- add initial version to support sockets
- use TcpStream as test case
- HermitCore uses smoltcp as IP stack for pure Rust applications
- further functionalities (e.g. UDP support) will be added step by step
tidy: Better license checks.
This implements some improvements to the license checks in tidy:
* Use `cargo_metadata` instead of parsing vendored crates. This allows license checks to run without vendoring enabled, and allows the checks to run on PR builds.
* Check for stale entries.
* Check that the licenses for exceptions are what we think they are.
* Verify exceptions do not leak into the runtime.
Closes#62618Closes#62619Closes#63238 (I think)
There are some substantive changes here. The follow licenses have changed from the original comments:
* openssl BSD+advertising clause to Apache-2.0
* pest MPL2 to MIT/Apache-2.0
* smallvec MPL2 to MIT/Apache-2.0
* clippy lints MPL2 to MIT OR Apache-2.0
Remove some imports to the rustc crate
- When we have `NestedVisitorMap::None`, we use `type Map = dyn intravisit::Map<'v>;` instead of the actual map. This doesn't actually result in dynamic dispatch (in the future we may want to use an associated type default to simplify the code).
- Use `rustc_session::` imports instead of `rustc::{session, lint}`.
r? @Zoxc
Changes:
````
rustup https://github.com/rust-lang/rust/pull/69738
rustup https://github.com/rust-lang/rust/pull/68944
Make use of `or_patterns` feature
rustup https://github.com/rust-lang/rust/pull/69589/
Rustup to rust-lang/rust#69076
Don't convert Path to lossy str
Use `into_path`
Use pattern matching instead of manually checking condition
Fix typo
Remove git2 dependency.
Document that wildcard_imports doesn't warn about `use ...::prelude::*;`
Change changelog formatting
Update changelog_update doc to reflect the actual ordering of the changelog
Update CHANGELOG.md
````
Fixes#70007
Changes:
````
Rustup to rust-lang/rust#69674
Use visit_place
Check for mutation
Only fires on temporaries
Extend `redundant_clone` to the case that cloned value is not consumed
add CR feedback
Improve documentation
Use `edition:2018` flag more widely
Update tests/ui/needless_doc_main.rs
Move links to the end of each chapter on adding_lints
Move links to the end of each chapter on CONTRIBUTING
Clean-up adding_lints.md
Clean-up CONTRIBUTING.md
needless_doc_main: only check rust code
Use `node_type_opt` over `node_type`
Fix doc
Fix ICE with trivial_bounds feature
clippy_lints: readme: don't mention crates.io since it is no longer used to publish clippy.
update rust-lang.github.io to rustc-dev-guide.rust-lang.org
Improve placeholder in map_unit_fn
Fix match single binding when in a let stmt
Improve error messages for {option,result}_map_unit_fn
Mention the setup instructions in CONTRIBUTING
redundant_pattern: take binding (ref, ref mut) into account in suggestion.
check_pat: delay creation of the "normal" vec until we reach the branch where is is actually needed
deps: bump itertools 0.8 -> 0.9
add lint on File::read_to_string and File::read_to_end
transition rustc-guide to rustc-dev-guide
Rename macro_use_import -> macro_use_imports
warn on macro_use attr
Fix deploy script for tag deploys
````
Fixes#69957
Polonius: update `polonius-engine` to 0.12.0
Since @albins won't have the time to finish up #68993 for a while, I'll take care of the trivial remaining tasks (rebasing, taking care of tidy/rustfmt).
I'll r? @nikomatsakis since they're assigned to #68993, but have actually [already reviewed it pre-rebase](https://github.com/rust-lang/rust/pull/68993#issuecomment-586413089).
When CI passes: I'll notify bors and close#68993, since this PR supersedes it.
Remove experimental chalk option
As suggested by @nikomatsakis [here](https://github.com/rust-lang/rust/pull/68807#issuecomment-583339932).
The current version of chalk used by the experimental `-Zchalk` flag is [v0.9.0, which is over a year old](https://crates.io/crates/chalk-engine). Since v0.9.0, chalk has seen [a lot of further development](https://github.com/rust-lang/chalk/compare/41dfe13...master), and the intent is to eventually upgrade rustc to use a more recent chalk.
