviewer for you, use r? to override)

[alexcrichton]

cc @gnzlbg

r? @kennytm

[kennytm]

You need to add #![feature(fn_must_use, doc_cfg)] to coresimd.

[00:24:45] warning: `#[must_use]` on methods is experimental (see issue #43302)
[00:24:45]    --> libcore/../stdsimd/coresimd/ppsv/api/minimal.rs:76:13
[00:24:45]     |
[00:24:45] 76  |               #[must_use = "replace_unchecked does not modify the original value - it returns a new vector with the value at `index` replaced by `new_value`d"]
[00:24:45]     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[00:24:45]     | 
[00:24:45]    ::: libcore/../stdsimd/coresimd/ppsv/v512.rs:124:1
[00:24:45]     |
[00:24:45] 124 | / simd_f_ty! {
[00:24:45] 125 | |     f64x8: 8, f64, b8x8, f64x8_tests |
[00:24:45] 126 | |     f64, f64, f64, f64, f64, f64, f64, f64 |
[00:24:45] 127 | |     x0, x1, x2, x3, x4, x5, x6, x7 |
[00:24:45] 128 | |     /// A 512-bit vector with 8 `f64` lanes.
[00:24:45] 129 | | }
[00:24:45]     | |_- in this macro invocation
[00:24:45]     |
[00:24:45]     = help: add #![feature(fn_must_use)] to the crate attributes to enable
[00:24:45] 
[00:24:45] error[E0658]: #[doc(cfg(...))] is experimental (see issue #43781)
[00:24:45]   --> libcore/../stdsimd/coresimd/mod.rs:52:5
[00:24:45]    |
[00:24:45] 52 |     #[doc(cfg(target_arch = "x86_64"))]
[00:24:45]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[00:24:45]    |
[00:24:45]    = help: add #![feature(doc_cfg)] to the crate attributes to enable
[00:24:45] 
[00:24:45]    Compiling alloc_jemalloc v0.0.0 (file:///checkout/src/liballoc_jemalloc)
[00:24:45] error: aborting due to previous error

[alexcrichton]

Ah indeed! Running a build locally as well...

[gnzlbg]

@alexcrichton is there a way to add a build bot to stdsimd that does a sanity check for these things?

If it takes too long to run we could just allow it to fail, and only try to make it pass before updating rust upstream.

[kennytm]

Travis passed, so

@bors r+

[bors]

📌 Commit 4163c4a has been approved by kennytm

[alexcrichton]

@bors: r=kennytm

cc @QuietMisdreavus had to back out rust-lang/stdarch#367 due to #48912 (comment)

[bors]

📌 Commit 512bafe has been approved by kennytm

[alexcrichton]

@gnzlbg

is there a way to add a build bot to stdsimd that does a sanity check for these things?

Perhaps yeah but everything's changing a rapid enough pace right now it's probably best to figure these things out at integration time rather than slowing down either portion

[bors]

⌛ Testing commit 512bafe0afddee957431c45eb83e4ee76734da79 with merge 351cb6006cfa7c6eefd8806b5c21a7503eb45594...

[bors]

💔 Test failed - status-travis

[alexcrichton]

@bors: r=kennytm

[bors]

📌 Commit f2a8556 has been approved by kennytm

[bors]

⌛ Testing commit f2a8556 with merge d12e1565ccec8e13f8e5e4cbbf84e825daea80ea...

[bors]

💔 Test failed - status-travis

[kennytm]

@bors retry

A spurious bug that should be fixed by #48938.