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Stabilize cache-messages #7450

Merged
merged 1 commit into from Oct 15, 2019
Merged

Stabilize cache-messages #7450

merged 1 commit into from Oct 15, 2019

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@ehuss
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ehuss commented Sep 27, 2019

This stabilizes the -Zcache-messages feature, making it always enabled.

What is stabilized?

This feature is intended to redisplay previous warnings on a "fresh" build instead of displaying no output.

Users have occasionally indicated frustration when they know there are warnings, but no output is displayed when the build is fresh. This also improves the interaction between cargo check and cargo clippy-preview. This also simplifies the code, and opens more possibilities for rustc to send side-channel messages to Cargo.

Cargo will now use JSON output from rustc and rustdoc 100% of the time (rustdoc --test does not use JSON). Previously Cargo would only use JSON for pipelined crates.

Cargo will save the JSON output into a file named output in the .fingerprint directory. This file is only created when the compiler outputs a diagnostic message.

If a crate is being recompiled, and Cargo considers it to be "fresh", it will replay the output file to the console.

Notable changes in this PR

  • Fixed a bug where replays were erroneously including pipeline rmeta artifact json messages.
  • clippy-preview is now included in the metadata hash, to force its artifacts to be separate from cargo check.
  • clippy-preview is no longer force-enabled, under the assumption that caching and fingerprinting is accurate, and the cached messages will be replayed.
  • clippy-preview's arguments are included in the fingerprint now that it is not force-enabled.
  • Rustdoc colors and short messages were fixed when pipelining was stabilized, so updated tests.

Closes #6986
Closes #6848
Closes #6664
Closes #2458

Concerns

The only notable issue with this is that switching between short and long human messages only replays the format from the first invocation. That is, if you do cargo build and it generates warnings, then running again with --message-format=short will still show the full length human messages. I'm personally fine with that behavior, even though it is not ideal. I think this feature overall improves the situation (where before no output was displayed). Being able to re-render between short/long is a very difficult problem, and unlikely to be fixable in the foreseeable future.

There was some concern expressed about being able to disable this. I think that would only be necessary if a severe bug is discovered. I do not feel that this change is risky enough to warrant a configurable option. If it does cause a problem, it can be quickly reverted with a one-line change to set OutputOptions::cache_cell to None. Since pipelining has been using JSON output for a while now without complaints, I feel pretty confident in it.

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rust-highfive commented Sep 27, 2019

r? @alexcrichton

(rust_highfive has picked a reviewer for you, use r? to override)

@ehuss ehuss force-pushed the ehuss:stabilize-cache-messages branch from 5bd089d to da5d65a Sep 27, 2019
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alexcrichton commented Sep 27, 2019

@rfcbot fcp merge

This all looks great to me, thanks @ehuss for pushing on this! Since it's a pretty big behavior change in rustc I'm just gonna confirm with fcp merge here.

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rfcbot commented Sep 27, 2019

Team member @alexcrichton 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.

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bors commented Sep 30, 2019

☔️ The latest upstream changes (presumably #6989) made this pull request unmergeable. Please resolve the merge conflicts.

@ehuss ehuss force-pushed the ehuss:stabilize-cache-messages branch from da5d65a to bd73e8d Sep 30, 2019
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rfcbot commented Sep 30, 2019

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

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rfcbot commented Oct 10, 2019

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.

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alexcrichton commented Oct 15, 2019

@bors: r+

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bors commented Oct 15, 2019

📌 Commit bd73e8d has been approved by alexcrichton

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bors commented Oct 15, 2019

⌛️ Testing commit bd73e8d with merge b03182a...

bors added a commit that referenced this pull request Oct 15, 2019
Stabilize cache-messages

This stabilizes the -Zcache-messages feature, making it always enabled.

## What is stabilized?

This feature is intended to redisplay previous warnings on a "fresh" build instead of displaying no output.

Users have occasionally indicated frustration when they know there are warnings, but no output is displayed when the build is fresh. This also improves the interaction between `cargo check` and `cargo clippy-preview`. This also simplifies the code, and opens more possibilities for `rustc` to send side-channel messages to Cargo.

