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Uplift the let_underscore lints from clippy into rustc. #97739

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merged 25 commits into from
Sep 2, 2022

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a2aaron
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@a2aaron a2aaron commented Jun 4, 2022

This PR resolves #97241.

This PR adds three lints from clippy--let_underscore_drop, let_underscore_lock, and let_underscore_must_use, which are meant to capture likely-incorrect uses of let _ = ... bindings (in particular, doing this on a type with a non-trivial Drop causes the Drop to occur immediately, instead of at the end of the scope. For a type like MutexGuard, this effectively releases the lock immediately, which is almost certainly the wrong behavior)

In porting the lints from clippy I had to copy over a bunch of utility functions from clippy_util that these lints also relied upon. Is that the right approach?

Note that I've set the must_use and drop lints to Allow by default and set lock to Deny by default (this matches the same settings that clippy has). In talking with @estebank he informed me to do a Crater run (I am not sure what type of Crater run to request here--I think it's just "check only"?)

On the linked issue, there's some discussion about using must_use and Drop together as a heuristic for when to warn--I did not implement this yet.

r? @estebank

This lint checks for statements similar to `let _ = foo`, where `foo` is
a type that implements `Drop`. These types of let statements cause the
expression in them to be dropped immediately, instead of at the end of
the scope. Such behavior can be surprizing, especially if you are
relying on the value to be dropped at the end of the scope. Instead, the
binding should be an underscore prefixed name (like `_unused`) or the
value should explicitly be passed to `std::mem::drop()` if the value
really should be dropped immediately.
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @estebank (or someone else) soon.

Please see the contribution instructions for more information.

@rustbot rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jun 4, 2022
@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 4, 2022
Similar to `let_underscore_drop`, this lint checks for statements similar
to `let _ = foo`, where `foo` is a lock guard. These types of let
statements are especially problematic because the lock gets released
immediately, instead of at the end of the scope. This behavior is almost
always the wrong thing.
Similar to `let_underscore_drop`, this lint checks for statements similar
to `let _ = foo`, where `foo` is an expression marked `must_use`.
These lints are very noisy and are allow-by-default in clippy anyways.
Hence, setting them to allow-by-default here makes more sense than
warning constantly on these cases.
This commit uses `span_suggestion_verbose` to add what specific code
changes can be done as suggested by the lint--in this case, either binding
the expression to an unused variable or using `std::mem::drop` to drop
the value explicitly.
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Clippy sets this lint to Deny by default, and it having the lint be Deny
is useful for when we test the lint against a Crater run.
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Thanks @a2aaron. I left a few questions.

compiler/rustc_lint/src/let_underscore.rs Outdated Show resolved Hide resolved
compiler/rustc_lint/src/let_underscore.rs Outdated Show resolved Hide resolved
src/test/ui/let_underscore/let_underscore_drop.rs Outdated Show resolved Hide resolved
const SYNC_GUARD_PATHS: [&[&str]; 5] = [
&["std", "sync", "mutex", "MutexGuard"],
&["std", "sync", "rwlock", "RwLockReadGuard"],
&["std", "sync", "rwlock", "RwLockWriteGuard"],
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Can those paths be replaced by diagnostic items? This will make all this more robust to code being moved within std.

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These paths were taken directly from the clippy implementation (which is also why they're hardcoded right now--there is a clippy issue meant to address that for clippy though). I can add a diagnostic item for these types, but I'm wondering if something similar to clippy's has_significant_drop already exists? It would make the lint much easier to implement and would generalize to other types well.

For now, however, I've added some diagnostic items.

&["std", "sync", "rwlock", "RwLockReadGuard"],
&["std", "sync", "rwlock", "RwLockWriteGuard"],
&["parking_lot", "raw_mutex", "RawMutex"],
&["parking_lot", "raw_rwlock", "RawRwLock"],
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I don't know the policy here: is rustc supposed to warn on inappropriate use of non-std crates?

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I'll remove the parking_lot specific paths for now, unless someone wants to keep them in.

compiler/rustc_lint/src/let_underscore.rs Outdated Show resolved Hide resolved
compiler/rustc_lint/src/let_underscore.rs Outdated Show resolved Hide resolved
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If the type has a trivial Drop implementation, then it is probably irrelevant
that the type was dropped immediately, since nothing important
happens on drop. Hence, we can bail out early instead of doing some
expensive checks.
…lock`

Using diagnostic items avoids having to update the paths if the guard
types ever get moved around for some reason. Additionally, it also greatly
simplifies the `is_sync_lock` check.
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@joshtriplett joshtriplett added the T-lang Relevant to the language team, which will review and decide on the PR/issue. label Jun 5, 2022
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👍 for adding let_underscore_lock and making it deny by default; that seems likely to catch bugs.

