This avoids conflicts when installing with rustup; rustup does not currently
support overlapping installations.

See the failed build in

rust-lang#75555 (comment)

for an example where we need this in real life

They were carried over from once_cell crate, but they are not entirely
correct (as miri now supports more things), and we don't run miri
tests for std, so let's just remove them.

Maybe one day we'll run miri in std, but then we can just re-install
these attributes.

move const param structural match checks to wfcheck

fixes rust-lang#75047 fixes rust-lang#74950

We currently check for structural match violations inside of `type_of`.
As we need to check the array length when checking if `[NonEq; arr_len]` is structural match, we potentially require the variance of an expression. Computing the variance requires `type_of` for all types though, resulting in a cycle error.

r? @varkor @eddyb

…tic-morse

mir building: fix some comments

r? @oli-obk

At least I hope these fixes are right, please double-check.^^

…not-overlap, r=pietroalbini

Adjust installation place for compiler docs

This avoids conflicts when installing with rustup; rustup does not currently
support overlapping installations.

r? @matthiaskrgr

Make OnceCell<T> transparent to dropck

See the failed build in

rust-lang#75555 (comment)

for an example where we need this in real life

r? @ghost

…aumegomez

Fix intra-doc links for inherent impls that are both lang items and not the default impl

I found in rust-lang#75464 (comment) that `str::to_uppercase()` doesn't resolve while `str::trim()` does. The only real difference is that `to_uppercase` is defined in `alloc`, while trim is defined in `core`. It turns out that rustdoc was ignoring `lang_items.str_alloc_impl()` - it saw them in `collect_trait_impls`, but not for intra-doc links.

This uses the same `impls` for all parts of rustdoc, so that there can be no more inconsistency. It does have the slight downside that the matches are no longer exhaustive but it will be very clear if a new lang item is missed because it will panic when you try to document it (and if you don't document it, does rustdoc really need to know about it?).

~~This needs a test case (probably just `str::to_uppercase`).~~ Added.

This is best reviewed commit-by-commit.

r? @GuillaumeGomez

…jyn514

Move to intra doc links for std::io

Helps with rust-lang#75080.

@rustbot modify labels: T-doc, A-intra-doc-links, T-rustdoc

r? @jyn514

I had no problems with those files so I added some small links here and there.

Remove `#[cfg(miri)]` from OnceCell tests

They were carried over from once_cell crate, but they are not entirely
correct (as miri now supports more things), and we don't run miri
tests for std, so let's just remove them.

Maybe one day we'll run miri in std, but then we can just re-install
these attributes.