Cargo will now use JSON output from `rustc` and `rustdoc` 100% of the time (`rustdoc --test` does not use JSON). Previously Cargo would only use JSON for pipelined crates.

Cargo will save the JSON output into a file named `output` in the `.fingerprint` directory. This file is only created when the compiler outputs a diagnostic message.

If a crate is being recompiled, and Cargo considers it to be "fresh", it will replay the output file to the console.

## Notable changes in this PR

- Fixed a bug where replays were erroneously including pipeline rmeta artifact json messages.
- clippy-preview is now included in the metadata hash, to force its artifacts to be separate from `cargo check`.
- clippy-preview is no longer force-enabled, under the assumption that caching and fingerprinting is accurate, and the cached messages will be replayed.
- clippy-preview's arguments are included in the fingerprint now that it is not force-enabled.
- Rustdoc colors and short messages were fixed when pipelining was stabilized, so updated tests.

Closes #6986
Closes #6848
Closes #6664
Closes #2458

## Concerns

The only notable issue with this is that switching between short and long human messages only replays the format from the first invocation.  That is, if you do `cargo build` and it generates warnings, then running again with `--message-format=short` will still show the full length human messages. I'm personally fine with that behavior, even though it is not ideal. I think this feature overall improves the situation (where before *no* output was displayed). Being able to re-render between short/long is a very difficult problem, and unlikely to be fixable in the foreseeable future.

There was some concern expressed about being able to disable this. I think that would only be necessary if a severe bug is discovered. I do not feel that this change is risky enough to warrant a configurable option. If it does cause a problem, it can be quickly reverted with a one-line change to set `OutputOptions::cache_cell` to `None`. Since pipelining has been using JSON output for a while now without complaints, I feel pretty confident in it.
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bors commented Oct 15, 2019

☀️ Test successful - checks-azure
Approved by: alexcrichton
Pushing b03182a to master...

@bors bors merged commit bd73e8d into rust-lang:master Oct 15, 2019
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@ehuss ehuss mentioned this pull request Oct 15, 2019
@apiraino apiraino mentioned this pull request Oct 15, 2019
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bors added a commit to rust-lang/rust that referenced this pull request Oct 16, 2019
Update cargo, cc, books

Update `cc` to include new parallel building support.

## nomicon

3 commits in 4374786f0b4bf0606b35d5c30a9681f342e5707b..5004ad30d69f93553ceef74439fea2159d1f769e
2019-09-17 18:33:21 +0200 to 2019-10-12 19:52:40 +0200
- further clarify C11 and C/C++11 terminology (rust-lang/nomicon#169)
- atomics: C11 -> C++20 (rust-lang/nomicon#168)
- use sound/unsound terminology

## cargo

12 commits in a429e8cc4614a46a86322a0777a477e2baa83f1c..3a9abe3f065554a7fbc59f440df2baba4a6e47ee
2019-10-04 17:36:12 +0000 to 2019-10-15 15:55:35 +0000
- Fix typo in git index initialization error path (rust-lang/cargo#7512)
- Reject feature flags in a virtual workspace. (rust-lang/cargo#7507)
- Rename `overrides` to `package` in profiles. (rust-lang/cargo#7504)
- Allow publishing with dev-dependencies without a version. (rust-lang/cargo#7333)
- Stabilize cache-messages (rust-lang/cargo#7450)
- don't lock the package cache when cleaning target dir. (rust-lang/cargo#7502)
- Document rustc wrapper (rust-lang/cargo#7499)
- Migrate towards exclusively using serde for `Config` (rust-lang/cargo#7456)
- Re-enable some MSVC tests. (rust-lang/cargo#7492)
- when -Z unstable-options not specified, don't validate --profile (rust-lang/cargo#7489)
- Improve error message for cyclic dependencies (rust-lang/cargo#7470)
- Some minor clippy fixes. (rust-lang/cargo#7484)

## book

7 commits in 04806c80be0f54b1290287e3f85e84bdfc0b6ec7..9bb8b161963fcebc9d9ccd732ba26f42108016d5
2019-10-01 20:20:22 -0400 to 2019-10-14 18:42:55 -0500
- Make a portion of text less ambiguous (rust-lang/book#2092)
- fix heading level (rust-lang/book#2117)
- Add missing "of" before `"duck typing"`. (rust-lang/book#1951)
- ch18-03: no need to debug print destructured int (rust-lang/book#1991)
- Subtle fix to introduce ? on Option in Chapter 9.2 (rust-lang/book#2047)
- make wording clearer (rust-lang/book#1976)
- Update the version of rand we use