Adding let_underscore_drop and making it allow by default seems fine as well; I don't think we ever want to make that warn or error, since it's legitimate code, but I can imagine someone wanting to find and catch such code.

However, I'm not sure I understand the value of let_underscore_must_use. let _ = ... seems like exactly the pattern people normally use to intentionally ignore a must_use; under what circumstances would someone want to get a warning or error about this?

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a2aaron commented Jun 5, 2022

However, I'm not sure I understand the value of let_underscore_must_use. let _ = ... seems like exactly the pattern people normally use to intentionally ignore a must_use; under what circumstances would someone want to get a warning or error about this?

I added it to match the corresponding clippy lint, but I think you're right--if people really want it, clippy would probably be a more appropriate tool for that, I'll remove let_underscore_must_use.

We don't actually care about running these programs, only checking the
warnings they generate.
The `let_underscore_must_use` lint was really only added because clippy
included it, but it doesn't actually seem very useful.
I forgot to add the diagnostic to the actual types in `std` earlier.
@bors bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 5, 2022
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estebank commented Sep 1, 2022

@bors r+

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bors commented Sep 1, 2022

📌 Commit 76c90c3 has been approved by estebank

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 1, 2022
bors added a commit to rust-lang-ci/rust that referenced this pull request Sep 2, 2022
…llaumeGomez

Rollup of 9 pull requests

Successful merges:

 - rust-lang#97739 (Uplift the `let_underscore` lints from clippy into rustc.)
 - rust-lang#99583 (Add additional methods to the Demand type)
 - rust-lang#100147 (optimization of access level table construction)
 - rust-lang#100552 (rustc_target: Add a compatibility layer to separate internal and user-facing linker flavors)
 - rust-lang#100827 (Simplify MIR opt tests)
 - rust-lang#101166 (Generate error index with mdbook instead of raw HTML pages)
 - rust-lang#101294 (Fix rust-lang#100844 rebase accident)
 - rust-lang#101298 (rustdoc: remove unused CSS `#main-content > .since`)
 - rust-lang#101304 (Add autolabels for `A-query-system`)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 07f43a1 into rust-lang:master Sep 2, 2022
@rustbot rustbot added this to the 1.65.0 milestone Sep 2, 2022
dtolnay added a commit to dtolnay/scratch that referenced this pull request Sep 3, 2022
For whatever reason, the #![cfg_attr(feature = "cargo-clippy", allow(let_underscore_drop))]
attributes already in the code stopped working in the most recent nightly (2022-09-03).
Likely in connection with rust-lang/rust#97739 ?

    error: non-binding `let` on a type that implements `Drop`
     --> build.rs:8:5
      |
    8 |     let _ = fs::remove_dir_all(&out_dir);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
      = note: `-D clippy::let-underscore-drop` implied by `-D clippy::pedantic`
      = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
     --> build.rs:9:5
      |
    9 |     let _ = fs::create_dir(&out_dir);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
      = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
       --> src/lib.rs:128:5
        |
    128 |     let _ = fs::create_dir(&p);
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
        |
        = note: `-D clippy::let-underscore-drop` implied by `-D clippy::pedantic`
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop
dtolnay added a commit to serde-rs/serde that referenced this pull request Sep 3, 2022
For whatever reason, the #![cfg_attr(feature = "cargo-clippy", allow(let_underscore_drop))]
attributes already in the code stopped working in the most recent nightly (2022-09-03).
Likely in connection with rust-lang/rust#97739 ?

    error: non-binding `let` on a type that implements `Drop`
       --> serde/src/de/mod.rs:958:13
        |
    958 |             let _ = visitor;
        |             ^^^^^^^^^^^^^^^^
        |
        = note: `-D clippy::let-underscore-drop` implied by `-D clippy::pedantic`
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
       --> serde/src/de/mod.rs:992:13
        |
    992 |             let _ = visitor;
        |             ^^^^^^^^^^^^^^^^
        |
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1616:9
         |
    1616 |         let _ = deserializer;
         |         ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1640:9
         |
    1640 |         let _ = deserializer;
         |         ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1651:9
         |
    1651 |         let _ = seq;
         |         ^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1662:9
         |
    1662 |         let _ = map;
         |         ^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1673:9
         |
    1673 |         let _ = data;
         |         ^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/private/de.rs:1440:13
         |
    1440 |             let _ = visitor;
         |             ^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/private/de.rs:2163:13
         |
    2163 |             let _ = visitor;
         |             ^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop
dtolnay added a commit to serde-rs/serde that referenced this pull request Sep 3, 2022
For whatever reason, the #![cfg_attr(feature = "cargo-clippy", allow(let_underscore_drop))]
attributes already in the code stopped working in the most recent nightly (2022-09-03).
Likely in connection with rust-lang/rust#97739 ?

