Match on it directly instead

Make the following methods of `std::net::IpAddr` unstable const under the `const_ip` feature:
- `is_unspecified`
- `is_loopback`
- `is_global`
- `is_multicast`

Also adds a test for these methods in a const context.

Possible because these methods delegate to the inner `Ipv4Addr` or `Ipv6Addr`, which were made const, and the recent stabilization of const control flow.

Part of #76205

The double underscores were used to work around issue #12808, which was
solved in 2016.

…GuillaumeGomez

Use adaptive SVG favicon for rustdoc like other rust sites

Use the theme-adaptive SVG favicon that was recently introduced [for the Rust site](rust-lang/www.rust-lang.org#1185) (and others).

(This PR is simply copied from the PR linked above, so see that for rationale.)

Closes #72165.

Before, Firefox on Linux:

![image](https://user-images.githubusercontent.com/13814214/89971811-34c0a900-dc2a-11ea-9aa6-a4aa9d66bed4.png)

After, Firefox on Linux (`prefers-color-scheme` set to `dark` by setting `ui.systemUsesDarkTheme` to a number value of `1` in `about:config`):

![image](https://user-images.githubusercontent.com/13814214/89971842-515ce100-dc2a-11ea-92e8-c374aaaf6031.png)

Make delegation methods of `std::net::IpAddr` unstably const

Make the following methods of `std::net::IpAddr` unstable const under the `const_ip` feature:
 - `is_unspecified`
 - `is_loopback`
 - `is_global`
 - `is_multicast`

Also adds a test for these methods in a const context.

Possible because these methods delegate to the inner `Ipv4Addr` or `Ipv6Addr`, which were made const ([PR#76205](#76142) and [PR#76206](#76206)), and the recent stabilization of const control flow.

Part of #76205

r? @ecstatic-morse

Allow a unique name to be assigned to dataflow graphviz output

Previously, if the same analysis were invoked multiple times in a single compilation session, the graphviz output for later runs would overwrite that of previous runs. Allow callers to add a unique identifier to each run so this can be avoided.

Documented From impls in std/sync/mpsc/mod.rs

This is for #51430.

r? @steveklabnik

Liballoc bench vec use mem take not replace

Typo fix: "satsify" -> "satisfy"

add array::from_ref

mirrors the methods in `std::slice` with the same name.

I guess this method previously didn't exist as there was close to no reason to create an array of size `1`.
This will change due to const generics in the near future.

Don't use an if guard to check equality with a constant

Match on it directly instead

Use `Self` in docs when possible

Fixes #76542.

I used `rg '\s*//[!/]\s+fn [\w_]+\(&?self, ' .` in `library/` to find instances, I found some with that and some by manually checking.

@rustbot modify labels: C-enhancement T-doc

Merge two almost identical match arms

Updated html_root_url for compiler crates

Closes #77103

r? @jyn514

Suggest `const_mut_refs`, not `const_fn` for mutable references in `const fn`

Resolves #77134.

Prior to #76850, most uses of `&mut` in `const fn` ~~required~~ involved two feature gates, `const_mut_refs` and `const_fn`. The first allowed all mutable borrows of locals. The second allowed only locals, arguments and return values whose types contained `&mut`. I switched the second check to the `const_mut_refs` gate. However, I forgot update the error message with the new suggestion.

Alternatively, we could revert to having two different feature gates for this. OP's code never borrows anything mutably, so it didn't need `const_mut_refs` in the past, only `const_fn`. I'd prefer to keep everything under a single gate, however.

r? @oli-obk

…, r=oli-obk

Suggest `const_fn_transmute`, not `const_fn`

More fallout from #76850 in the vein of #77134. The fix is the same. I looked through the structured errors file and didn't see any more of this kind of diagnostics bug.

r? @oli-obk

…scores, r=Mark-Simulacrum

Remove workaround for deref issue that no longer exists.

The double underscores were used to work around issue #12808, which was solved in 2016.

… r=oli-obk

Followup to #76673

Resolves #76673 (comment)
r? @tmiasko