rustc_metadata: Switch crate data iteration from a callback to iterator

The iteration looks more conventional this way, and some allocations are avoided.

intra-doc: Use an enum to represent URL fragments

This is a step in the direction of computing the links more lazily,
which I think will simplify the implementation of intra-doc links.
This will also make it easier to eventually use the actual `Res` for
associated items, enum variants, and fields, rather than their HTML
page's `Res`.

r? `@jyn514`

This is a step in the direction of computing the links more lazily,
which I think will simplify the implementation of intra-doc links.
This will also make it easier to eventually use the actual `Res` for
associated items, enum variants, and fields, rather than their HTML
page's `Res`.

Use hash_stable for hashing str

This seemed like an oversight. With this change the hash can go through the `HashStable` machinery directly.

Rollup of 7 pull requests

Successful merges:

 - #90586 (Relax priv-in-pub lint on generic bounds and where clauses of trait impls.)
 - #92112 (Fix the error of checking `base_expr` twice in type_changing_struct_update)
 - #92147 (rustc_builtin_macros: make asm mod public for rustfmt)
 - #92161 (resolve: Minor miscellaneous cleanups from #89059)
 - #92264 (Remove `maybe_uninit_extra` feature from Vec docs)
 - #92303 (Add test cases for issue #26186)
 - #92307 (Fix minor typos)

Failed merges:

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

Fix minor typos

Add test cases for issue #26186

Closes #26186

It seems that issue #26186 has been solved at some point since the issue has been last updated. I've merged together the examples that were supplied by `@Osspial,` `@Mark-Simulacrum,` `@Diggsey,` `@eefriedman` and `@shepmaster,` so that we can add this to the testing suite and prevent these issues from re-occurring.

Remove `maybe_uninit_extra` feature from Vec docs

In `Vec`, two doc tests are using `MaybeUninit::write` , stabilized in 1.55. This makes docs' usage of `maybe_uninit_extra` feature unnecessary.

resolve: Minor miscellaneous cleanups from #89059

`@bors` rollup=always

rustc_builtin_macros: make asm mod public for rustfmt

Follow up to #92016, as I'd completely missed that the mod we needed was internal

Fix the error of checking `base_expr` twice in type_changing_struct_update

Fixes #92010

Relax priv-in-pub lint on generic bounds and where clauses of trait impls.

The priv-in-pub lint is a legacy mechanism of the compiler, supplanted by a reachability-based [type privacy](https://github.com/rust-lang/rfcs/blob/master/text/2145-type-privacy.md) analysis. This PR does **not** relax type privacy; it only relaxes the lint (as proposed by the type privacy RFC) in the case of trait impls.

## Current Behavior
On public trait impls, it's currently an **error** to have a `where` bound constraining a private type with a trait:
```rust
pub trait Trait {}
pub struct Type {}

struct Priv {}
impl Trait for Priv {}

impl Trait for Type
where
    Priv: Trait // ERROR
{}
```

...and it's a **warning** to have have a public type constrained by a private trait:
```rust
pub trait Trait {}
pub struct Type {}

pub struct Pub {}
trait Priv {}
impl Priv for Pub {}

impl Trait for Type
where
    Pub: Priv // WARNING
{}
```

This lint applies to `where` clauses in other contexts, too; e.g. on free functions:
```rust
struct Priv<T>(T);
pub trait Pub {}
impl<T: Pub> Pub for Priv<T> {}

pub fn function<T>()
where
    Priv<T>: Pub // WARNING
{}
```

**These constraints could be relaxed without issue.**

## New Behavior
This lint is relaxed for `where` clauses on trait impls, such that it's okay to have a `where` bound constraining a private type with a trait:
```rust
pub trait Trait {}
pub struct Type {}

struct Priv {}
impl Trait for Priv {}

impl Trait for Type
where
    Priv: Trait // OK
{}
```

...and it's okay to have a public type constrained by a private trait:
```rust
pub trait Trait {}
pub struct Type {}

pub struct Pub {}
trait Priv {}
impl Priv for Pub {}

impl Trait for Type
where
    Pub: Priv // OK
{}
```

## Rationale
While the priv-in-pub lint is not essential for soundness, it *can* help programmers avoid pitfalls that would make their libraries difficult to use by others. For instance, such a lint *is* useful for free functions; e.g. if a downstream crate tries to call the `function` in the previous snippet in a generic context:
```rust
fn callsite<T>()
where
    Priv<T>: Pub // ERROR: omitting this bound is a compile error, but including it is too
{
    function::<T>()
}
```
...it cannot do so without repeating `function`'s `where` bound, which we cannot do because `Priv` is out-of-scope. A lint for this case is arguably helpful.