    error: non-binding `let` on a type that implements `Drop`
       --> serde/src/de/mod.rs:958:13
        |
    958 |             let _ = visitor;
        |             ^^^^^^^^^^^^^^^^
        |
        = note: `-D clippy::let-underscore-drop` implied by `-D clippy::pedantic`
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
       --> serde/src/de/mod.rs:992:13
        |
    992 |             let _ = visitor;
        |             ^^^^^^^^^^^^^^^^
        |
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1616:9
         |
    1616 |         let _ = deserializer;
         |         ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1640:9
         |
    1640 |         let _ = deserializer;
         |         ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1651:9
         |
    1651 |         let _ = seq;
         |         ^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1662:9
         |
    1662 |         let _ = map;
         |         ^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1673:9
         |
    1673 |         let _ = data;
         |         ^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/private/de.rs:1440:13
         |
    1440 |             let _ = visitor;
         |             ^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/private/de.rs:2163:13
         |
    2163 |             let _ = visitor;
         |             ^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop
dtolnay added a commit to serde-rs/serde that referenced this pull request Sep 3, 2022
For whatever reason, the #![cfg_attr(feature = "cargo-clippy", allow(let_underscore_drop))]
attributes already in the code stopped working in the most recent nightly (2022-09-03).
Likely in connection with rust-lang/rust#97739 ?

    error: non-binding `let` on a type that implements `Drop`
       --> serde/src/de/mod.rs:958:13
        |
    958 |             let _ = visitor;
        |             ^^^^^^^^^^^^^^^^
        |
        = note: `-D clippy::let-underscore-drop` implied by `-D clippy::pedantic`
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
       --> serde/src/de/mod.rs:992:13
        |
    992 |             let _ = visitor;
        |             ^^^^^^^^^^^^^^^^
        |
        = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1616:9
         |
    1616 |         let _ = deserializer;
         |         ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1640:9
         |
    1640 |         let _ = deserializer;
         |         ^^^^^^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1651:9
         |
    1651 |         let _ = seq;
         |         ^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1662:9
         |
    1662 |         let _ = map;
         |         ^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/de/mod.rs:1673:9
         |
    1673 |         let _ = data;
         |         ^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/private/de.rs:1440:13
         |
    1440 |             let _ = visitor;
         |             ^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop

    error: non-binding `let` on a type that implements `Drop`
        --> serde/src/private/de.rs:2163:13
         |
    2163 |             let _ = visitor;
         |             ^^^^^^^^^^^^^^^^
         |
         = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`
         = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_underscore_drop
bors added a commit to rust-lang/rust-clippy that referenced this pull request Oct 23, 2022
Mark `let_underscore_lock` and `let_underscore_drop` as uplifted

Here I've renamed both the uplifted lints, however rustc's `let_underscore_lock` is slightly less capable than the clippy lint as it doesn't catch `parking_lot` types or `Result<Guard, ..>`, should we still remove it? The `Result` change looks like it was unintentional to me so that could probably be fixed upstream

changelog: Uplift [`let_underscore_drop`] to rustc rust-lang/rust#97739
changelog: Remove overlap between rustc's `let_underscore_lock` and Clippy's [`let_underscore_lock`]

r? `@flip1995`
@detly
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detly commented Nov 13, 2022

The 1.65.0 changelog says

Add lints let_underscore_drop, let_underscore_lock, and let_underscore_must_use from Clippy

But this comment and b5b5b54 seems to indicate that let_underscore_must_use was omitted. Is the changelog wrong?

wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this pull request Nov 27, 2022
Pkgsrc changes:
 * We now manage to build for mipsel-unknown-netbsd, but despite the
   target spec saying cpu = "mips3", the compiler manages to emit 64-bit
   instructions which cause "illegal instruction" error.  Will need more
   work.  The mipsel-unknown-netbsd entry is commentd out since there
   is no 1.64.0 bootstrap.
 * Managed to retain the build of aarch64_be, llvm needed a patch to
   avoid use of neon instructions in the BE case (llvm doesn't support
   use of neon in BE mode).  Ref. patch to
   src/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h.
 * The minimum gcc version is now 7.x, and that includes the cross-compiler
   for the targets.  For i386 this also needs to /usr/include/gcc-7 include
   files in the target root, because immintrin.h from gcc 5 is not
   compatible with gcc 7.x.  This applies for the targets where we build
   against a root from netbsd-8 (sparc64, powerpc, i386), and files/gcc-wrap
   gets a hack for this.
 * Pick up tweak for -latomic inclusion from
   rust-lang/rust#104220
   and
   rust-lang/rust#104572
 * Retain ability to do 32-bit NetBSD, by changing from 64 to 32 bit
   types in library/std/src/sys/unix/thread_parker/netbsd.rs.
 * I've struggled a bit to get the "openssl-src" build with -latomic
   where it's needed.  I introduce "NetBSD-generic32" system type and
   use it for the NetBSD mipsel target.  There is another attempt to
   do the same in the patch to vendor/openssl-sys/build/main.rs.
 * Bump bootstraps to 1.64.0, checksum updates.

Upstream changes:

Version 1.65.0 (2022-11-03)
==========================

Language
--------
- [Error on `as` casts of enums with `#[non_exhaustive]` variants]
  (rust-lang/rust#92744)
- [Stabilize `let else`](rust-lang/rust#93628)
- [Stabilize generic associated types (GATs)]
  (rust-lang/rust#96709)
- [Add lints `let_underscore_drop`, `let_underscore_lock`, and
  `let_underscore_must_use` from Clippy]
  (rust-lang/rust#97739)
- [Stabilize `break`ing from arbitrary labeled blocks ("label-break-value")]
  (rust-lang/rust#99332)
- [Uninitialized integers, floats, and raw pointers are now considered
  immediate UB](rust-lang/rust#98919).
  Usage of `MaybeUninit` is the correct way to work with uninitialized
  memory.
- [Stabilize raw-dylib for Windows x86_64, aarch64, and thumbv7a]
  (rust-lang/rust#99916)
- [Do not allow `Drop` impl on foreign ADTs]
  (rust-lang/rust#99576)

Compiler
--------
- [Stabilize -Csplit-debuginfo on Linux]
  (rust-lang/rust#98051)
- [Use niche-filling optimization even when multiple variants have
  data] (rust-lang/rust#94075)
- [Associated type projections are now verified to be well-formed
  prior to resolving the underlying type]
  (rust-lang/rust#99217)
- [Stringify non-shorthand visibility correctly]
  (rust-lang/rust#100350)
- [Normalize struct field types when unsizing]
  (rust-lang/rust#101831)
- [Update to LLVM 15](rust-lang/rust#99464)
- [Fix aarch64 call abi to correctly zeroext when needed]
  (rust-lang/rust#97800)
- [debuginfo: Generalize C++-like encoding for enums]
  (rust-lang/rust#98393)
- [Add `special_module_name` lint]
  (rust-lang/rust#94467)
- [Add support for generating unique profraw files by default when
  using `-C instrument-coverage`]
  (rust-lang/rust#100384)
- [Allow dynamic linking for iOS/tvOS targets]
  (rust-lang/rust#100636)

New targets:
- [Add armv4t-none-eabi as a tier 3 target]
  (rust-lang/rust#100244)
- [Add powerpc64-unknown-openbsd and riscv64-unknown-openbsd as tier 3 targets]
  (rust-lang/rust#101025)
- Refer to Rust's [platform support page][platform-support-doc] for more
  information on Rust's tiered platform support.

Libraries
---------
- [Don't generate `PartialEq::ne` in derive(PartialEq)]
  (rust-lang/rust#98655)
- [Windows RNG: Use `BCRYPT_RNG_ALG_HANDLE` by default]
  (rust-lang/rust#101325)
- [Forbid mixing `System` with direct system allocator calls]
  (rust-lang/rust#101394)
- [Document no support for writing to non-blocking stdio/stderr]
  (rust-lang/rust#101416)
- [`std::layout::Layout` size must not overflow `isize::MAX` when
  rounded up to `align`](rust-lang/rust#95295)
  This also changes the safety conditions on
  `Layout::from_size_align_unchecked`.