However, it will take a decent chunk of effort to upgrade the current experimental chalk support, and it is currently [blocking at least some PRs](https://github.com/rust-lang/rust/pull/68807) due to chalk:0.9.0's use of unstable features. So for the interim until the next chalk release and experimental rustc integration, we remove the chalk-specific code from rustc.
[experiment] Support linking from a .rlink file
Flag `-Z no-link` was previously introduced, which allows creating an `.rlink` file to perform compilation without linking. This change enables linking from an `.rlink` file.
Part of Issue #64191
Flag `-Z no-link` was previously introduced, which allows creating
an `.rlink` file to perform compilation without linking.
This change enables linking from an `.rlink` file.
Changes:
````
Update jobserver.
Update tar.
Emit report on error with Ztimings.
Do not run `formats_source` if `rustfmt` is not available
Fix rebuild_sub_package_then_while_package on HFS.
Remove likely brittle test.
Install rustfmt for testing in CI
Fix build-std collisions.
Fix BuildScriptOutput when a build script is run multiple times.
Fix required-features using renamed dependencies.
Fix using global options before an alias.
Update changelog for 1.42.
Bump to 0.44.0.
Log rustfmt output if it fails; also do not check that rustfmt exists
Update pretty_env_logger requirement from 0.3 to 0.4
Swap std::sync::mpsc channel with crossbeam_channel
Fix tests on Linux/MacOS
Fix typo.
Add tests
Deduplicate warnings about missing rustfmt
Log entry 2: first implementation
Refactor code
Stabilize config-profile.
Log entry 1
Format code
Remove tempdir after install
Keep existing package with git install
Use non-ephemeral workspace
Test that git install reads virtual manifest
Fix failing test
Search for root manifest with ephemeral workspaces
Support out-dir in build section of Cargo configuration file
````
Update cargo, books
## cargo
9 commits in ad3dbe10e1e654fb1f032a5dd9481d7cbaa00d65..f6449ba236db31995255ac5e4cad4ab88296a7c6
2020-01-13 21:37:15 +0000 to 2020-01-21 16:15:39 +0000
- Fix wrong directories in host_libdir. (rust-lang/cargo#7798)
- Update humantime requirement from 1.2.0 to 2.0.0 (rust-lang/cargo#7815)
- Fix doc_target test which no longer works on stable/beta. (rust-lang/cargo#7817)
- Fix some erroneous em-dashes in man pages. (rust-lang/cargo#7814)
- fix some clippy warnings (rust-lang/cargo#7808)
- Don't assume iowait always increases on Linux (rust-lang/cargo#7803)
- Add and update some doc comments. (rust-lang/cargo#7800)
- Consistently use em-dash in environment documentation page. (rust-lang/cargo#7799)
- Load credentials only when needed (rust-lang/cargo#7774)
## reference
3 commits in e1157538e86d83df0cf95d5e33bd943f80d0248f..11e893fc1357bc688418ddf1087c2b7aa25d154d
2019-12-22 13:13:14 +0100 to 2020-01-18 21:24:08 +0100
- Small improvements to types/pointer.md (rust-lang-nursery/reference#726)
- repr(transparent): mention align=1 requirement (rust-lang-nursery/reference#737)
- Elaborate on how to use an extern static correctly (rust-lang-nursery/reference#736)
## book
4 commits in 5c5cfd2e94cd42632798d9bd3d1116133e128ac9..87dd6843678575f8dda962f239d14ef4be14b352
2019-12-16 09:27:21 -0600 to 2020-01-20 15:20:40 -0500
- Fix listing numbers (rust-lang/book#2227)
- Move `async` and `await` keywords to 'Currently in Use' (rust-lang/book#2140)
- More cleanup - remove unneeded files (rust-lang/book#2213)
- Small cleanups extracted from the bigger pr i'm working on (rust-lang/book#2212)
## rust-by-example
1 commits in 1d59403cb5269c190cc52a95584ecc280345495a..1c2bd024d13f8011307e13386cf1fea2180352b5
2019-12-27 08:27:05 -0300 to 2020-01-20 12:18:36 -0300
- CamelCase -> UpperCamelCase (rust-lang/rust-by-example#1302)
## embedded-book
1 commits in 9493b7d4dc97eda439bd8780f05ad7b234cd1cd7..4d78994915af1bde9a95c04a8c27d8dca066232a
2019-12-27 20:05:00 +0000 to 2020-01-14 08:25:25 +0000
- Update .gitattributes (rust-embedded/book#221)
Optimize size/speed of Unicode datasets
The overall implementation has the same general idea as the prior approach,
which was based on a compressed trie structure, but modified to use less space
(and, coincidentally, be an overall performance improvement).