However, this same reasoning **doesn't** hold for trait impls. To call an unconstrained method on a public trait impl with private bounds, you don't need to forward those private bounds, you can forward the public trait:
```rust
mod upstream {
    pub trait Trait {
        fn method(&self) {}
    }
    pub struct Type<T>(T);

    pub struct Pub<T>(T);
    trait Priv {}
    impl<T: Priv> Priv for Pub<T> {}

    impl<T> Trait for Type<T>
    where
        Pub<T>: Priv // WARNING
    {}
}

mod downstream {
    use super::upstream::*;

    fn function<T>(value: Type<T>)
    where
        Type<T>: Trait // <- no private deets!
    {
        value.method();
    }
}
```

**This PR only eliminates the lint on trait impls.** It leaves it intact for all other contexts, including trait definitions, inherent impls, and function definitions. It doesn't need to exist in those cases either, but I figured I'd first target a case where it's mostly pointless.

## Other Notes
- See discussion [on zulip](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/relax.20priv-in-pub.20lint.20for.20trait.20impl.20.60where.60.20bounds/near/222458397).
- This PR effectively reverts #79291.

normalize env constness for nested obligations

Closes #92230.

rustdoc: remove unused Hash impl

Rustdoc: use `is_doc_hidden` method on more places

While profiling `rustdoc`, I noticed that finding out if some item is marked with `#[doc(hidden)]` is relatively hot, so I tried to optimize it.

I noticed that there is already a method called `is_doc_hidden` on `TyCtxt`, but it wasn't used much, so I replaced the manual calls to `attrs(...).has_word(...)` with this method. Just by doing that, perf. was improved locally, although I'm not sure if the semantics of the previous calls and this method are the same?

As another step, I tried to querify `is_doc_hidden`, but I didn't include that here until we see the perf. results from the first commit and until I find whether this change is OK at all :)

Can I ask for a perf. run? Thanks.

r? `@jyn514`

⬆ rust-analyzer

r? `@ghost`

Do not display `~const Drop` in rustdoc

Although `T: ~const Drop` is still at an experimental stage, we have already begun inserting these bounds in libstd. This change hides them from rustdoc because 1. `~const` should not be documented in general as it is not yet official syntax; 2. users are not expected to know what `~const Drop` means yet.

In `Vec`, two doc tests are using `MaybeUninit::write` , stabilized in 1.55. This makes docs' usage of `maybe_uninit_extra` feature unnecessary.

Add `#[inline]` modifier to `TypeId::of`

It was already inlined but it happened only in 4th InlinerPass on my testcase.
With `#[inline]` modifier it happens on 2nd pass.

Closes #74362

rustc_metadata: Merge `get_ctor_def_id` and `get_ctor_kind`

Also avoid decoding the whole `ty::AssocItem` to get a `has_self` flag.

A small optimization and cleanup extracted from https://github.com/rust-lang/rust/pull/89059.

update Miri

Fixes https://github.com/rust-lang/rust/issues/92246
r? `@ghost`

Constify `core::intrinsics::black_box` and `core::hint::black_box`.

`core::intrinsics::black_box` is already constified, but it wasn't marked as const (see: https://github.com/rust-lang/rust/blob/master/compiler/rustc_const_eval/src/interpret/intrinsics.rs#L471).

Tracking issue: None

CTFE eval_fn_call: use FnAbi to determine argument skipping and compatibility

This makes use of the `FnAbi` type in CTFE/Miri, which `@EddyB` has been saying for years is what we should do.^^ `FnAbi` is used to
- determine which arguments to skip (rather than the previous heuristic of skipping ZST arguments with the Rust ABI)
- impose further restrictions on whether caller and callee are consistent in how a given argument is passed

I was hoping it would also simplify the code, but that is not the case -- the previous type compatibility checks are still required (AFAIK), only the ZST skipping is gone and that took barely any code. We also need some hacks because `FnAbi` assumes a certain way of implementing `caller_location` (by passing extra arguments), but Miri can just read the caller location from the call stack so it doesn't need those arguments. (The fact that every backend has to separately implement support for these arguments seems suboptimal -- looks like this might have been better implemented on the MIR level.) To avoid having to implement those unnecessary arguments in Miri, we just compute *whether* the argument is present on the caller/callee side, but don't actually pass that argument around.