## rust-by-example

5 commits in a6288e7407a6c4c19ea29de6d43f40c803883f21..0b111eaae36cc4b4997684be853882a59e2c7ca7
2019-10-01 10:09:14 -0300 to 2019-10-14 18:34:25 -0300
- Some fix to three files (rust-lang/rust-by-example#1280)
- Add reference to Generics (rust-lang/rust-by-example#1281)
- Confusing and long sentence (rust-lang/rust-by-example#1282)
- Explicit mention of slice range meaning (rust-lang/rust-by-example#1277)
- Updated aliasing for nll (rust-lang/rust-by-example#1276)
tmandry added a commit to tmandry/rust that referenced this pull request Oct 16, 2019
…chton

Update cargo, cc, books

Update `cc` to include new parallel building support.

## nomicon

3 commits in 4374786f0b4bf0606b35d5c30a9681f342e5707b..5004ad30d69f93553ceef74439fea2159d1f769e
2019-09-17 18:33:21 +0200 to 2019-10-12 19:52:40 +0200
- further clarify C11 and C/C++11 terminology (rust-lang/nomicon#169)
- atomics: C11 -> C++20 (rust-lang/nomicon#168)
- use sound/unsound terminology

## cargo

12 commits in a429e8cc4614a46a86322a0777a477e2baa83f1c..3a9abe3f065554a7fbc59f440df2baba4a6e47ee
2019-10-04 17:36:12 +0000 to 2019-10-15 15:55:35 +0000
- Fix typo in git index initialization error path (rust-lang/cargo#7512)
- Reject feature flags in a virtual workspace. (rust-lang/cargo#7507)
- Rename `overrides` to `package` in profiles. (rust-lang/cargo#7504)
- Allow publishing with dev-dependencies without a version. (rust-lang/cargo#7333)
- Stabilize cache-messages (rust-lang/cargo#7450)
- don't lock the package cache when cleaning target dir. (rust-lang/cargo#7502)
- Document rustc wrapper (rust-lang/cargo#7499)
- Migrate towards exclusively using serde for `Config` (rust-lang/cargo#7456)
- Re-enable some MSVC tests. (rust-lang/cargo#7492)
- when -Z unstable-options not specified, don't validate --profile (rust-lang/cargo#7489)
- Improve error message for cyclic dependencies (rust-lang/cargo#7470)
- Some minor clippy fixes. (rust-lang/cargo#7484)

## book

7 commits in 04806c80be0f54b1290287e3f85e84bdfc0b6ec7..9bb8b161963fcebc9d9ccd732ba26f42108016d5
2019-10-01 20:20:22 -0400 to 2019-10-14 18:42:55 -0500
- Make a portion of text less ambiguous (rust-lang/book#2092)
- fix heading level (rust-lang/book#2117)
- Add missing "of" before `"duck typing"`. (rust-lang/book#1951)
- ch18-03: no need to debug print destructured int (rust-lang/book#1991)
- Subtle fix to introduce ? on Option in Chapter 9.2 (rust-lang/book#2047)
- make wording clearer (rust-lang/book#1976)
- Update the version of rand we use

## rust-by-example

5 commits in a6288e7407a6c4c19ea29de6d43f40c803883f21..0b111eaae36cc4b4997684be853882a59e2c7ca7
2019-10-01 10:09:14 -0300 to 2019-10-14 18:34:25 -0300
- Some fix to three files (rust-lang/rust-by-example#1280)
- Add reference to Generics (rust-lang/rust-by-example#1281)
- Confusing and long sentence (rust-lang/rust-by-example#1282)
- Explicit mention of slice range meaning (rust-lang/rust-by-example#1277)
- Updated aliasing for nll (rust-lang/rust-by-example#1276)
bors added a commit to rust-lang/rust that referenced this pull request Oct 16, 2019
Update cargo, cc, books

Update `cc` to include new parallel building support.

