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Associated functions that contain extern indicator or have #[rustc_std_internal_symbol] are reachable #86492

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merged 4 commits into from Aug 13, 2021

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ghost
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@ghost ghost commented Jun 20, 2021

Previously these fails to link with undefined reference to `foo':

Example 1
struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}

(Playground)

Example 2
#![crate_name = "lib"]
#![crate_type = "lib"]

struct AssocFn;

impl AssocFn {
    #[no_mangle]
    fn foo() {}
}
extern crate lib;

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}

But I believe they should link successfully, because this works:

#[no_mangle]
fn foo() {}

fn main() {
    extern "Rust" {
        fn foo();
    }
    unsafe { foo() }
}

(Playground)

This PR fixes the problem, by adding associated functions that have "custom linkage" to reachable_set, just like normal functions.

I haven't tested whether #76211 and Miri are fixed by this PR yet, but I'm submitting this anyway since this fixes the examples above.

I added a run-pass test that combines my two examples above, but I'm not sure if that's the right way to test this. Maybe I should add / modify an existing codegen test (src/test/codegen/export-no-mangle.rs?) instead?

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r? @petrochenkov

(rust-highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 20, 2021
@petrochenkov
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I don't think #[no_mangle] is supposed to work with associated functions at all.
Are there practical use cases / uses in the wild?

All the checks and logic mentioning sym::no_mangle that I can find in the compiler only apply to free items.

@petrochenkov petrochenkov added T-lang Relevant to the language team, which will review and decide on the PR/issue. S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 20, 2021
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I'm still not sure whether the label combination S-waiting-on-team + T-lang is enough for the lang team to triage a PR, so I'm going to nominate as well.

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ghost commented Jun 20, 2021

I don't think #[no_mangle] is supposed to work with associated functions at all.
Are there practical use cases / uses in the wild?

I don't know. I found it supported by reading this code. (EDIT: Never mind. That code does not seem very convincing.) I'm experimenting with it fully because I need to know whether Miri should support this: I found that it is working on public associated functions in library crates, and the unused_attributes lint is explicitly not fired for #[no_mangle] on associated functions:

Target::Static | Target::Fn | Target::Method(..) => {}

@crlf0710 crlf0710 added S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). and removed S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). labels Jul 9, 2021
@Mark-Simulacrum
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This was discussed during the last several language team meetings. There doesn't seem to be a lot of strong opinions in either direction on this, but the overall consensus seems to be that we should make #[no_mangle] work (i.e., produce a non-mangled symbol in the final binary, along with export/reachability) on functions inside impl Foo. This seems to be consistent with a general perspective that the context where a function is placed should not, generally, restrict what attributes can be placed on it so long as they are supportable in that context.

There was some debate over whether this is practically useful, but generally it seems like the answer is at least maybe yes - the description of #76211 cites a concrete case where this was unexpectedly not working, for example. Ultimately, it seems relatively harmless to support this, and fairly likely to do what users expect.


We did not discuss whether it makes sense to feature gate this to start -- I suspect that would in practice break some code in the wild, and this seems largely like a bugfix, so perhaps we will opt to skip that. In that case we'll want an FCP so I'll bring this up on Zulip so that someone on T-lang can hopefully kick that off.

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@rfcbot fcp merge

Per @Mark-Simulacrum's summary, I propose to merge this. I think we should skip the feature gate, as I consider this a bug fix.

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rfcbot commented Jul 23, 2021

Team member @nikomatsakis has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

@rfcbot rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Jul 23, 2021
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Sharing in case others have the same thought process:

At first I thought that it was odd to have a #[no_mangle] associated function use the fn <...> name, since I think of the name of those functions as including the type-component of the path. That is, I think of the function above as AssocFn::foo rather than a function named foo. However, the more I consider it, the more it makes sense to think of it just like we would mod assoc_fn { #[no_mangle] fn foo() { ... } }-- the type is part of the path / item container, just as any other path element such as a crate or module would be.

@rfcbot rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Jul 24, 2021
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rfcbot commented Jul 24, 2021

🔔 This is now entering its final comment period, as per the review above. 🔔

@Mark-Simulacrum Mark-Simulacrum added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). labels Aug 3, 2021
@rfcbot rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Aug 3, 2021
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rfcbot commented Aug 3, 2021

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

The RFC will be merged soon.

@rfcbot rfcbot added the to-announce Announce this issue on triage meeting label Aug 3, 2021
@petrochenkov
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If the intent is to support #[no_mangle] on associated items, then this PR is not enough.
You can search for sym::no_mangle in rustc codebase - all those places need to be updated to account for no_mangle on non-items.