Sizes | Old | New | New/current
-- | -- | -- | --
Alphabetic | 4616 | 2982 | 64.60%
Case_Ignorable | 3144 | 2112 | 67.18%
Cased | 2376 | 934 | 39.31%
Cc | 19 | 43 | 226.32%
Grapheme_Extend | 3072 | 1734 | 56.45%
Lowercase | 2328 | 985 | 42.31%
N | 2648 | 1239 | 46.79%
Uppercase | 1978 | 934 | 47.22%
White_Space | 241 | 140 | 58.09%
| | |
Total | 20422 | 11103 | 54.37%
This table shows the size of the old and new tables in bytes. The most important
of these tables is "Grapheme_Extend", as it is present in essentially all Rust
programs due to being called from `str`'s Debug impl (`char::escape_debug`). In
a representative case given by this [blog post] for the embedded world, the
shrinking in this PR shrinks the final binary by 1,604 bytes, from 14,440 to
12,836.
The performance of these new tables, based on the (rough) benchmark of linearly
scanning the entire valid set of chars, querying for each `is_*`, is roughly
~50% better, though in some cases is either on par or slightly (3-5%) worse. In
practice, I believe the size benefits of this PR are the main concern. The new
implementation has been tested to be equivalent to the current nightly in terms
of returned values on the set of valid chars.
A (relatively) high-level explanation of the specific compression scheme used
can be found [in the generator].
This is split into three commits -- the first adds the generator which produces
the Rust code for the tables, the second adds support code for the lookup, and
the third actually swaps the current implementation out for the new one.
[blog post]: https://jamesmunns.com/blog/fmt-unreasonably-expensive/
[in the generator]: https://github.com/Mark-Simulacrum/rust/blob/unicode-tables/src/tools/unicode-table-generator/src/raw_emitter.rs
Rollup of 12 pull requests
Successful merges:
- #67784 (Reset Formatter flags on exit from pad_integral)
- #67914 (Don't run const propagation on items with inconsistent bounds)
- #68141 (use winapi for non-stdlib Windows bindings)
- #68211 (Add failing example for E0170 explanation)
- #68219 (Untangle ZST validation from integer validation and generalize it to all zsts)
- #68222 (Update the wasi-libc bundled with libstd)
- #68226 (Avoid calling tcx.hir().get() on CRATE_HIR_ID)
- #68227 (Update to a version of cmake with windows arm64 support)
- #68229 (Update iovec to a version with no winapi dependency)
- #68230 (Update libssh2-sys to a version that can build for aarch64-pc-windows…)
- #68231 (Better support for cross compilation on Windows.)
- #68233 (Update compiler_builtins with changes to fix 128 bit integer remainder for aarch64 windows.)
Failed merges:
r? @ghost
Update compiler_builtins with changes to fix 128 bit integer remainder for aarch64 windows.
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Update libssh2-sys to a version that can build for aarch64-pc-windows…
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Update iovec to a version with no winapi dependency
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Update to a version of cmake with windows arm64 support
I have been investigating enabling panic=unwind for aarch64-pc-windows-msvc (see #65313) and building rustc and cargo hosted on aarch64-pc-windows-msvc.
Split MIR building into its own crate
This moves `rustc_mir::{build, hair, lints}` to `rustc_mir_build`.
The new crate only has a `provide` function as it's public API.
Based on #67898
cc @Centril @rust-lang/compiler
r? @oli-obk
Extract `rustc_ast_passes`, move gating, & refactor linting
Based on https://github.com/rust-lang/rust/pull/67770.
This PR extracts a crate `rustc_ast_passes`:
- `ast_validation.rs`, which is contributed by `rustc_passes` (now only has HIR based passes) -- the goal here is to improve recompilation of the parser,
- `feature_gate.rs`, which is contributed by `syntax` and performs post-expansion-gating & final erroring for pre-expansion gating,
- `show_span`, which is contributed by `syntax`.