## nomicon

3 commits in 4374786f0b4bf0606b35d5c30a9681f342e5707b..5004ad30d69f93553ceef74439fea2159d1f769e
2019-09-17 18:33:21 +0200 to 2019-10-12 19:52:40 +0200
- further clarify C11 and C/C++11 terminology (rust-lang/nomicon#169)
- atomics: C11 -> C++20 (rust-lang/nomicon#168)
- use sound/unsound terminology

## cargo

12 commits in a429e8cc4614a46a86322a0777a477e2baa83f1c..3a9abe3f065554a7fbc59f440df2baba4a6e47ee
2019-10-04 17:36:12 +0000 to 2019-10-15 15:55:35 +0000
- Fix typo in git index initialization error path (rust-lang/cargo#7512)
- Reject feature flags in a virtual workspace. (rust-lang/cargo#7507)
- Rename `overrides` to `package` in profiles. (rust-lang/cargo#7504)
- Allow publishing with dev-dependencies without a version. (rust-lang/cargo#7333)
- Stabilize cache-messages (rust-lang/cargo#7450)
- don't lock the package cache when cleaning target dir. (rust-lang/cargo#7502)
- Document rustc wrapper (rust-lang/cargo#7499)
- Migrate towards exclusively using serde for `Config` (rust-lang/cargo#7456)
- Re-enable some MSVC tests. (rust-lang/cargo#7492)
- when -Z unstable-options not specified, don't validate --profile (rust-lang/cargo#7489)
- Improve error message for cyclic dependencies (rust-lang/cargo#7470)
- Some minor clippy fixes. (rust-lang/cargo#7484)

## book

7 commits in 04806c80be0f54b1290287e3f85e84bdfc0b6ec7..9bb8b161963fcebc9d9ccd732ba26f42108016d5
2019-10-01 20:20:22 -0400 to 2019-10-14 18:42:55 -0500
- Make a portion of text less ambiguous (rust-lang/book#2092)
- fix heading level (rust-lang/book#2117)
- Add missing "of" before `"duck typing"`. (rust-lang/book#1951)
- ch18-03: no need to debug print destructured int (rust-lang/book#1991)
- Subtle fix to introduce ? on Option in Chapter 9.2 (rust-lang/book#2047)
- make wording clearer (rust-lang/book#1976)
- Update the version of rand we use

## rust-by-example

5 commits in a6288e7407a6c4c19ea29de6d43f40c803883f21..0b111eaae36cc4b4997684be853882a59e2c7ca7
2019-10-01 10:09:14 -0300 to 2019-10-14 18:34:25 -0300
- Some fix to three files (rust-lang/rust-by-example#1280)
- Add reference to Generics (rust-lang/rust-by-example#1281)
- Confusing and long sentence (rust-lang/rust-by-example#1282)
- Explicit mention of slice range meaning (rust-lang/rust-by-example#1277)
- Updated aliasing for nll (rust-lang/rust-by-example#1276)
bors added a commit to rust-lang/rust that referenced this pull request Oct 16, 2019
Update cargo, cc, books

Update `cc` to include new parallel building support.

## nomicon

3 commits in 4374786f0b4bf0606b35d5c30a9681f342e5707b..5004ad30d69f93553ceef74439fea2159d1f769e
2019-09-17 18:33:21 +0200 to 2019-10-12 19:52:40 +0200
- further clarify C11 and C/C++11 terminology (rust-lang/nomicon#169)
- atomics: C11 -> C++20 (rust-lang/nomicon#168)
- use sound/unsound terminology

