Part of rust-lang#29378.

* rust-lang#42007 happens because the Session LintStore is emptied when linting.
* The Session LintStore is emptied because the checker (Early/LateContext)
  wants ownership.
* The checker wants ownership because it wants to mutate the pass objects
  and lint levels.

The ownership of the whole store is not essential, only the lint levels and
pass objects need to be owned. Therefore, these parts are extracted out of
the LintStore into a separate structure `LintSession`. The "check crates"
methods can operate on `&mut LintSession` instead of `&mut LintStore`.

This is a minor BREAKING CHANGE for lint writers since the `LintContext`
trait is changed: the `mut_lints` and `level_stack` methods are removed.
But no one outside of `librustc/lint/context.rs` is using these functions,
so it should be safe.

This is useful if parsing from stdin or a String and don't want to try and read in a module from another file. Instead we just leave a stub in the AST.

…tion

Not being an enum improves ergonomics, especially since NonEmpty could be Empty.  It can still be iterable without an extra "done" bit by making the range have !(start <= end), which is even possible without changing the Step trait.

Implements RFC 1980

Fixes rust-lang#42135

Found while fixing run-pass/range_inclusive test failure.

Fixes rust-lang#42139

This was breaking the libstd build for Redox.

These files are licensed under a different license
than the rest of the codebase. This causes potential
issues and inconveniences.
Relicense these files under the standard license.
I hold original copyright on that code.

Fixes rust-lang#36556

Generally useful, but also a prerequisite for moving a bunch of unit tests off Range::step_by.

Also, add detection to treat such comments as tidy errors.
We also remove the found_lib_feature code because it
was just repeating the found_feature code. Originally it
was intended to allow for gate-test lines for
lib features, but apparently nobody missed it.

Fixes: rust-lang#42099

This brings verbosity even to invocation of cargo itself

See rust-lang#33525 for details.

[Doc] Add `'static` and `Send` constraints explanations to `thread::spawn`

Part of rust-lang#29378.

Explains why the constraints on the closure and its return value are `'static` and `Send`.

Allows to tick of `thread::spawn` from the list of things to document in the `thread` module.

r? @steveklabnik

…t-id, r=nikomatsakis

Refactor: Move the mutable parts out of LintStore. Fix rust-lang#42007.

* rust-lang#42007 happens because the `Session` `LintStore` is emptied when linting.
* The `Session` `LintStore` is emptied because the checker (`Early`/`LateContext`) wants ownership.
* The checker wants ownership because it wants to mutate the pass objects and lint levels.

The ownership of the whole store is not essential, only the lint levels and pass objects need to be owned. Therefore, these parts are extracted out of the `LintStore` into a separate structure `LintSession`. The "check crates" methods can operate on `&mut LintSession` instead of `&mut LintStore`.

This is a minor *breaking change* for lint writers since the `LintContext` trait is changed: the `mut_lints` and `level_stack` methods are removed. But no one outside of `librustc/lint/context.rs` is using these functions, so it should be safe.

Add an option to the parser to avoid parsing out of line modules

This is useful if parsing from stdin or a String and don't want to try and read in a module from another file. Instead we just leave a stub in the AST.

…akis

Make assignments to `Copy` union fields safe

This is an accompanying PR to PR rust-lang#42068 stabilizing FFI unions.

This was first proposed in rust-lang#32836 (comment), see subsequent comments as well.
Assignments to `Copy` union fields do not read any data from the union and are [equivalent](rust-lang#32836 (comment)) to whole union assignments, which are safe, so they should be safe as well. This removes a significant number of "false positive" unsafe blocks, in code dealing with FFI unions in particular.

It desirable to make this change now, together with stabilization of FFI unions, because now it affecfts only unstable code, but later it will cause warnings/errors caused by `unused_unsafe` lint in stable code.

cc rust-lang#32836
r? @nikomatsakis

remove "much" from unicode diagnostic

The English seems slightly awkward to me, and it's unnecessary.

…turon

Make RangeInclusive just a two-field struct

Not being an enum improves ergonomics and consistency, especially since NonEmpty variant wasn't prevented from being empty.  It can still be iterable without an extra "done" bit by making the range have !(start <= end), which is even possible without changing the Step trait.

Implements merged rust-lang/rfcs#1980; tracking issue rust-lang#28237.

This is definitely a breaking change to anything consuming `RangeInclusive` directly (not as an Iterator) or constructing it without using the sugar.  Is there some change that would make sense before this so compilation failures could be compatibly fixed ahead of time?

r? @aturon (as FCP proposer on the RFC)

Fix building std without backtrace feature, which was broken in ca8b754

Fixes rust-lang#42139

Implement requires_synchronized_create() for Redox

This was breaking the libstd build for Redox.

libstd/sync/mpsc: relicense under rust license

These files are licensed under a different license
than the rest of the codebase. This causes potential
issues and inconveniences.
Relicense these files under the standard license.
I hold original copyright on that code.

Fixes rust-lang#36556

…ages, r=Mark-Simulacrum

Change error count messages

See rust-lang#33525 for details. r? @Mark-Simulacrum

Document drop more.

Adds two examples to Drop and describes the recursive drop on types that contain fields.

…excrichton

Override size_hint and propagate ExactSizeIterator for iter::StepBy

Generally useful, but also a prerequisite for moving a bunch of unit tests off `Range*::step_by`.

A small non-breaking subset of rust-lang#42110 (which I closed).

Includes two small documentation changes @ivandardi requested on that PR.

r? @alexcrichton

…x-1, r=nikomatsakis

incr.comp.: Track expanded spans instead of FileMaps.

This PR removes explicit tracking of FileMaps in response to rust-lang#42101. The reasoning behind being able to just *not* track access to FileMaps is similar to why we don't track access to the `DefId->DefPath` map:
1. One can only get ahold of a `Span` value by accessing the HIR (for local things) or a `metadata::schema::Entry` (for things from external crates).
2. For both of these things we compute a hash that incorporates the *expanded spans*, that is, what we hash is in the (FileMap independent) format `filename:line:col`.
3. Consequently, everything that emits a span should already be tracked via its dependency to something that has the span included in its hash and changes would be detected via that hash.

One caveat here is that we have to be conservative when exporting things in metadata. A crate can be built without debuginfo and would thus by default not incorporate most spans into the metadata hashes. However, a downstream crate can make an inline copy of things in the upstream crate and span changes in the upstream crate would then go undetected, even if the downstream uses them (e.g. by emitting debuginfo for an inlined function). For this reason, we always incorporate spans into metadata hashes for now (there might be more efficient ways to handle this safely when red-green tracking is implemented).

r? @nikomatsakis

Remove some needless // gate-test- comments

Also, add detection to treat such comments as tidy errors.
We also remove the found_lib_feature code because it
was just repeating the found_feature code. Originally it
was intended to allow for gate-test lines for
lib features, but apparently nobody missed it.

…=alexcrichton

bootstrap: Make bootstrap verbose if requested

Fixes: rust-lang#42099

…labnik

fix broken link to nomicon in Unsize docs

Add a missing link that is currently broken in the docs (see the last sentence of https://doc.rust-lang.org/std/marker/trait.Unsize.html)

…isdreavus

Add missing urls for OsStr docs

r? @rust-lang/docs