@petrochenkov petrochenkov removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 4, 2021
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bors commented Aug 13, 2021

📌 Commit 9315a0c has been approved by petrochenkov

@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 Aug 13, 2021
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bors commented Aug 13, 2021

⌛ Testing commit 9315a0c with merge 3266d01a40ef990ea7c029906fed132f9d2e4f8e...

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bors commented Aug 13, 2021

💔 Test failed - checks-actions

@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 13, 2021
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A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

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@bors retry

@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 Aug 13, 2021
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bors commented Aug 13, 2021

⌛ Testing commit 9315a0c with merge 5a19ffe...

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bors commented Aug 13, 2021

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 5a19ffe to master...

@bors bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 13, 2021
@bors bors merged commit 5a19ffe into rust-lang:master Aug 13, 2021
@rustbot rustbot added this to the 1.56.0 milestone Aug 13, 2021
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📣 Toolstate changed by #86492!

Tested on commit 5a19ffe.
Direct link to PR: #86492

💔 miri on windows: test-pass → test-fail (cc @eddyb @RalfJung @oli-obk).
💔 miri on linux: test-pass → test-fail (cc @eddyb @RalfJung @oli-obk).

rust-highfive added a commit to rust-lang-nursery/rust-toolstate that referenced this pull request Aug 13, 2021
Tested on commit rust-lang/rust@5a19ffe.
Direct link to PR: <rust-lang/rust#86492>

💔 miri on windows: test-pass → test-fail (cc @eddyb @RalfJung @oli-obk).
💔 miri on linux: test-pass → test-fail (cc @eddyb @RalfJung @oli-obk).
@ghost ghost deleted the no-mangle-method branch August 14, 2021 10:29
Comment on lines -214 to +222
if let Node::Item(item) = *node {
let reachable = if let hir::ItemKind::Fn(ref sig, ..) = item.kind {
sig.header.abi != Abi::Rust
} else {
false
};
let codegen_attrs = self.tcx.codegen_fn_attrs(item.def_id);
if let Node::Item(hir::Item { kind: hir::ItemKind::Fn(sig, ..), def_id, .. })
| Node::ImplItem(hir::ImplItem {
kind: hir::ImplItemKind::Fn(sig, ..),
def_id,
..
}) = *node
{
let reachable = sig.header.abi != Abi::Rust;
let codegen_attrs = self.tcx.codegen_fn_attrs(*def_id);
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I think this change (unintentionally) made reachable_set no longer include any #[no_mangle] static item. Opened #88032 to fix this.

bors added a commit to rust-lang/miri that referenced this pull request Aug 15, 2021
Update tests for `#[no_mangle]` on associated functions

rust-lang/rust#86492 has landed:
- The code in #1837 starts to work (even without `AssocFn::foo();` at line 12) in Miri.
- `pub` is not necessary for `#[no_mangle]` associated functions in `test-cargo-miri/exported-symbol-dep/src/lib.rs` anymore.

Closes #1837.
camsteffen added a commit to camsteffen/rust that referenced this pull request Aug 15, 2021
…enkov

Fix `reachable_set` for non-function items in non-library crates

I unintentionally changed `reachable_set` to ignore non-function items when `!self.any_library` in rust-lang#86492, which can lead to "undefined reference" errors in non-library (`cdylib`/`staticlib`/`bin`) crates, for example: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=6bb2c5065a9be7e40943d0541e161b5a

This PR restores the behavior of `reachable_set` for non-function items.

Fixes rust-lang#88016.

<details>
<summary>The modified test will fail with this output without the `reachable_set` change</summary>

```
---- [codegen] codegen/external-no-mangle-statics.rs#staticlib stdout ----

error in revision `staticlib`: verification with 'FileCheck' failed
status: exit status: 1
command: "/checkout/build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" "--input-file" "/checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll" "/checkout/src/test/codegen/external-no-mangle-statics.rs" "--check-prefixes" "CHECK,NONMSVC,staticlib"
stdout:
------------------------------------------

------------------------------------------
stderr:
------------------------------------------
/checkout/src/test/codegen/external-no-mangle-statics.rs:10:11: error: CHECK: expected string not found in input
// CHECK: `@A` = local_unnamed_addr constant
          ^
/checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll:1:1: note: scanning from here
; ModuleID = 'external_no_mangle_statics.b50529d3-cgu.0'
^
/checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll:1:6: note: possible intended match here
; ModuleID = 'external_no_mangle_statics.b50529d3-cgu.0'
     ^

Input file: /checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll
Check file: /checkout/src/test/codegen/external-no-mangle-statics.rs

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            1: ; ModuleID = 'external_no_mangle_statics.b50529d3-cgu.0'
check:10'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
check:10'1          ?                                                   possible intended match
            2: source_filename = "external_no_mangle_statics.b50529d3-cgu.0"
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            3: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            4: target triple = "x86_64-unknown-linux-gnu"
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            5:
check:10'0     ~
            6: !llvm.module.flags = !{!0, !1}
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            .
            .
            .
>>>>>>

------------------------------------------

failures:
    [codegen] codegen/external-no-mangle-statics.rs#staticlib
```
</details>
bors added a commit to rust-lang-ci/rust that referenced this pull request Aug 16, 2021
Fix `reachable_set` for non-function items in non-library crates

