`Duration::from_secs_{f32, f64}` now use the results from the
non-panicking functions and unwrap it.

This also adds the error type used, `FromSecsError` and its `impl`s.

Add disambiugator to ExpnData

I still need to write a bunch of comments. Opening to see how bad the perf impact is.

cc https://github.com/rust-lang/rust/issues/79560

Rollup of 15 pull requests

Successful merges:

 - #79841 (More clear documentation for NonNull<T>)
 - #81072 (PlaceRef::ty: use method call syntax)
 - #81130 (Edit rustc_middle::dep_graph module documentation)
 - #81170 (Avoid hash_slice in VecDeque's Hash implementation)
 - #81243 (mir: Improve size_of handling when arg is unsized)
 - #81245 (Update cargo)
 - #81249 (Lower closure prototype after its body.)
 - #81252 (Add more self-profile info to rustc_resolve)
 - #81275 (Fix <unknown> queries and add more timing info to render_html)
 - #81281 (Inline methods of Path and OsString)
 - #81283 (Note library tracking issue template in tracking issue template.)
 - #81285 (Remove special casing of rustdoc in rustc_lint)
 - #81288 (rustdoc: Fix visibility of trait and impl items)
 - #81298 (replace RefCell with Cell in FnCtxt)
 - #81301 (Fix small typo)

Failed merges:

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

Due to macro expansion, its possible to end up with two distinct
`ExpnId`s that have the same `ExpnData` contents. This violates the
contract of `HashStable`, since two unequal `ExpnId`s will end up with
equal `Fingerprint`s.

This commit adds a `disambiguator` field to `ExpnData`, which is used to
force two otherwise-equivalent `ExpnData`s to be distinct.

Fix small typo

Fractional part of `12.34e56` seems to be incorrectly stated as '45' and not '34'

replace RefCell with Cell in FnCtxt

small cleanup

rustdoc: Fix visibility of trait and impl items

Fixes #81274.

r? `@jyn514`

Note library tracking issue template in tracking issue template.

Inline methods of Path and OsString

These methods are not generic, and therefore aren't candidates for cross-crate inlining without an `#[inline]` attribute.

Fix <unknown> queries and add more timing info to render_html

Closes https://github.com/rust-lang/rust/issues/81251.

##  Fix `<unknown>` queries

This happened because `alloc_query_strings` was never called.

##  Add more timing info to render_html

This still has some issues I'm not sure how to work out:

- `create_renderer` and `renderer_after_krate` aren't shown by default.
  I want something like `verbose_generic_activity_with_arg`, but it doesn't exist.

I'm also not sure how to show activities that aren't on by default - I
tried `-Z self-profile -Z self-profile-args=all`, but it didn't show up.

r? `@wesleywiser`

Add more self-profile info to rustc_resolve

The idea is to help me find out where the time is being spent in compiling the docs for `windows-rs`: https://github.com/microsoft/windows-rs/issues/420#issuecomment-764991646

Lower closure prototype after its body.

Fixes #79537.

r? `@Mark-Simulacrum`

Update cargo

5 commits in a73e5b7d567c3036b296fc6b33ed52c5edcd882e..783bc43c660bf39c1e562c8c429b32078ad3099b
2021-01-12 23:45:39 +0000 to 2021-01-20 19:02:26 +0000
- Fix some issues with `cargo doc` and the new feature resolver. (rust-lang/cargo#9077)
- Implement support for rust-version field in project metadata (rust-lang/cargo#8037)
- Fix a bug in Cargo's cyclic dep graph detection (rust-lang/cargo#9075)
- Typo correction: artifcats -> artifacts (rust-lang/cargo#9081)
- Remove stray backtick from doc (rust-lang/cargo#9079)

mir: Improve size_of handling when arg is unsized

As discussed on Zulip with `@RalfJung.`

Avoid hash_slice in VecDeque's Hash implementation

Fixes #80303.

Edit rustc_middle::dep_graph module documentation

This is similar to work approved and then closed in https://github.com/rust-lang/rust/pull/80325 due to a bad rebase.

PlaceRef::ty: use method call syntax

More clear documentation for NonNull<T>

Rephrase and hopefully clarify the discussion of covariance in `NonNull<T>` documentation.

I'm very much not an expert so someone should definitely double check the correctness of what I'm saying. At the same time, the new language makes more sense to me, so hopefully it also is more logical to others whose knowledge of covariance basically begins and ends with the [Rustonomicon chapter](https://doc.rust-lang.org/nomicon/subtyping.html).

Related to #48929.

This avoids each tool having to separately find and call
`self_profile_alloc_strings`.

- Don't compute the global context if it hasn't yet been computed

  This avoids giving extraneous errors about unresolved names if an error
  occurs during parsing.

- Show `create_renderer` and `renderer_after_crate` by default
- Don't rewrite `extra_verbose_generic_activity`

avoid promoting division, modulo and indexing operations that could fail

For division, `x / y` will still be promoted if `y` is a non-zero integer literal; however, `1/(1+1)` will not be promoted any more.

While at it, also see if we can reject promoting floating-point arithmetic (which are [complicated](https://github.com/rust-lang/unsafe-code-guidelines/issues/237) so maybe we should not promote them).