To facilitate this, we first have to also:
- Move `{leveled_}feature_err{_err}` from `syntax::feature_gate::check` into `rustc_session::parse`.
- Move `get_features` into `rustc_parse::config`, the only place it is used.
- Move some some lint datatypes and traits, e.g. `LintBuffer`, `BufferedEarlyLint`, `BuiltinLintDiagnostics`, `LintPass`, and `LintArray` into `rustc_session::lint`.
- Move all the hard-wired lint `static`s into `rustc_session::lint::builtin`.
build-std compatible sanitizer support
### Motivation
When using `-Z sanitizer=*` feature it is essential that both user code and
standard library is instrumented. Otherwise the utility of sanitizer will be
limited, or its use will be impractical like in the case of memory sanitizer.
The recently introduced cargo feature build-std makes it possible to rebuild
standard library with arbitrary rustc flags. Unfortunately, those changes alone
do not make it easy to rebuild standard library with sanitizers, since runtimes
are dependencies of std that have to be build in specific environment,
generally not available outside rustbuild process. Additionally rebuilding them
requires presence of llvm-config and compiler-rt sources.
The goal of changes proposed here is to make it possible to avoid rebuilding
sanitizer runtimes when rebuilding the std, thus making it possible to
instrument standard library for use with sanitizer with simple, although
verbose command:
```
env CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS=-Zsanitizer=thread cargo test -Zbuild-std --target x86_64-unknown-linux-gnu
```
### Implementation
* Sanitizer runtimes are no long packed into crates. Instead, libraries build
from compiler-rt are used as is, after renaming them into `librusc_rt.*`.
* rustc obtains runtimes from target libdir for default sysroot, so that
they are not required in custom build sysroots created with build-std.
* The runtimes are only linked-in into executables to address issue #64629.
(in previous design it was hard to avoid linking runtimes into static
libraries produced by rustc as demonstrated by sanitizer-staticlib-link
test, which still passes despite changes made in #64780).
cc @kennytm, @japaric, @firstyear, @choller
Standard library support for riscv64gc-unknown-linux-gnu
Add std support for RISC-V 64-bit GNU/Linux and update libc for RISC-V support.
r? @alexcrichton
This replaces cargo-fmt with rustfmt with --skip-children which should
allow us to format code without running into rust-lang/rustfmt#3930.
This also bumps up the version of rustfmt used to a more recent one.
Update cargo, books
Update nomicon, cargo, reference, book, rust-by-example, embedded-book
## nomicon
2 commits in 041c46e692a2592853aeca132c8dfe8eb5a79a9e..8be35b201f9cf0a4c3fcc96c83ac21671dcf3112
2019-11-20 16:46:45 +0100 to 2019-12-01 13:02:12 -0500
- Update unwinding.md
- ci: remove needless rust-docs component
## cargo
15 commits in 626f0f40efd32e6b3dbade50cd53fdfaa08446ba..5a139f7e6d67fd8a416a3f19d8e01581d24c0333
2019-12-03 16:53:04 +0000 to 2019-12-10 20:17:50 +0000
- Bump cargo-platform version. (rust-lang/cargo#7693)
- Add a test for `cargo locate-project` (rust-lang/cargo#7690)
- Emit error on [target.'cfg(debug_assertions)'.dependencies] and similar (rust-lang/cargo#7660)
- Update the layout of `Cargo Commands` in doc (rust-lang/cargo#7687)
- Features and dependencies can't have the same name (rust-lang/cargo#7682)
- Fix some typos in doc (rust-lang/cargo#7672)
- Add test for `NAME` environment variable when `cargo new` (rust-lang/cargo#7667)
- Add test for `GIT_COMMITTER_EMAIL` when `cargo new` (rust-lang/cargo#7666)
- document support for Bitbucket Pipelines badges (rust-lang/cargo#7663)
- Add cargo-vendor to the list of cargo commands in doc (rust-lang/cargo#7659)
- Fix typo in section 'Caching the Cargo home in CI' (rust-lang/cargo#7661)
- Docs: Add an appendix on git authentication. (rust-lang/cargo#7658)
- Remove --offline empty index error. (rust-lang/cargo#7655)
- Change the link destination of cargo book contribution (rust-lang/cargo#7657)
- Add a --offline hint. (rust-lang/cargo#7654)