## cargo

12 commits in a429e8cc4614a46a86322a0777a477e2baa83f1c..3a9abe3f065554a7fbc59f440df2baba4a6e47ee
2019-10-04 17:36:12 +0000 to 2019-10-15 15:55:35 +0000
- Fix typo in git index initialization error path (rust-lang/cargo#7512)
- Reject feature flags in a virtual workspace. (rust-lang/cargo#7507)
- Rename `overrides` to `package` in profiles. (rust-lang/cargo#7504)
- Allow publishing with dev-dependencies without a version. (rust-lang/cargo#7333)
- Stabilize cache-messages (rust-lang/cargo#7450)
- don't lock the package cache when cleaning target dir. (rust-lang/cargo#7502)
- Document rustc wrapper (rust-lang/cargo#7499)
- Migrate towards exclusively using serde for `Config` (rust-lang/cargo#7456)
- Re-enable some MSVC tests. (rust-lang/cargo#7492)
- when -Z unstable-options not specified, don't validate --profile (rust-lang/cargo#7489)
- Improve error message for cyclic dependencies (rust-lang/cargo#7470)
- Some minor clippy fixes. (rust-lang/cargo#7484)

## book

7 commits in 04806c80be0f54b1290287e3f85e84bdfc0b6ec7..9bb8b161963fcebc9d9ccd732ba26f42108016d5
2019-10-01 20:20:22 -0400 to 2019-10-14 18:42:55 -0500
- Make a portion of text less ambiguous (rust-lang/book#2092)
- fix heading level (rust-lang/book#2117)
- Add missing "of" before `"duck typing"`. (rust-lang/book#1951)
- ch18-03: no need to debug print destructured int (rust-lang/book#1991)
- Subtle fix to introduce ? on Option in Chapter 9.2 (rust-lang/book#2047)
- make wording clearer (rust-lang/book#1976)
- Update the version of rand we use

## rust-by-example

5 commits in a6288e7407a6c4c19ea29de6d43f40c803883f21..0b111eaae36cc4b4997684be853882a59e2c7ca7
2019-10-01 10:09:14 -0300 to 2019-10-14 18:34:25 -0300
- Some fix to three files (rust-lang/rust-by-example#1280)
- Add reference to Generics (rust-lang/rust-by-example#1281)
- Confusing and long sentence (rust-lang/rust-by-example#1282)
- Explicit mention of slice range meaning (rust-lang/rust-by-example#1277)
- Updated aliasing for nll (rust-lang/rust-by-example#1276)
bors added a commit to rust-lang/rust that referenced this pull request Oct 16, 2019
Update cargo, books

## nomicon

3 commits in 4374786f0b4bf0606b35d5c30a9681f342e5707b..5004ad30d69f93553ceef74439fea2159d1f769e
2019-09-17 18:33:21 +0200 to 2019-10-12 19:52:40 +0200
- further clarify C11 and C/C++11 terminology (rust-lang/nomicon#169)
- atomics: C11 -> C++20 (rust-lang/nomicon#168)
- use sound/unsound terminology

## cargo

12 commits in a429e8cc4614a46a86322a0777a477e2baa83f1c..3a9abe3f065554a7fbc59f440df2baba4a6e47ee
2019-10-04 17:36:12 +0000 to 2019-10-15 15:55:35 +0000
- Fix typo in git index initialization error path (rust-lang/cargo#7512)
- Reject feature flags in a virtual workspace. (rust-lang/cargo#7507)
- Rename `overrides` to `package` in profiles. (rust-lang/cargo#7504)
- Allow publishing with dev-dependencies without a version. (rust-lang/cargo#7333)
- Stabilize cache-messages (rust-lang/cargo#7450)
- don't lock the package cache when cleaning target dir. (rust-lang/cargo#7502)
- Document rustc wrapper (rust-lang/cargo#7499)
- Migrate towards exclusively using serde for `Config` (rust-lang/cargo#7456)
- Re-enable some MSVC tests. (rust-lang/cargo#7492)
- when -Z unstable-options not specified, don't validate --profile (rust-lang/cargo#7489)
- Improve error message for cyclic dependencies (rust-lang/cargo#7470)
- Some minor clippy fixes. (rust-lang/cargo#7484)

## book

7 commits in 04806c80be0f54b1290287e3f85e84bdfc0b6ec7..9bb8b161963fcebc9d9ccd732ba26f42108016d5
2019-10-01 20:20:22 -0400 to 2019-10-14 18:42:55 -0500
- Make a portion of text less ambiguous (rust-lang/book#2092)
- fix heading level (rust-lang/book#2117)
- Add missing "of" before `"duck typing"`. (rust-lang/book#1951)
- ch18-03: no need to debug print destructured int (rust-lang/book#1991)
- Subtle fix to introduce ? on Option in Chapter 9.2 (rust-lang/book#2047)
- make wording clearer (rust-lang/book#1976)
- Update the version of rand we use