I unintentionally changed `reachable_set` to ignore non-function items when `!self.any_library` in rust-lang#86492, which can lead to "undefined reference" errors in non-library (`cdylib`/`staticlib`/`bin`) crates, for example: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=6bb2c5065a9be7e40943d0541e161b5a

This PR restores the behavior of `reachable_set` for non-function items.

Fixes rust-lang#88016.

<details>
<summary>The modified test will fail with this output without the `reachable_set` change</summary>

```
---- [codegen] codegen/external-no-mangle-statics.rs#staticlib stdout ----

error in revision `staticlib`: verification with 'FileCheck' failed
status: exit status: 1
command: "/checkout/build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" "--input-file" "/checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll" "/checkout/src/test/codegen/external-no-mangle-statics.rs" "--check-prefixes" "CHECK,NONMSVC,staticlib"
stdout:
------------------------------------------

------------------------------------------
stderr:
------------------------------------------
/checkout/src/test/codegen/external-no-mangle-statics.rs:10:11: error: CHECK: expected string not found in input
// CHECK: `@A` = local_unnamed_addr constant
          ^
/checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll:1:1: note: scanning from here
; ModuleID = 'external_no_mangle_statics.b50529d3-cgu.0'
^
/checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll:1:6: note: possible intended match here
; ModuleID = 'external_no_mangle_statics.b50529d3-cgu.0'
     ^

Input file: /checkout/build/x86_64-unknown-linux-gnu/test/codegen/external-no-mangle-statics.staticlib/external-no-mangle-statics.ll
Check file: /checkout/src/test/codegen/external-no-mangle-statics.rs

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            1: ; ModuleID = 'external_no_mangle_statics.b50529d3-cgu.0'
check:10'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
check:10'1          ?                                                   possible intended match
            2: source_filename = "external_no_mangle_statics.b50529d3-cgu.0"
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            3: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            4: target triple = "x86_64-unknown-linux-gnu"
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            5:
check:10'0     ~
            6: !llvm.module.flags = !{!0, !1}
check:10'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            .
            .
            .
>>>>>>

------------------------------------------

failures:
    [codegen] codegen/external-no-mangle-statics.rs#staticlib
```
</details>
wip-sync pushed a commit to NetBSD/pkgsrc-wip that referenced this pull request Oct 22, 2021
Pkgsrc changes:
 * Remove one now-longer-applicable patch, adjust a few others
 * Bump bootstrap requirements to 1.55.0.

Upstream changes:

Version 1.56.0 (2021-10-21)
========================

Language
--------

- [The 2021 Edition is now stable.][rust#88100]
  See [the edition guide][rust-2021-edition-guide] for more details.
- [The pattern in `binding @ pattern` can now also introduce new bindings.]
  [rust#85305]
- [Union field access is permitted in `const fn`.][rust#85769]

[rust-2021-edition-guide]: https://doc.rust-lang.org/nightly/edition-guide/rust-2021/index.html

Compiler
--------

- [Upgrade to LLVM 13.][rust#87570]
- [Support memory, address, and thread sanitizers on
  aarch64-unknown-freebsd.][rust#88023]
- [Allow specifying a deployment target version for all iOS targets][rust#87699]
- [Warnings can be forced on with `--force-warn`.][rust#87472]
  This feature is primarily intended for usage by `cargo fix`,
  rather than end users.
- [Promote `aarch64-apple-ios-sim` to Tier 2\*.][rust#87760]
- [Add `powerpc-unknown-freebsd` at Tier 3\*.][rust#87370]
- [Add `riscv32imc-esp-espidf` at Tier 3\*.][rust#87666]

\* Refer to Rust's [platform support page][platform-support-doc] for more
information on Rust's tiered platform support.