Stabilized APIs
---------------
- [`std::backtrace::Backtrace`]
  (https://doc.rust-lang.org/stable/std/backtrace/struct.Backtrace.html)
- [`Bound::as_ref`]
  (https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.as_ref)
- [`std::io::read_to_string`]
  (https://doc.rust-lang.org/stable/std/io/fn.read_to_string.html)
- [`<*const T>::cast_mut`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_mut)
- [`<*mut T>::cast_const`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_const)

These APIs are now stable in const contexts:
- [`<*const T>::offset_from`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from)
- [`<*mut T>::offset_from`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from)

Cargo
-----
- [Apply GitHub fast path even for partial hashes]
  (rust-lang/cargo#10807)
- [Do not add home bin path to PATH if it's already there]
  (rust-lang/cargo#11023)
- [Take priority into account within the pending queue]
  (rust-lang/cargo#11032).
  This slightly optimizes job scheduling by Cargo, with typically
  small improvements on larger crate graph builds.

Compatibility Notes
-------------------
- [`std::layout::Layout` size must not overflow `isize::MAX` when
  rounded up to `align`] (rust-lang/rust#95295).
  This also changes the safety conditions on
  `Layout::from_size_align_unchecked`.
- [`PollFn` now only implements `Unpin` if the closure is `Unpin`]
  (rust-lang/rust#102737).
  This is a possible breaking change if users were relying on the
  blanket unpin implementation.  See discussion on the PR for
  details of why this change was made.
- [Drop ExactSizeIterator impl from std::char::EscapeAscii]
  (rust-lang/rust#99880)
  This is a backwards-incompatible change to the standard library's
  surface area, but is unlikely to affect real world usage.
- [Do not consider a single repeated lifetime eligible for elision
  in the return type] (rust-lang/rust#103450)
  This behavior was unintentionally changed in 1.64.0, and this
  release reverts that change by making this an error again.
- [Reenable disabled early syntax gates as future-incompatibility
  lints] (rust-lang/rust#99935)
- [Update the minimum external LLVM to 13]
  (rust-lang/rust#100460)
- [Don't duplicate file descriptors into stdio fds]
  (rust-lang/rust#101426)
- [Sunset RLS](rust-lang/rust#100863)
- [Deny usage of `#![cfg_attr(..., crate_type = ...)]` to set the
  crate type] (rust-lang/rust#99784)
  This strengthens the forward compatibility lint
  deprecated_cfg_attr_crate_type_name to deny.
- [`llvm-has-rust-patches` allows setting the build system to treat
  the LLVM as having Rust-specific patches]
  (rust-lang/rust#101072)
  This option may need to be set for distributions that are building
  Rust with a patched LLVM via `llvm-config`, not the built-in
  LLVM.

Internal Changes
----------------

These changes do not affect any public interfaces of Rust, but they represent
significant improvements to the performance or internals of rustc and related
tools.

- [Add `x.sh` and `x.ps1` shell scripts]
  (rust-lang/rust#99992)
- [compiletest: use target cfg instead of hard-coded tables]
  (rust-lang/rust#100260)
- [Use object instead of LLVM for reading bitcode from rlibs]
  (rust-lang/rust#98100)
- [Enable MIR inlining for optimized compilations]
  (rust-lang/rust#91743)
  This provides a 3-10% improvement in compiletimes for real world
  crates. See [perf results]
  (https://perf.rust-lang.org/compare.html?start=aedf78e56b2279cc869962feac5153b6ba7001ed&end=0075bb4fad68e64b6d1be06bf2db366c30bc75e1&stat=instructions:u).
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Jan 23, 2023
Pkgsrc changes:
 * pkglint cleanups, bump bootstrap kits to 1.65.0.
 * New target: mipsel-unknown-netbsd, for cpu=mips32 with soft-float.
 * Managed to retain the build of aarch64_be, llvm needed a patch to
   avoid use of neon instructions in the BE case (llvm doesn't support
   use of neon in BE mode).  Ref. patch to
   src/llvm-project/llvm/lib/Support/BLAKE3/blake3_impl.h.
   Also submitted upstream of LLVM to the BLAKE3 maintainers.
 * The minimum gcc version is now 7.x, and that includes the
   cross-compiler for the targets.  For i386 this also needs to
   /usr/include/gcc-7 include files in the target root, because
   immintrin.h from gcc 5 is not compatible with gcc 7.x.  This
   applies for the targets where we build against a root from netbsd-8
   (sparc64, powerpc, i386), and files/gcc-wrap gets a hack for this.
 * Pick up tweak for -latomic inclusion from
   rust-lang/rust#104220
   and
   rust-lang/rust#104572
 * Retain ability to do 32-bit NetBSD, by changing from 64 to 32 bit
   types in library/std/src/sys/unix/thread_parker/netbsd.rs.
 * I've tried to get the "openssl-src" build with -latomic where it's
   needed.  I've introduced the "NetBSD-generic32" system type and use
   it for the NetBSD mipsel target.  There is another attempt to do
   the same in the patch to vendor/openssl-sys/build/main.rs.