## reference
2 commits in 9e843aeb4df083522c7277179bbaa25d0507731c..787e8d84034a4a0ae17084bbae25474152144b9a
2019-11-24 17:44:04 +0100 to 2019-12-10 10:01:29 -0800
- Update for visibility syntax changes. (rust-lang-nursery/reference#722)
- document `bind_by_move_pattern_guards` (rust-lang-nursery/reference#720)
## book
2 commits in 81ebaa2a3f88d4d106516c489682e64cacba4f60..ef8bb568035ded8ddfa30a9309026638cc3c8136
2019-11-15 08:30:04 -0800 to 2019-11-28 11:00:04 -0600
- Remove optional commas from match arms in ch18-03 (rust-lang/book#2176)
- Remove call_box() from ch20-03 (rust-lang/book#2177)
## rust-by-example
1 commits in 4835e025826729827a94fdeb7cb85fed288d08bb..b7ac1bc76b7d02a43c83b3a931d226f708aa1ff4
2019-11-14 09:20:43 -0300 to 2019-12-02 11:38:43 -0300
- Make TryFrom & TryInto example editable (rust-lang/rust-by-example#1297)
## embedded-book
1 commits in 5ca585c4a7552efb546e7681c3de0712f4ae4fdc..c26234930282210849256e4ecab925f0f2daf3be
2019-08-27 13:39:14 +0000 to 2019-12-07 17:25:11 +0000
- Fix `impl Gpio` -> `impl GpioConfig` (rust-embedded/book#216)
rustllvm relies on the `LLVMRustStringWriteImpl` symbol existing, but
this symbol was previously defined in a *downstream* crate
(rustc_codegen_llvm, which depends on rustc_llvm.
While this somehow worked under the old 'separate bootstrap step for
codegen' scheme, it meant that rustc_llvm could not actually be built by
itself, since it relied linking to the downstream rustc_codegen_llvm
crate.
Now that librustc_codegen_llvm is just a normal crate, we actually try
to build a standalone rustc_llvm when we run tests. This commit moves
`LLVMRustStringWriteImpl` into rustc_llvm (technically the rustllvm
directory, which has its contents built by rustc_llvm). This ensures
that we can build each crate in the graph by itself, without requiring
that any downstream crates be linked in as well.
This commit builds on #65501 continue to simplify the build system and
compiler now that we no longer have multiple LLVM backends to ship by
default. Here this switches the compiler back to what it once was long
long ago, which is linking LLVM directly to the compiler rather than
dynamically loading it at runtime. The `codegen-backends` directory of
the sysroot no longer exists and all relevant support in the build
system is removed. Note that `rustc` still supports a dynamically loaded
codegen backend as it did previously, it just no longer supports
dynamically loaded codegen backends in its own sysroot.
Additionally as part of this the `librustc_codegen_llvm` crate now once
again explicitly depends on all of its crates instead of implicitly
loading them through the sysroot. This involved filling out its
`Cargo.toml` and deleting all the now-unnecessary `extern crate`
annotations in the header of the crate. (this in turn required adding a
number of imports for names of macros too).
The end results of this change are:
* Rustbuild's build process for the compiler as all the "oh don't forget
the codegen backend" checks can be easily removed.
* Building `rustc_codegen_llvm` is much simpler since it's simply
another compiler crate.
* Managing the dependencies of `rustc_codegen_llvm` is much simpler since
it's "just another `Cargo.toml` to edit"
* The build process should be a smidge faster because there's more
parallelism in the main rustc build step rather than splitting
`librustc_codegen_llvm` out to its own step.
* The compiler is expected to be slightly faster by default because the
codegen backend does not need to be dynamically loaded.
* Disabling LLVM as part of rustbuild is still supported, supporting
multiple codegen backends is still supported, and dynamic loading of a
codegen backend is still supported.
In which we implement illegal subset relations errors using Polonius
This PR is the rustc side of implementing subset errors using Polonius. That is, in
```rust
fn foo<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
y
}
```
returning `y` requires that `'b: 'a` but we have no evidence of that, so this is an error. (Evidence that the relation holds could come from explicit bounds, or via implied bounds).