Libraries
---------

- [Allow writing of incomplete UTF-8 sequences via stdout/stderr on Windows.]
  [rust#83342]
  The Windows console still requires valid Unicode, but this change allows
  splitting a UTF-8 character across multiple write calls. This allows, for
  instance, programs that just read and write data buffers (e.g. copying a file
  to stdout) without regard for Unicode or character boundaries.
- [Prefer `AtomicU{64,128}` over Mutex for Instant backsliding protection.]
  [rust#83093]
  For this use case, atomics scale much better under contention.
- [Implement `Extend<(A, B)>` for `(Extend<A>, Extend<B>)`][rust#85835]
- [impl Default, Copy, Clone for std::io::Sink and std::io::Empty][rust#86744]
- [`impl From<[(K, V); N]>` for all collections.][rust#84111]
- [Remove `P: Unpin` bound on impl Future for Pin.][rust#81363]
- [Treat invalid environment variable names as non-existent.][rust#86183]
  Previously, the environment functions would panic if given a
  variable name with an internal null character or equal sign (`=`).
  Now, these functions will just treat such names as non-existent
  variables, since the OS cannot represent the existence of a
  variable with such a name.

Stabilised APIs
---------------

- [`std::os::unix::fs::chroot`]
- [`UnsafeCell::raw_get`]
- [`BufWriter::into_parts`]
- [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]
  These APIs were previously stable in `std`, but are now also available
  in `core`.
- [`Vec::shrink_to`]
- [`String::shrink_to`]
- [`OsString::shrink_to`]
- [`PathBuf::shrink_to`]
- [`BinaryHeap::shrink_to`]
- [`VecDeque::shrink_to`]
- [`HashMap::shrink_to`]
- [`HashSet::shrink_to`]

These APIs are now usable in const contexts:

- [`std::mem::transmute`]
- [`[T]::first`][`slice::first`]
- [`[T]::split_first`][`slice::split_first`]
- [`[T]::last`][`slice::last`]
- [`[T]::split_last`][`slice::split_last`]

Cargo
-----

- [Cargo supports specifying a minimum supported Rust version in Cargo.toml.]
  [`rust-version`] This has no effect at present on dependency
  version selection.  We encourage crates to specify their minimum
  supported Rust version, and we encourage CI systems that support
  Rust code to include a crate's specified minimum version in the
  text matrix for that crate by default.

Compatibility notes
-------------------

- [Update to new argument parsing rules on Windows.][rust#87580]
  This adjusts Rust's standard library to match the behavior of the standard
  libraries for C/C++. The rules have changed slightly over time, and this PR
  brings us to the latest set of rules (changed in 2008).
- [Disallow the aapcs calling convention on aarch64][rust#88399]
  This was already not supported by LLVM; this change surfaces this lack of
  support with a better error message.
- [Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default][rust#87385]
- [Warn when an escaped newline skips multiple lines.][rust#87671]
- [Calls to `libc::getpid` / `std::process::id` from `Command::pre_exec`
  may return different values on glibc <= 2.24.][rust#81825] Rust
  now invokes the `clone3` system call directly, when available,
  to use new functionality available via that system call. Older
  versions of glibc cache the result of `getpid`, and only update
  that cache when calling glibc's clone/fork functions, so a direct
  system call bypasses that cache update. glibc 2.25 and newer no
  longer cache `getpid` for exactly this reason.

Internal changes
----------------
These changes provide no direct user facing benefits, but represent
significant improvements to the internals and overall performance
of rustc and related tools.

- [LLVM is compiled with PGO in published x86_64-unknown-linux-gnu
  artifacts.][rust#88069] This improves the performance of most Rust builds.

- [Unify representation of macros in internal data structures.][rust#88019]
  This change fixes a host of bugs with the handling of macros by the compiler,
  as well as rustdoc.