I have no idea if this looks the way `@EddyB` thinks it should look... but it makes Miri's test suite pass. ;)
One of rustc's tests fails unfortunately (`ui/const-generics/issues/issue-67739.rs`), some const generic code that is evaluated too early -- I think that should raise `TooGeneric` but instead it ICEs. My assumption is this is some FnAbi code that has not been properly tested on polymorphic code, but it might also be me calling that FnAbi code the wrong way.

r? `@oli-obk` `@EddyB`
Fixes https://github.com/rust-lang/rust/issues/56166
Miri PR at https://github.com/rust-lang/miri/pull/1928

RawVec: don't recompute capacity after allocating.

Currently it sets the capacity to `ptr.len() / mem::size_of::<T>()`
after any buffer allocation/reallocation. This would be useful if
allocators ever returned a `NonNull<[u8]>` with a size larger than
requested. But this never happens, so it's not useful.

Removing this slightly reduces the size of generated LLVM IR, and
slightly speeds up the hot path of `RawVec` growth.

r? `@ghost`

Remove useless `#[global_allocator]` from rustc and rustdoc.

This was added in #83152, which has several errors in its comments.

This commit also fix up the comments, which are quite wrong and
misleading.

r? `@alexcrichton`

Rollup of 5 pull requests

Successful merges:

 - #90625 (Add `UnwindSafe` to `Once`)
 - #92121 (disable test with self-referential generator on Miri)
 - #92166 (Fixed a small typo in ui test comments)
 - #92203 (Store a `DefId` instead of an `AdtDef` in `AggregateKind::Adt`)
 - #92231 (Update books)

Failed merges:

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

Update books

## nomicon

1 commits in 49681ea4a9fa81173dbe9ffed74b4d4a35eae9e3..c05c452b36358821bf4122f9c418674edd1d713d
2021-11-24 16:27:28 +0900 to 2021-12-13 15:23:48 +0900
- Update the guidance on uninitialized data with ptr::addr_of_mut (rust-lang/nomicon#325)

## reference

3 commits in 954f3d441ad880737a13e241108f791a4d2a38cd..06f9e61931bcf58b91dfe6c924057e42ce273ee1
2021-11-29 11:11:30 -0800 to 2021-12-17 07:31:40 -0800
- keep consistent for primitive types (rust-lang/reference#1118)
- README.md: link to mdbook docs (rust-lang/reference#1117)
- Say that `...` range patterns are rejected in the 2021 edition (rust-lang/reference#1114)

## book

4 commits in 5f9358faeb1f46e19b8a23a21e79fd7fe150491e..8a0bb3c96e71927b80fa2286d7a5a5f2547c6aa4
2021-12-05 21:33:16 -0500 to 2021-12-22 20:54:27 -0500
- Propagate edits back
- Fix number disagreement. Fixes rust-lang/book#2858.
- Wrap some code in main to make scopes clearer. Fixes rust-lang/book#2830.
- Respond to ch5 nostarch edits

## rustc-dev-guide

9 commits in a374e7d8bb6b79de45b92295d06b4ac0ef35bc09..9bf0028b557798ddd07a6f652e4d0c635d3d6620
2021-12-03 09:26:47 -0800 to 2021-12-20 21:53:57 +0900
- remove rustfix item in test intro (rust-lang/rustc-dev-guide#1277)
- Move date-check comment to fix Markdown syntax
- Update humor docs for special-casing ferris emoji
- Fix some broken links (rust-lang/rustc-dev-guide#1274)
- Update rustdoc internals
- Update HIR chapter to use `HirId` instead of `NodeId`
- Fix some broken links
- Update src/getting-started.md
- Improve documentation on r?

Store a `DefId` instead of an `AdtDef` in `AggregateKind::Adt`

The `AggregateKind` enum ends up in the final mir `Body`. Currently,
any changes to `AdtDef` (regardless of how significant they are)
will legitimately cause the overall result of `optimized_mir` to change,
invalidating any codegen re-use involving that mir.

This will get worse once we start hashing the `Span` inside `FieldDef`
(which is itself contained in `AdtDef`).

To try to reduce these kinds of invalidations, this commit changes
`AggregateKind::Adt` to store just the `DefId`, instead of the full
`AdtDef`. This allows the result of `optimized_mir` to be unchanged
if the `AdtDef` changes in a way that doesn't actually affect any
of the MIR we build.

Fixed a small typo in ui test comments