…nt to their parents instead.

This commit is a reorganization of the `proc_macro` crate's public user-facing
API. This is the result of a number of discussions at the recent Rust All-Hands
where we're hoping to get the `proc_macro` crate into ship shape for
stabilization of a subset of its functionality in the Rust 2018 release.

The reorganization here is motivated by experiences from the `proc-macro2`,
`quote`, and `syn` crates on crates.io (and other crates which depend on them).
The main focus is future flexibility along with making a few more operations
consistent and/or fixing bugs. A summary of the changes made from today's
`proc_macro` API is:

* The `TokenNode` enum has been removed and the public fields of `TokenTree`
  have also been removed. Instead the `TokenTree` type is now a public enum
  (what `TokenNode` was) and each variant is an opaque struct which internally
  contains `Span` information. This makes the various tokens a bit more
  consistent, require fewer wrappers, and otherwise provides good
  future-compatibility as opaque structs are easy to modify later on.

* `Literal` integer constructors have been expanded to be unambiguous as to what
  they're doing and also allow for more future flexibility. Previously
  constructors like `Literal::float` and `Literal::integer` were used to create
  unsuffixed literals and the concrete methods like `Literal::i32` would create
  a suffixed token. This wasn't immediately clear to all users (the
  suffixed/unsuffixed aspect) and having *one* constructor for unsuffixed
  literals required us to pick a largest type which may not always be true. To
  fix these issues all constructors are now of the form
  `Literal::i32_unsuffixed` or `Literal::i32_suffixed` (for all integral types).
  This should allow future compatibility as well as being immediately clear
  what's suffixed and what isn't.

* Each variant of `TokenTree` internally contains a `Span` which can also be
  configured via `set_span`. For example `Literal` and `Term` now both
  internally contain a `Span` rather than having it stored in an auxiliary
  location.

* Constructors of all tokens are called `new` now (aka `Term::intern` is gone)
  and most do not take spans. Manufactured tokens typically don't have a fresh
  span to go with them and the span is purely used for error-reporting
  **except** the span for `Term`, which currently affects hygiene. The default
  spans for all these constructed tokens is `Span::call_site()` for now.

  The `Term` type's constructor explicitly requires passing in a `Span` to
  provide future-proofing against possible hygiene changes. It's intended that a
  first pass of stabilization will likely only stabilize `Span::call_site()`
  which is an explicit opt-in for "I would like no hygiene here please". The
  intention here is to make this explicit in procedural macros to be
  forwards-compatible with a hygiene-specifying solution.

* Some of the conversions for `TokenStream` have been simplified a little.

* The `TokenTreeIter` iterator was renamed to `token_stream::IntoIter`.

Overall the hope is that this is the "final pass" at the API of `TokenStream`
and most of `TokenTree` before stabilization. Explicitly left out here is any
changes to `Span`'s API which will likely need to be re-evaluated before
stabilization.

All changes in this PR have already been reflected to the [`proc-macro2`],
`quote`, and `syn` crates. New versions of all these crates have also been
published to crates.io.

Once this lands in nightly I plan on making an internals post again summarizing
the changes made here and also calling on all macro authors to give the APIs a
spin and see how they work. Hopefully pending no major issues we can then have
an FCP to stabilize later this cycle!

[`proc-macro2`]: https://docs.rs/proc-macro2/0.3.1/proc_macro2/

* Expand `!` tokens for inner doc comments
* Trim leading doc comment decoration in the string literal

Both of these should help bring the expansion inline with what `macro_rules!`
already does.

Closes rust-lang#49655
Closes rust-lang#49656

Make queries thread safe

This makes queries thread safe by removing the query stack and making queries point to their parents. Queries write to the query map when starting and cycles are detected by checking if there's already an entry in the query map. This makes cycle detection O(1) instead of O(n), where `n` is the size of the query stack.

This is mostly corresponds to the method I described [here](https://internals.rust-lang.org/t/parallelizing-rustc-using-rayon/6606).

cc @rust-lang/compiler

r? @michaelwoerister

…chenkov

Expand macros in `extern {}` blocks

This permits macro and proc-macro and attribute invocations (the latter only with the `proc_macro` feature of course) in `extern {}` blocks, gated behind a new `macros_in_extern` feature.