[`std::os::unix::fs::chroot`]: https://doc.rust-lang.org/stable/std/os/unix/fs/fn.chroot.html
[`Iterator::intersperse`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse
[`Iterator::intersperse_with`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse
[`UnsafeCell::raw_get`]: https://doc.rust-lang.org/stable/std/cell/struct.UnsafeCell.html#method.raw_get
[`BufWriter::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.BufWriter.html#method.into_parts
[`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]: rust-lang/rust#84662
[`Vec::shrink_to`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.shrink_to
[`String::shrink_to`]: https://doc.rust-lang.org/stable/std/string/struct.String.html#method.shrink_to
[`OsString::shrink_to`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.shrink_to
[`PathBuf::shrink_to`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.shrink_to
[`BinaryHeap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.shrink_to
[`VecDeque::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.shrink_to
[`HashMap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_map/struct.HashMap.html#method.shrink_to
[`HashSet::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_set/struct.HashSet.html#method.shrink_to
[`std::mem::transmute`]: https://doc.rust-lang.org/stable/std/mem/fn.transmute.html
[`slice::first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first
[`slice::split_first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first
[`slice::last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last
[`slice::split_last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last
[`rust-version`]: https://doc.rust-lang.org/nightly/cargo/reference/manifest.html#the-rust-version-field
[rust#87671]: rust-lang/rust#87671
[rust#86183]: rust-lang/rust#86183
[rust#87385]: rust-lang/rust#87385
[rust#88100]: rust-lang/rust#88100
[rust#86860]: rust-lang/rust#86860
[rust#84039]: rust-lang/rust#84039
[rust#86492]: rust-lang/rust#86492
[rust#88363]: rust-lang/rust#88363
[rust#85305]: rust-lang/rust#85305
[rust#87832]: rust-lang/rust#87832
[rust#88069]: rust-lang/rust#88069
[rust#87472]: rust-lang/rust#87472
[rust#87699]: rust-lang/rust#87699
[rust#87570]: rust-lang/rust#87570
[rust#88023]: rust-lang/rust#88023
[rust#87760]: rust-lang/rust#87760
[rust#87370]: rust-lang/rust#87370
[rust#87580]: rust-lang/rust#87580
[rust#83342]: rust-lang/rust#83342
[rust#83093]: rust-lang/rust#83093
[rust#88177]: rust-lang/rust#88177
[rust#88548]: rust-lang/rust#88548
[rust#88551]: rust-lang/rust#88551
[rust#88299]: rust-lang/rust#88299
[rust#88220]: rust-lang/rust#88220
[rust#85835]: rust-lang/rust#85835
[rust#86879]: rust-lang/rust#86879
[rust#86744]: rust-lang/rust#86744
[rust#84662]: rust-lang/rust#84662
[rust#86593]: rust-lang/rust#86593
[rust#81050]: rust-lang/rust#81050
[rust#81363]: rust-lang/rust#81363
[rust#84111]: rust-lang/rust#84111
[rust#85769]: rust-lang/rust#85769 (comment)
[rust#88490]: rust-lang/rust#88490
[rust#88269]: rust-lang/rust#88269
[rust#84176]: rust-lang/rust#84176
[rust#88399]: rust-lang/rust#88399
[rust#88227]: rust-lang/rust#88227
[rust#88200]: rust-lang/rust#88200
[rust#82776]: rust-lang/rust#82776
[rust#88077]: rust-lang/rust#88077
[rust#87728]: rust-lang/rust#87728
[rust#87050]: rust-lang/rust#87050
[rust#87619]: rust-lang/rust#87619
[rust#81825]: rust-lang/rust#81825 (comment)
[rust#88019]: rust-lang/rust#88019
[rust#87666]: rust-lang/rust#87666
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Nov 20, 2021
Pkgsrc changes:
 * Bump bootstrap kit version to 1.55.0.
 * Adjust patches as needed, some no longer apply (so removed)
 * Update checksum adjustments.
 * Avoid rust-llvm on SunOS
 * Optionally build docs
 * Remove reference to closed/old PR#54621

Upstream changes:

Version 1.56.1 (2021-11-01)
===========================

- New lints to detect the presence of bidirectional-override Unicode
  codepoints in the compiled source code ([CVE-2021-42574])

[CVE-2021-42574]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-42574

Version 1.56.0 (2021-10-21)
========================

Language
--------

- [The 2021 Edition is now stable.][rust#88100]
  See [the edition guide][rust-2021-edition-guide] for more details.
- [The pattern in `binding @ pattern` can now also introduce new bindings.]
  [rust#85305]
- [Union field access is permitted in `const fn`.][rust#85769]

[rust-2021-edition-guide]:
  https://doc.rust-lang.org/nightly/edition-guide/rust-2021/index.html

Compiler
--------

- [Upgrade to LLVM 13.][rust#87570]
- [Support memory, address, and thread sanitizers on aarch64-unknown-freebsd.]
  [rust#88023]
- [Allow specifying a deployment target version for all iOS targets][rust#87699]
- [Warnings can be forced on with `--force-warn`.][rust#87472]
  This feature is primarily intended for usage by `cargo fix`, rather than
  end users.
- [Promote `aarch64-apple-ios-sim` to Tier 2\*.][rust#87760]
- [Add `powerpc-unknown-freebsd` at Tier 3\*.][rust#87370]
- [Add `riscv32imc-esp-espidf` at Tier 3\*.][rust#87666]

\* Refer to Rust's [platform support page][platform-support-doc] for more
information on Rust's tiered platform support.