Polonius outputs one such error per CFG point where the free region's placeholder loan unexpectedly flowed into another free region. While all these CFG locations could be useful in diagnostics in the future, rustc does not do that (and the duplication is only partially handled in the rest of the errors/diagnostics infrastructure, e.g. duplicate suggestions will be shown by the "outlives suggestions" or some of the `#[rustc_*]` NLL/MIR debug dumps), so I deduplicated the errors.
(The ordering also matters, otherwise some of the elided lifetime naming would change behaviour).
I've blessed a couple of tests, where the output is currently suboptimal:
- the `hrtb-perfect-forwarding` tests mix subset errors with higher-ranked subtyping, however the plan is for chalk to eventually take care of some of this to generate polonius constraints (i.e. it's not polonius' job). Until that happens, polonius will not see the error that NLL sees.
- some other tests have errors and diagnostics specific to `'static`, I _believe_ this to be because of it being treated as more "special" than in polonius. I believe the output is not wrong, but could be better, and appears elsewhere (I feel we'll need to look at polonius' handling of `'static` at some point in the future, maybe to match a bit more what NLL does when it produces errors)
I'll create a tracking issue in the polonius repo to record these 2 points (and a general "we'll need to go over the blessed output" issue, much like we did for NLLs)
The last blessed test is because it's an improvement: in this case, more errors/suggestions were computed, instead of the existing code path where this case apparently stops at the first error.
The `Naive` variant in Polonius computes those errors, so this PR also switches the default variant to that, as we're also in the process of temporarily deactivating all other variants (which exist mostly for performance considerations) until we have completed more work on completeness and correctness, before focusing on efficiency once again.
While most of the correctness in this PR is hidden in the polonius compare-mode (which of course passes locally), I've added a couple of smoke-tests to the existing ones, so that we have some confidence that it works (and keeps working) until we're in a position where we can run them on CI.
As mentioned during yesterday's wg-polonius meeting, @nikomatsakis has already read through most of this PR (and which is matching what they thought needed to be done [during the recent Polonius sprint](https://hackmd.io/CGMNjt1hR_qYtsR9hgdGmw#Compiler-notes-on-generating-the-placeholder-loans-support)), but Matthew was hopefully going to review (again, not urgent), so:
r? @matthewjasper
(This updates to the latest `polonius-engine` release, and I'm not sure whether `Cargo.lock` updates can easily be rolled up, but apart from that: this changes little that's tested on CI, so seems safe-ish to rollup ?)
Update measureme crate to 0.5.0
This PR updates the `measureme` self-profiling crate to the latest release. Heads up, this version changes the trace file format, so the `summarize` tool on perf.rlo needs to be updated to 0.5 too.
r? @Mark-Simulacrum
cc @wesleywiser
- adapt to the new polonius `FactTypes` API
- reorganize the type aliases referring to polonius to avoid referencing the inner atom or fact types multiple times: only one input and output types should be enough for everyone. They could equally be in `borrow_check` as `nll` though.
Move Sessions into (new) librustc_session
This PR moves `ParseSess` and `Session` from their current locations into a new crate, `librustc_session`.
There are several intents behind this change. librustc is a very large crate, and we want to split it up over time -- this movement removes the sizeable session module from it. It also helps allow for future movement of things not coupled to TyCtxt but coupled to Session out of the crate.
This movement allows allows for a future follow-up PR which unifies Session and ParseSess, allowing for a single source of truth for APIs interested in global options throughout the compiler; the ParseSess is already created directly as a member of Session in the current compiler (i.e., we do not first construct a ParseSess and then move it into Session later in the compilation).
This PR intentionally avoids changing numerous imports throughout the tree to new locations of the moved types; this is needless noise and can be done as needed.
In the process of moving the sessions back, the lint system received an update as well -- notably, early buffered lints are no longer ad-hoc declared as enum pairs and later associated with proper lint declarations. They are still separately handled (buffered), it is a little unclear whether this is truly necessary, but regardless is left for future PRs.
Many of the types moved back are sort of ad-hoc placed into the same crate (librustc_session) instead of creating other crates; it's unclear whether this is actually a good thing, but it seemed better than creating numerous tiny crates which served no purpose on their own.