Upstream changes:

Version 1.66.1 (2023-01-10)
===========================

- Added validation of SSH host keys for git URLs in Cargo
  ([CVE-2022-46176](https://www.cve.org/CVERecord?id=CVE-2022-46176))


Version 1.66.0 (2022-12-15)
===========================

Language
--------
- [Permit specifying explicit discriminants on all `repr(Int)`
  enums](rust-lang/rust#95710)
  ```rust
  #[repr(u8)]
  enum Foo {
      A(u8) = 0,
      B(i8) = 1,
      C(bool) = 42,
  }
  ```
- [Allow transmutes between the same type differing only in
  lifetimes](rust-lang/rust#101520)
- [Change constant evaluation errors from a deny-by-default lint to a
  hard error](rust-lang/rust#102091)
- [Trigger `must_use` on `impl Trait` for
  supertraits](rust-lang/rust#102287) This
  makes `impl ExactSizeIterator` respect the existing `#[must_use]`
  annotation on `Iterator`.
- [Allow `..X` and `..=X` in
  patterns](rust-lang/rust#102275)
- [Uplift `clippy::for_loops_over_fallibles` lint into
  rustc](rust-lang/rust#99696)
- [Stabilize `sym` operands in inline
  assembly](rust-lang/rust#103168)
- [Update to Unicode 15](rust-lang/rust#101912)
- [Opaque types no longer imply lifetime
  bounds](rust-lang/rust#95474) This is a
  soundness fix which may break code that was erroneously relying on this
  behavior.

Compiler
--------
- [Add armv5te-none-eabi and thumbv5te-none-eabi tier 3
  targets](rust-lang/rust#101329)
  - Refer to Rust's [platform support page][platform-support-doc] for
    more information on Rust's tiered platform support.
- [Add support for linking against macOS universal
  libraries](rust-lang/rust#98736)

Libraries
---------
- [Fix `#[derive(Default)]` on a generic `#[default]` enum adding
  unnecessary `Default`
  bounds](rust-lang/rust#101040)
- [Update to Unicode 15](rust-lang/rust#101821)

Stabilized APIs
---------------
- [`proc_macro::Span::source_text`](https://doc.rust-lang.org/stable/proc_macro/struct.Span.html#method.source_text)
- [`uX::{checked_add_signed, overflowing_add_signed,
  saturating_add_signed,
  wrapping_add_signed}`](https://doc.rust-lang.org/stable/std/primitive.u8.html#method.checked_add_signed)
- [`iX::{checked_add_unsigned, overflowing_add_unsigned,
  saturating_add_unsigned,
  wrapping_add_unsigned}`](https://doc.rust-lang.org/stable/std/primitive.i8.html#method.checked_add_unsigned)
- [`iX::{checked_sub_unsigned, overflowing_sub_unsigned,
  saturating_sub_unsigned,
  wrapping_sub_unsigned}`](https://doc.rust-lang.org/stable/std/primitive.i8.html#method.checked_sub_unsigned)
- [`BTreeSet::{first, last, pop_first,
  pop_last}`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeSet.html#method.first)
- [`BTreeMap::{first_key_value, last_key_value, first_entry, last_entry,
  pop_first,
  pop_last}`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html#method.first_key_value)
- [Add `AsFd` implementations for stdio lock types on
  WASI.](rust-lang/rust#101768)
- [`impl TryFrom<Vec<T>> for Box<[T;
  N]>`](https://doc.rust-lang.org/stable/std/boxed/struct.Box.html#impl-TryFrom%3CVec%3CT%2C%20Global%3E%3E-for-Box%3C%5BT%3B%20N%5D%2C%20Global%3E)
- [`core::hint::black_box`](https://doc.rust-lang.org/stable/std/hint/fn.black_box.html)
- [`Duration::try_from_secs_{f32,f64}`](https://doc.rust-lang.org/stable/std/time/struct.Duration.html#method.try_from_secs_f32)
- [`Option::unzip`](https://doc.rust-lang.org/stable/std/option/enum.Option.html#method.unzip)
- [`std::os::fd`](https://doc.rust-lang.org/stable/std/os/fd/index.html)