Libraries
---------

- [Allow writing of incomplete UTF-8 sequences via stdout/stderr on Windows.]
  [rust#83342]
  The Windows console still requires valid Unicode, but this change allows
  splitting a UTF-8 character across multiple write calls. This allows, for
  instance, programs that just read and write data buffers (e.g. copying a file
  to stdout) without regard for Unicode or character boundaries.
- [Prefer `AtomicU{64,128}` over Mutex for Instant backsliding protection.]
  [rust#83093]
  For this use case, atomics scale much better under contention.
- [Implement `Extend<(A, B)>` for `(Extend<A>, Extend<B>)`][rust#85835]
- [impl Default, Copy, Clone for std::io::Sink and std::io::Empty][rust#86744]
- [`impl From<[(K, V); N]>` for all collections.][rust#84111]
- [Remove `P: Unpin` bound on impl Future for Pin.][rust#81363]
- [Treat invalid environment variable names as non-existent.][rust#86183]
  Previously, the environment functions would panic if given a
  variable name with an internal null character or equal sign (`=`).
  Now, these functions will just treat such names as non-existent
  variables, since the OS cannot represent the existence of a
  variable with such a name.

Stabilised APIs
---------------

- [`std::os::unix::fs::chroot`]
- [`UnsafeCell::raw_get`]
- [`BufWriter::into_parts`]
- [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]
  These APIs were previously stable in `std`, but are now also available
  in `core`.
- [`Vec::shrink_to`]
- [`String::shrink_to`]
- [`OsString::shrink_to`]
- [`PathBuf::shrink_to`]
- [`BinaryHeap::shrink_to`]
- [`VecDeque::shrink_to`]
- [`HashMap::shrink_to`]
- [`HashSet::shrink_to`]

These APIs are now usable in const contexts:

- [`std::mem::transmute`]
- [`[T]::first`][`slice::first`]
- [`[T]::split_first`][`slice::split_first`]
- [`[T]::last`][`slice::last`]
- [`[T]::split_last`][`slice::split_last`]

Cargo
-----

- [Cargo supports specifying a minimum supported Rust version in Cargo.toml.]
  [`rust-version`]
  This has no effect at present on dependency version selection.
  We encourage crates to specify their minimum supported Rust
  version, and we encourage CI systems that support Rust code to
  include a crate's specified minimum version in the text matrix
  for that crate by default.

Compatibility notes
-------------------

- [Update to new argument parsing rules on Windows.][rust#87580]
  This adjusts Rust's standard library to match the behavior of the standard
  libraries for C/C++. The rules have changed slightly over time, and this PR
  brings us to the latest set of rules (changed in 2008).
- [Disallow the aapcs calling convention on aarch64][rust#88399]
  This was already not supported by LLVM; this change surfaces this lack of
  support with a better error message.
- [Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default][rust#87385]
- [Warn when an escaped newline skips multiple lines.][rust#87671]
- [Calls to `libc::getpid` / `std::process::id` from `Command::pre_exec`
  may return different values on glibc <= 2.24.][rust#81825]
  Rust now invokes the `clone3` system call directly, when available,
  to use new functionality available via that system call. Older
  versions of glibc cache the result of `getpid`, and only update
  that cache when calling glibc's clone/fork functions, so a direct
  system call bypasses that cache update. glibc 2.25 and newer no
  longer cache `getpid` for exactly this reason.

Internal changes
----------------
These changes provide no direct user facing benefits, but represent
significant improvements to the internals and overall performance
of rustc and related tools.

- [LLVM is compiled with PGO in published x86_64-unknown-linux-gnu artifacts.]
  [rust#88069]
  This improves the performance of most Rust builds.
- [Unify representation of macros in internal data structures.][rust#88019]
  This change fixes a host of bugs with the handling of macros by the compiler,
  as well as rustdoc.