A tracking issue is now open at rust-lang#49476

closes rust-lang#48747

Bots that read the log can simply look for `[CI_JOB_NAME=...]` to find out
the job's name.

Chalkify - Tweak `Clause` definition and HRTBs

r? @nikomatsakis

…chenkov

proc_macro: Reorganize public API

This commit is a reorganization of the `proc_macro` crate's public user-facing
API. This is the result of a number of discussions at the recent Rust All-Hands
where we're hoping to get the `proc_macro` crate into ship shape for
stabilization of a subset of its functionality in the Rust 2018 release.

The reorganization here is motivated by experiences from the `proc-macro2`,
`quote`, and `syn` crates on crates.io (and other crates which depend on them).
The main focus is future flexibility along with making a few more operations
consistent and/or fixing bugs. A summary of the changes made from today's
`proc_macro` API is:

* The `TokenNode` enum has been removed and the public fields of `TokenTree`
  have also been removed. Instead the `TokenTree` type is now a public enum
  (what `TokenNode` was) and each variant is an opaque struct which internally
  contains `Span` information. This makes the various tokens a bit more
  consistent, require fewer wrappers, and otherwise provides good
  future-compatibility as opaque structs are easy to modify later on.

* `Literal` integer constructors have been expanded to be unambiguous as to what
  they're doing and also allow for more future flexibility. Previously
  constructors like `Literal::float` and `Literal::integer` were used to create
  unsuffixed literals and the concrete methods like `Literal::i32` would create
  a suffixed token. This wasn't immediately clear to all users (the
  suffixed/unsuffixed aspect) and having *one* constructor for unsuffixed
  literals required us to pick a largest type which may not always be true. To
  fix these issues all constructors are now of the form
  `Literal::i32_unsuffixed` or `Literal::i32_suffixed` (for all integral types).
  This should allow future compatibility as well as being immediately clear
  what's suffixed and what isn't.

* Each variant of `TokenTree` internally contains a `Span` which can also be
  configured via `set_span`. For example `Literal` and `Term` now both
  internally contain a `Span` rather than having it stored in an auxiliary
  location.

* Constructors of all tokens are called `new` now (aka `Term::intern` is gone)
  and most do not take spans. Manufactured tokens typically don't have a fresh
  span to go with them and the span is purely used for error-reporting
  **except** the span for `Term`, which currently affects hygiene. The default
  spans for all these constructed tokens is `Span::call_site()` for now.

  The `Term` type's constructor explicitly requires passing in a `Span` to
  provide future-proofing against possible hygiene changes. It's intended that a
  first pass of stabilization will likely only stabilize `Span::call_site()`
  which is an explicit opt-in for "I would like no hygiene here please". The
  intention here is to make this explicit in procedural macros to be
  forwards-compatible with a hygiene-specifying solution.

* Some of the conversions for `TokenStream` have been simplified a little.

* The `TokenTreeIter` iterator was renamed to `token_stream::IntoIter`.

Overall the hope is that this is the "final pass" at the API of `TokenStream`
and most of `TokenTree` before stabilization. Explicitly left out here is any
changes to `Span`'s API which will likely need to be re-evaluated before
stabilization.

All changes in this PR have already been reflected to the [`proc-macro2`],
`quote`, and `syn` crates. New versions of all these crates have also been
published to crates.io.

Once this lands in nightly I plan on making an internals post again summarizing
the changes made here and also calling on all macro authors to give the APIs a
spin and see how they work. Hopefully pending no major issues we can then have
an FCP to stabilize later this cycle!

[`proc-macro2`]: https://docs.rs/proc-macro2/0.3.1/proc_macro2/

Closes rust-lang#49596

typos

This commit updates our manifest generation for rustup to filter out any
components/extensions which are actually missing. This is intended to help
mitigate rust-lang#49462 by making the manifests reflect reality, that many targets now
are missing a `rust-docs` component rather than requiring it exists.

…utboats

…kennytm