Rustdoc
-------
- [Add Rustdoc warning for invalid HTML tags in the
  documentation](rust-lang/rust#101720)

Cargo
-----
- [Added `cargo remove` to remove dependencies from
  Cargo.toml](https://doc.rust-lang.org/nightly/cargo/commands/cargo-remove.html)
- [`cargo publish` now waits for the new version to be downloadable
  before exiting](rust-lang/cargo#11062)

See [detailed release notes](https://github.com/rust-lang/cargo/blob/master/CHANGELOG.md#cargo-166-2022-12-15) for more.

Compatibility Notes
-------------------
- [Only apply `ProceduralMasquerade` hack to older versions of
  `rental`](rust-lang/rust#94063)
- [Don't export `__heap_base` and `__data_end` on
  wasm32-wasi.](rust-lang/rust#102385)
- [Don't export `__wasm_init_memory` on
  WebAssembly.](rust-lang/rust#102426)
- [Only export `__tls_*` on
  wasm32-unknown-unknown.](rust-lang/rust#102440)
- [Don't link to `libresolv` in libstd on
  Darwin](rust-lang/rust#102766)
- [Update libstd's libc to 0.2.135 (to make `libstd` no longer pull in
  `libiconv.dylib` on
  Darwin)](rust-lang/rust#103277)
- [Opaque types no longer imply lifetime
  bounds](rust-lang/rust#95474)
  This is a soundness fix which may break code that was erroneously
  relying on this behavior.
- [Make `order_dependent_trait_objects` show up in future-breakage
  reports](rust-lang/rust#102635)
- [Change std::process::Command spawning to default to inheriting the
  parent's signal mask](rust-lang/rust#101077)

Internal Changes
----------------

These changes do not affect any public interfaces of Rust, but they
represent significant improvements to the performance or internals of
rustc and related tools.

- [Enable BOLT for LLVM
  compilation](rust-lang/rust#94381)
- [Enable LTO for
  rustc_driver.so](rust-lang/rust#101403)


Version 1.65.0 (2022-11-03)
==========================

Language
--------
- [Error on `as` casts of enums with `#[non_exhaustive]` variants]
  (rust-lang/rust#92744)
- [Stabilize `let else`](rust-lang/rust#93628)
- [Stabilize generic associated types (GATs)]
  (rust-lang/rust#96709)
- [Add lints `let_underscore_drop`, `let_underscore_lock`, and
  `let_underscore_must_use` from Clippy]
  (rust-lang/rust#97739)
- [Stabilize `break`ing from arbitrary labeled blocks ("label-break-value")]
  (rust-lang/rust#99332)
- [Uninitialized integers, floats, and raw pointers are now considered
  immediate UB](rust-lang/rust#98919).
  Usage of `MaybeUninit` is the correct way to work with uninitialized
  memory.
- [Stabilize raw-dylib for Windows x86_64, aarch64, and thumbv7a]
  (rust-lang/rust#99916)
- [Do not allow `Drop` impl on foreign ADTs]
  (rust-lang/rust#99576)

Compiler
--------
- [Stabilize -Csplit-debuginfo on Linux]
  (rust-lang/rust#98051)
- [Use niche-filling optimization even when multiple variants have
  data] (rust-lang/rust#94075)
- [Associated type projections are now verified to be well-formed
  prior to resolving the underlying type]
  (rust-lang/rust#99217)
- [Stringify non-shorthand visibility correctly]
  (rust-lang/rust#100350)
- [Normalize struct field types when unsizing]
  (rust-lang/rust#101831)
- [Update to LLVM 15](rust-lang/rust#99464)
- [Fix aarch64 call abi to correctly zeroext when needed]
  (rust-lang/rust#97800)
- [debuginfo: Generalize C++-like encoding for enums]
  (rust-lang/rust#98393)
- [Add `special_module_name` lint]
  (rust-lang/rust#94467)
- [Add support for generating unique profraw files by default when
  using `-C instrument-coverage`]
  (rust-lang/rust#100384)
- [Allow dynamic linking for iOS/tvOS targets]
  (rust-lang/rust#100636)

New targets:
- [Add armv4t-none-eabi as a tier 3 target]
  (rust-lang/rust#100244)
- [Add powerpc64-unknown-openbsd and riscv64-unknown-openbsd as tier 3 targets]
  (rust-lang/rust#101025)
- Refer to Rust's [platform support page][platform-support-doc] for more
  information on Rust's tiered platform support.