[`std::os::unix::fs::chroot`]: https://doc.rust-lang.org/stable/std/os/unix/fs/fn.chroot.html
[`Iterator::intersperse`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse
[`Iterator::intersperse_with`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse
[`UnsafeCell::raw_get`]: https://doc.rust-lang.org/stable/std/cell/struct.UnsafeCell.html#method.raw_get
[`BufWriter::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.BufWriter.html#method.into_parts
[`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]: rust-lang/rust#84662
[`Vec::shrink_to`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.shrink_to
[`String::shrink_to`]: https://doc.rust-lang.org/stable/std/string/struct.String.html#method.shrink_to
[`OsString::shrink_to`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.shrink_to
[`PathBuf::shrink_to`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.shrink_to
[`BinaryHeap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.shrink_to
[`VecDeque::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.shrink_to
[`HashMap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_map/struct.HashMap.html#method.shrink_to
[`HashSet::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_set/struct.HashSet.html#method.shrink_to
[`std::mem::transmute`]: https://doc.rust-lang.org/stable/std/mem/fn.transmute.html
[`slice::first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first
[`slice::split_first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first
[`slice::last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last
[`slice::split_last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last
[`rust-version`]: https://doc.rust-lang.org/nightly/cargo/reference/manifest.html#the-rust-version-field
[rust#87671]: rust-lang/rust#87671
[rust#86183]: rust-lang/rust#86183
[rust#87385]: rust-lang/rust#87385
[rust#88100]: rust-lang/rust#88100
[rust#86860]: rust-lang/rust#86860
[rust#84039]: rust-lang/rust#84039
[rust#86492]: rust-lang/rust#86492
[rust#88363]: rust-lang/rust#88363
[rust#85305]: rust-lang/rust#85305
[rust#87832]: rust-lang/rust#87832
[rust#88069]: rust-lang/rust#88069
[rust#87472]: rust-lang/rust#87472
[rust#87699]: rust-lang/rust#87699
[rust#87570]: rust-lang/rust#87570
[rust#88023]: rust-lang/rust#88023
[rust#87760]: rust-lang/rust#87760
[rust#87370]: rust-lang/rust#87370
[rust#87580]: rust-lang/rust#87580
[rust#83342]: rust-lang/rust#83342
[rust#83093]: rust-lang/rust#83093
[rust#88177]: rust-lang/rust#88177
[rust#88548]: rust-lang/rust#88548
[rust#88551]: rust-lang/rust#88551
[rust#88299]: rust-lang/rust#88299
[rust#88220]: rust-lang/rust#88220
[rust#85835]: rust-lang/rust#85835
[rust#86879]: rust-lang/rust#86879
[rust#86744]: rust-lang/rust#86744
[rust#84662]: rust-lang/rust#84662
[rust#86593]: rust-lang/rust#86593
[rust#81050]: rust-lang/rust#81050
[rust#81363]: rust-lang/rust#81363
[rust#84111]: rust-lang/rust#84111
[rust#85769]: rust-lang/rust#85769 (comment)
[rust#88490]: rust-lang/rust#88490
[rust#88269]: rust-lang/rust#88269
[rust#84176]: rust-lang/rust#84176
[rust#88399]: rust-lang/rust#88399
[rust#88227]: rust-lang/rust#88227
[rust#88200]: rust-lang/rust#88200
[rust#82776]: rust-lang/rust#82776
[rust#88077]: rust-lang/rust#88077
[rust#87728]: rust-lang/rust#87728
[rust#87050]: rust-lang/rust#87050
[rust#87619]: rust-lang/rust#87619
[rust#81825]: rust-lang/rust#81825 (comment)
[rust#88019]: rust-lang/rust#88019
[rust#87666]: rust-lang/rust#87666

Version 1.55.0 (2021-09-09)
============================

Language
--------
- [You can now write open "from" range patterns (`X..`), which will start
  at `X` and will end at the maximum value of the integer.][83918]
- [You can now explicitly import the prelude of different editions
  through `std::prelude` (e.g. `use std::prelude::rust_2021::*;`).][86294]

Compiler
--------
- [Added tier 3\* support for `powerpc64le-unknown-freebsd`.][83572]

\* Refer to Rust's [platform support page][platform-support-doc] for more
   information on Rust's tiered platform support.

Libraries
---------

- [Updated std's float parsing to use the Eisel-Lemire algorithm.][86761]
  These improvements should in general provide faster string parsing of floats,
  no longer reject certain valid floating point values, and reduce
  the produced code size for non-stripped artifacts.
- [`string::Drain` now implements `AsRef<str>` and `AsRef<[u8]>`.][86858]

Stabilised APIs
---------------

- [`Bound::cloned`]
- [`Drain::as_str`]
- [`IntoInnerError::into_error`]
- [`IntoInnerError::into_parts`]
- [`MaybeUninit::assume_init_mut`]
- [`MaybeUninit::assume_init_ref`]
- [`MaybeUninit::write`]
- [`array::map`]
- [`ops::ControlFlow`]
- [`x86::_bittest`]
- [`x86::_bittestandcomplement`]
- [`x86::_bittestandreset`]
- [`x86::_bittestandset`]
- [`x86_64::_bittest64`]
- [`x86_64::_bittestandcomplement64`]
- [`x86_64::_bittestandreset64`]
- [`x86_64::_bittestandset64`]

The following previously stable functions are now `const`.