## rust-by-example

5 commits in a6288e7407a6c4c19ea29de6d43f40c803883f21..0b111eaae36cc4b4997684be853882a59e2c7ca7
2019-10-01 10:09:14 -0300 to 2019-10-14 18:34:25 -0300
- Some fix to three files (rust-lang/rust-by-example#1280)
- Add reference to Generics (rust-lang/rust-by-example#1281)
- Confusing and long sentence (rust-lang/rust-by-example#1282)
- Explicit mention of slice range meaning (rust-lang/rust-by-example#1277)
- Updated aliasing for nll (rust-lang/rust-by-example#1276)
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Jan 6, 2020
Version 1.40.0 (2019-12-19)
===========================

Language
--------
- [You can now use tuple `struct`s and tuple `enum` variant's constructors in
  `const` contexts.][65188] e.g.

  ```rust
  pub struct Point(i32, i32);

  const ORIGIN: Point = {
      let constructor = Point;

      constructor(0, 0)
  };
  ```

- [You can now mark `struct`s, `enum`s, and `enum` variants with the `#[non_exhaustive]` attribute to
  indicate that there may be variants or fields added in the future.][64639]
  For example this requires adding a wild-card branch (`_ => {}`) to any match
  statements on a non-exhaustive `enum`. [(RFC 2008)]
- [You can now use function-like procedural macros in `extern` blocks and in
  type positions.][63931] e.g. `type Generated = macro!();`
- [Function-like and attribute procedural macros can now emit
  `macro_rules!` items, so you can now have your macros generate macros.][64035]
- [The `meta` pattern matcher in `macro_rules!` now correctly matches the modern
  attribute syntax.][63674] For example `(#[$m:meta])` now matches `#[attr]`,
  `#[attr{tokens}]`, `#[attr[tokens]]`, and `#[attr(tokens)]`.

Compiler
--------
- [Added tier 3 support\* for the
  `thumbv7neon-unknown-linux-musleabihf` target.][66103]
- [Added tier 3 support for the
  `aarch64-unknown-none-softfloat` target.][64589]
- [Added tier 3 support for the `mips64-unknown-linux-muslabi64`, and
  `mips64el-unknown-linux-muslabi64` targets.][65843]

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

Libraries
---------
- [The `is_power_of_two` method on unsigned numeric types is now a `const` function.][65092]

Stabilized APIs
---------------
- [`BTreeMap::get_key_value`]
- [`HashMap::get_key_value`]
- [`Option::as_deref_mut`]
- [`Option::as_deref`]
- [`Option::flatten`]
- [`UdpSocket::peer_addr`]
- [`f32::to_be_bytes`]
- [`f32::to_le_bytes`]
- [`f32::to_ne_bytes`]
- [`f64::to_be_bytes`]
- [`f64::to_le_bytes`]
- [`f64::to_ne_bytes`]
- [`f32::from_be_bytes`]
- [`f32::from_le_bytes`]
- [`f32::from_ne_bytes`]
- [`f64::from_be_bytes`]
- [`f64::from_le_bytes`]
- [`f64::from_ne_bytes`]
- [`mem::take`]
- [`slice::repeat`]
- [`todo!`]

Cargo
-----
- [Cargo will now always display warnings, rather than only on
  fresh builds.][cargo/7450]
- [Feature flags (except `--all-features`) passed to a virtual workspace will
  now produce an error.][cargo/7507] Previously these flags were ignored.
- [You can now publish `dev-dependencies` without including
  a `version`.][cargo/7333]

Misc
----
- [You can now specify the `#[cfg(doctest)]` attribute to include an item only
  when running documentation tests with `rustdoc`.][63803]

Compatibility Notes
-------------------
- [As previously announced, any previous NLL warnings in the 2015 edition are
  now hard errors.][64221]
- [The `include!` macro will now warn if it failed to include the
  entire file.][64284] The `include!` macro unintentionally only includes the
  first _expression_ in a file, and this can be unintuitive. This will become
  either a hard error in a future release, or the behavior may be fixed to include all expressions as expected.
- [Using `#[inline]` on function prototypes and consts now emits a warning under
  `unused_attribute` lint.][65294] Using `#[inline]` anywhere else inside traits
  or `extern` blocks now correctly emits a hard error.