Libraries
---------
- [Don't generate `PartialEq::ne` in derive(PartialEq)]
  (rust-lang/rust#98655)
- [Windows RNG: Use `BCRYPT_RNG_ALG_HANDLE` by default]
  (rust-lang/rust#101325)
- [Forbid mixing `System` with direct system allocator calls]
  (rust-lang/rust#101394)
- [Document no support for writing to non-blocking stdio/stderr]
  (rust-lang/rust#101416)
- [`std::layout::Layout` size must not overflow `isize::MAX` when
  rounded up to `align`](rust-lang/rust#95295)
  This also changes the safety conditions on
  `Layout::from_size_align_unchecked`.

Stabilized APIs
---------------
- [`std::backtrace::Backtrace`]
  (https://doc.rust-lang.org/stable/std/backtrace/struct.Backtrace.html)
- [`Bound::as_ref`]
  (https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.as_ref)
- [`std::io::read_to_string`]
  (https://doc.rust-lang.org/stable/std/io/fn.read_to_string.html)
- [`<*const T>::cast_mut`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_mut)
- [`<*mut T>::cast_const`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.cast_const)

These APIs are now stable in const contexts:
- [`<*const T>::offset_from`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from)
- [`<*mut T>::offset_from`]
  (https://doc.rust-lang.org/stable/std/primitive.pointer.html#method.offset_from)

Cargo
-----
- [Apply GitHub fast path even for partial hashes]
  (rust-lang/cargo#10807)
- [Do not add home bin path to PATH if it's already there]
  (rust-lang/cargo#11023)
- [Take priority into account within the pending queue]
  (rust-lang/cargo#11032).
  This slightly optimizes job scheduling by Cargo, with typically
  small improvements on larger crate graph builds.

Compatibility Notes
-------------------
- [`std::layout::Layout` size must not overflow `isize::MAX` when
  rounded up to `align`] (rust-lang/rust#95295).
  This also changes the safety conditions on
  `Layout::from_size_align_unchecked`.
- [`PollFn` now only implements `Unpin` if the closure is `Unpin`]
  (rust-lang/rust#102737).
  This is a possible breaking change if users were relying on the
  blanket unpin implementation.  See discussion on the PR for
  details of why this change was made.
- [Drop ExactSizeIterator impl from std::char::EscapeAscii]
  (rust-lang/rust#99880)
  This is a backwards-incompatible change to the standard library's
  surface area, but is unlikely to affect real world usage.
- [Do not consider a single repeated lifetime eligible for elision
  in the return type] (rust-lang/rust#103450)
  This behavior was unintentionally changed in 1.64.0, and this
  release reverts that change by making this an error again.
- [Reenable disabled early syntax gates as future-incompatibility
  lints] (rust-lang/rust#99935)
- [Update the minimum external LLVM to 13]
  (rust-lang/rust#100460)
- [Don't duplicate file descriptors into stdio fds]
  (rust-lang/rust#101426)
- [Sunset RLS](rust-lang/rust#100863)
- [Deny usage of `#![cfg_attr(..., crate_type = ...)]` to set the
  crate type] (rust-lang/rust#99784)
  This strengthens the forward compatibility lint
  deprecated_cfg_attr_crate_type_name to deny.
- [`llvm-has-rust-patches` allows setting the build system to treat
  the LLVM as having Rust-specific patches]
  (rust-lang/rust#101072)
  This option may need to be set for distributions that are building
  Rust with a patched LLVM via `llvm-config`, not the built-in
  LLVM.

Internal Changes
----------------

These changes do not affect any public interfaces of Rust, but they represent
significant improvements to the performance or internals of rustc and related
tools.

- [Add `x.sh` and `x.ps1` shell scripts]
  (rust-lang/rust#99992)
- [compiletest: use target cfg instead of hard-coded tables]
  (rust-lang/rust#100260)
- [Use object instead of LLVM for reading bitcode from rlibs]
  (rust-lang/rust#98100)
- [Enable MIR inlining for optimized compilations]
  (rust-lang/rust#91743)
  This provides a 3-10% improvement in compiletimes for real world
  crates. See [perf results]
  (https://perf.rust-lang.org/compare.html?start=aedf78e56b2279cc869962feac5153b6ba7001ed&end=0075bb4fad68e64b6d1be06bf2db366c30bc75e1&stat=instructions:u).
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Uplift clippy::let_underscore_lock to rustc
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