- [`str::from_utf8_unchecked`]


Cargo
-----
- [Cargo will now deduplicate compiler diagnostics to the terminal when invoking
  rustc in parallel such as when using `cargo test`.][cargo/9675]
- [The package definition in `cargo metadata` now includes the `"default_run"`
  field from the manifest.][cargo/9550]
- [Added `cargo d` as an alias for `cargo doc`.][cargo/9680]
- [Added `{lib}` as formatting option for `cargo tree` to print the `"lib_name"`
  of packages.][cargo/9663]

Rustdoc
-------
- [Added "Go to item on exact match" search option.][85876]
- [The "Implementors" section on traits no longer shows redundant
  method definitions.][85970]
- [Trait implementations are toggled open by default.][86260] This should
  make the implementations more searchable by tools like `CTRL+F` in
  your browser.
- [Intra-doc links should now correctly resolve associated items (e.g. methods)
  through type aliases.][86334]
- [Traits which are marked with `#[doc(hidden)]` will no longer appear in the
  "Trait Implementations" section.][86513]


Compatibility Notes
-------------------
- [std functions that return an `io::Error` will no longer use the
  `ErrorKind::Other` variant.][85746] This is to better reflect that these
  kinds of errors could be categorised [into newer more specific `ErrorKind`
  variants][79965], and that they do not represent a user error.
- [Using environment variable names with `process::Command` on Windows now
  behaves as expected.][85270] Previously using envionment variables with
  `Command` would cause them to be ASCII-uppercased.
- [Rustdoc will now warn on using rustdoc lints that aren't prefixed
  with `rustdoc::`][86849]

[86849]: rust-lang/rust#86849
[86513]: rust-lang/rust#86513
[86334]: rust-lang/rust#86334
[86260]: rust-lang/rust#86260
[85970]: rust-lang/rust#85970
[85876]: rust-lang/rust#85876
[83572]: rust-lang/rust#83572
[86294]: rust-lang/rust#86294
[86858]: rust-lang/rust#86858
[86761]: rust-lang/rust#86761
[85769]: rust-lang/rust#85769
[85746]: rust-lang/rust#85746
[85305]: rust-lang/rust#85305
[85270]: rust-lang/rust#85270
[84111]: rust-lang/rust#84111
[83918]: rust-lang/rust#83918
[79965]: rust-lang/rust#79965
[87370]: rust-lang/rust#87370
[87298]: rust-lang/rust#87298
[cargo/9663]: rust-lang/cargo#9663
[cargo/9675]: rust-lang/cargo#9675
[cargo/9550]: rust-lang/cargo#9550
[cargo/9680]: rust-lang/cargo#9680
[cargo/9663]: rust-lang/cargo#9663
[`array::map`]: https://doc.rust-lang.org/stable/std/primitive.array.html#method.map
[`Bound::cloned`]: https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.cloned
[`Drain::as_str`]: https://doc.rust-lang.org/stable/std/string/struct.Drain.html#method.as_str
[`IntoInnerError::into_error`]: https://doc.rust-lang.org/stable/std/io/struct.IntoInnerError.html#method.into_error
[`IntoInnerError::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.IntoInnerError.html#method.into_parts
[`MaybeUninit::assume_init_mut`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_mut
[`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref
[`MaybeUninit::write`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.write
[`Seek::rewind`]: https://doc.rust-lang.org/stable/std/io/trait.Seek.html#method.rewind
[`ops::ControlFlow`]: https://doc.rust-lang.org/stable/std/ops/enum.ControlFlow.html
[`str::from_utf8_unchecked`]: https://doc.rust-lang.org/stable/std/str/fn.from_utf8_unchecked.html
[`x86::_bittest`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittest.html
[`x86::_bittestandcomplement`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandcomplement.html
[`x86::_bittestandreset`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandreset.html
[`x86::_bittestandset`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandset.html
[`x86_64::_bittest64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittest64.html
[`x86_64::_bittestandcomplement64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandcomplement64.html
[`x86_64::_bittestandreset64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandreset64.html
[`x86_64::_bittestandset64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandset64.html
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