[65294]: rust-lang/rust#65294
[66103]: rust-lang/rust#66103
[65843]: rust-lang/rust#65843
[65188]: rust-lang/rust#65188
[65092]: rust-lang/rust#65092
[64589]: rust-lang/rust#64589
[64639]: rust-lang/rust#64639
[64221]: rust-lang/rust#64221
[64284]: rust-lang/rust#64284
[63931]: rust-lang/rust#63931
[64035]: rust-lang/rust#64035
[63674]: rust-lang/rust#63674
[63803]: rust-lang/rust#63803
[cargo/7450]: rust-lang/cargo#7450
[cargo/7507]: rust-lang/cargo#7507
[cargo/7525]: rust-lang/cargo#7525
[cargo/7333]: rust-lang/cargo#7333
[(rfc 2008)]: https://rust-lang.github.io/rfcs/2008-non-exhaustive.html
[`f32::to_be_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_be_bytes
[`f32::to_le_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_le_bytes
[`f32::to_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_ne_bytes
[`f64::to_be_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_be_bytes
[`f64::to_le_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_le_bytes
[`f64::to_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_ne_bytes
[`f32::from_be_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_be_bytes
[`f32::from_le_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_le_bytes
[`f32::from_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_ne_bytes
[`f64::from_be_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_be_bytes
[`f64::from_le_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_le_bytes
[`f64::from_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_ne_bytes
[`option::flatten`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.flatten
[`option::as_deref`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref
[`option::as_deref_mut`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref_mut
[`hashmap::get_key_value`]: https://doc.rust-lang.org/std/collections/struct.HashMap.html#method.get_key_value
[`btreemap::get_key_value`]: https://doc.rust-lang.org/std/collections/struct.BTreeMap.html#method.get_key_value
[`slice::repeat`]: https://doc.rust-lang.org/std/primitive.slice.html#method.repeat
[`mem::take`]: https://doc.rust-lang.org/std/mem/fn.take.html
[`udpsocket::peer_addr`]: https://doc.rust-lang.org/std/net/struct.UdpSocket.html#method.peer_addr
[`todo!`]: https://doc.rust-lang.org/std/macro.todo.html
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Jan 14, 2020
Version 1.40.0 (2019-12-19)
===========================

Language
--------
- [You can now use tuple `struct`s and tuple `enum` variant's constructors in
  `const` contexts.][65188] e.g.

  ```rust
  pub struct Point(i32, i32);

  const ORIGIN: Point = {
      let constructor = Point;

      constructor(0, 0)
  };
  ```

- [You can now mark `struct`s, `enum`s, and `enum` variants with the `#[non_exhaustive]` attribute to
  indicate that there may be variants or fields added in the future.][64639]
  For example this requires adding a wild-card branch (`_ => {}`) to any match
  statements on a non-exhaustive `enum`. [(RFC 2008)]
- [You can now use function-like procedural macros in `extern` blocks and in
  type positions.][63931] e.g. `type Generated = macro!();`
- [Function-like and attribute procedural macros can now emit
  `macro_rules!` items, so you can now have your macros generate macros.][64035]
- [The `meta` pattern matcher in `macro_rules!` now correctly matches the modern
  attribute syntax.][63674] For example `(#[$m:meta])` now matches `#[attr]`,
  `#[attr{tokens}]`, `#[attr[tokens]]`, and `#[attr(tokens)]`.