This will need a crater run to see if there's code out there that relies on these things being promoted.

If we can land this, promoteds in `fn`/`const fn` cannot fail to evaluate any more, which should let us do some simplifications in codegen/Miri!

Cc https://github.com/rust-lang/rfcs/pull/3027
Fixes https://github.com/rust-lang/rust/issues/61821
r? `@oli-obk`

Change branching in `iter.skip()`

Optimize branching in `Skip`, which was brought up in #80416.
This assumes that if `next` is called, it's likely that there will be more calls to `next`, and the branch for skip will only be hit once thus it's unlikely to take that path. Even w/o the `unlikely` intrinsic, it compiles more efficiently, I believe because the path where `next` is called is always taken.

It should be noted there are very few places in the compiler where `Skip` is used, so probably won't have a noticeable perf impact.

[New impl](https://godbolt.org/z/85rdj4)
[Old impl](https://godbolt.org/z/Wc74rh)

[Some additional asm examples](https://godbolt.org/z/feKzoz) although they really don't have a ton of difference between them.

Improve diagnostics when parsing angle args

https://github.com/rust-lang/rust/pull/79266 introduced parsing of generic arguments in associated type constraints, this however resulted in possibly very confusing error messages in cases in which closing angle brackets were missing such as in `Vec<(u32, _, _) = vec![]`, which outputs an incorrectly parsed equality constraint error, as noted by `@cynecx.`

This PR tries to provide better error messages in such cases.

r? `@petrochenkov`

Split up core/test/iter.rs into multiple files

This PR removes the `// ignore-tidy-filelength` at the top of [iter.rs](https://github.com/rust-lang/rust/blob/04f44fb9232dc960d213d0df4a203c387215a5ff/library/core/tests/iter.rs) by splitting it into several sub files. I have split the file per test, based on what I felt the test was really trying to test.
Addresses issue #60302.
- [associated_util.rs](https://github.com/rust-lang/rust/blob/d29180a8ed2752c5dfa2bca1d28ca05dc9bf6bf1/library/core/tests/iter/associated_util.rs) - For testing the module level functions. (Maybe should be renamed?)
- [collection.rs](https://github.com/rust-lang/rust/blob/d29180a8ed2752c5dfa2bca1d28ca05dc9bf6bf1/library/core/tests/iter/collection.rs) - For testing methods that use the values of all the items in an iterator, and creates one value from them, whether it be a Vec of all the values, or a number that represents the sum.
- [mod.rs](https://github.com/rust-lang/rust/blob/d29180a8ed2752c5dfa2bca1d28ca05dc9bf6bf1/library/core/tests/iter/mod.rs) - For utility structs used in all tests, and other tests I didn't know where to place.
- [range.rs](https://github.com/rust-lang/rust/blob/d29180a8ed2752c5dfa2bca1d28ca05dc9bf6bf1/library/core/tests/iter/range.rs) - For testing ranges.
- [transformation.rs](https://github.com/rust-lang/rust/blob/d29180a8ed2752c5dfa2bca1d28ca05dc9bf6bf1/library/core/tests/iter/transformation.rs) - For testing methods that transform all the values in an iterator.
- [util.rs](https://github.com/rust-lang/rust/blob/d29180a8ed2752c5dfa2bca1d28ca05dc9bf6bf1/library/core/tests/iter/util.rs) - For testing methods that provide utility in more specific use cases.

"Programatically"
-----------------------
You may have noticed I "Programatically" split up the file. [This is how](https://gist.github.com/danii/a58b3bcafa9faf1c3e4b01ad7495baf4) I managed to do that. 😛 Hope that's fine.

Refactor token collection to capture trailing token immediately

Split out from https://github.com/rust-lang/rust/pull/80689 - when we start capturing more information about attribute targets, we'll need to know in advance if we're capturing a trailing token or not.

r? `@ghost`

This happened because `alloc_query_strings` was never called.

Co-authored-by: NJoshua Nelson <joshua@yottadb.com>
Co-authored-by: NCamelid <camelidcamel@gmail.com>

Add doc aliases for memory allocations

This patch adds doc aliases for various C allocation functions, making it possible to search for the C-equivalent of a function and finding the (safe) Rust counterpart:

- `Vec::with_capacity` / `Box::new` / `vec!` -> alloc + malloc, allocates memory
- `Box::new_zeroed` -> calloc, allocates zeroed-out memory
- `Vec::{reserve,reserve_exact,try_reserve_exact,shrink_to_fit,shrink_to}` -> realloc, reallocates a previously allocated slice of memory

It's worth noting that `Vec::new` does not allocate, so we don't link to it. Instead people are probably looking for `Vec::with_capacity` or `vec!`. I hope this will allow people comfortable with the system allocation APIs to make it easier to find what they may be looking for.

Thanks!

This is no longer necessary now that rustdoc doesn't run
everybody_loops.

Rephrase and hopefully clarify the discussion of covariance in `NonNull<T>` documentation.

Add setgroups to std::os::unix::process::CommandExt

Should fix #38527. I'm not sure groups is the greatest name though.