Compiler
--------
- [Added tier 3 support\* for the
  `thumbv7neon-unknown-linux-musleabihf` target.][66103]
- [Added tier 3 support for the
  `aarch64-unknown-none-softfloat` target.][64589]
- [Added tier 3 support for the `mips64-unknown-linux-muslabi64`, and
  `mips64el-unknown-linux-muslabi64` targets.][65843]

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

Libraries
---------
- [The `is_power_of_two` method on unsigned numeric types is now a `const` function.][65092]

Stabilized APIs
---------------
- [`BTreeMap::get_key_value`]
- [`HashMap::get_key_value`]
- [`Option::as_deref_mut`]
- [`Option::as_deref`]
- [`Option::flatten`]
- [`UdpSocket::peer_addr`]
- [`f32::to_be_bytes`]
- [`f32::to_le_bytes`]
- [`f32::to_ne_bytes`]
- [`f64::to_be_bytes`]
- [`f64::to_le_bytes`]
- [`f64::to_ne_bytes`]
- [`f32::from_be_bytes`]
- [`f32::from_le_bytes`]
- [`f32::from_ne_bytes`]
- [`f64::from_be_bytes`]
- [`f64::from_le_bytes`]
- [`f64::from_ne_bytes`]
- [`mem::take`]
- [`slice::repeat`]
- [`todo!`]

Cargo
-----
- [Cargo will now always display warnings, rather than only on
  fresh builds.][cargo/7450]
- [Feature flags (except `--all-features`) passed to a virtual workspace will
  now produce an error.][cargo/7507] Previously these flags were ignored.
- [You can now publish `dev-dependencies` without including
  a `version`.][cargo/7333]

Misc
----
- [You can now specify the `#[cfg(doctest)]` attribute to include an item only
  when running documentation tests with `rustdoc`.][63803]

Compatibility Notes
-------------------
- [As previously announced, any previous NLL warnings in the 2015 edition are
  now hard errors.][64221]
- [The `include!` macro will now warn if it failed to include the
  entire file.][64284] The `include!` macro unintentionally only includes the
  first _expression_ in a file, and this can be unintuitive. This will become
  either a hard error in a future release, or the behavior may be fixed to include all expressions as expected.
- [Using `#[inline]` on function prototypes and consts now emits a warning under
  `unused_attribute` lint.][65294] Using `#[inline]` anywhere else inside traits
  or `extern` blocks now correctly emits a hard error.

[65294]: rust-lang/rust#65294
[66103]: rust-lang/rust#66103
[65843]: rust-lang/rust#65843
[65188]: rust-lang/rust#65188
[65092]: rust-lang/rust#65092
[64589]: rust-lang/rust#64589
[64639]: rust-lang/rust#64639
[64221]: rust-lang/rust#64221
[64284]: rust-lang/rust#64284
[63931]: rust-lang/rust#63931
[64035]: rust-lang/rust#64035
[63674]: rust-lang/rust#63674
[63803]: rust-lang/rust#63803
[cargo/7450]: rust-lang/cargo#7450
[cargo/7507]: rust-lang/cargo#7507
[cargo/7525]: rust-lang/cargo#7525
[cargo/7333]: rust-lang/cargo#7333
[(rfc 2008)]: https://rust-lang.github.io/rfcs/2008-non-exhaustive.html
[`f32::to_be_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_be_bytes
[`f32::to_le_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_le_bytes
[`f32::to_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.to_ne_bytes
[`f64::to_be_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_be_bytes
[`f64::to_le_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_le_bytes
[`f64::to_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.to_ne_bytes
[`f32::from_be_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_be_bytes
[`f32::from_le_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_le_bytes
[`f32::from_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f32.html#method.from_ne_bytes
[`f64::from_be_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_be_bytes
[`f64::from_le_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_le_bytes
[`f64::from_ne_bytes`]: https://doc.rust-lang.org/std/primitive.f64.html#method.from_ne_bytes
[`option::flatten`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.flatten
[`option::as_deref`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref
[`option::as_deref_mut`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.as_deref_mut
[`hashmap::get_key_value`]: https://doc.rust-lang.org/std/collections/struct.HashMap.html#method.get_key_value
[`btreemap::get_key_value`]: https://doc.rust-lang.org/std/collections/struct.BTreeMap.html#method.get_key_value
[`slice::repeat`]: https://doc.rust-lang.org/std/primitive.slice.html#method.repeat
[`mem::take`]: https://doc.rust-lang.org/std/mem/fn.take.html
[`udpsocket::peer_addr`]: https://doc.rust-lang.org/std/net/struct.UdpSocket.html#method.peer_addr
[`todo!`]: https://doc.rust-lang.org/std/macro.todo.html
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