Add str::split_ascii_whitespace.

[clarfonthey]

As mentioned in #48656.

While str::split_whitespace now works in libcore, it still makes sense to offer this method, considering how it is still more performant in cases where only ASCII is necessary.

[rust-highfive]

r? @bluss

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[rust-highfive]

Your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:00:47] configure: rust.quiet-tests     := True
---
[00:03:09] error[E0277]: the trait bound `for<'r> str::IsAsciiWhitespace: ops::function::FnMut<(&'r u8,)>` is not satisfied
[00:03:09]     --> libcore/str/mod.rs:2635:5
[00:03:09]      |
[00:03:09] 2635 |     inner: Map<Filter<SliceSplit<'a, u8, IsAsciiWhitespace>, IsNotEmpty>, BytesToStr>,
[00:03:09]      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'r> ops::function::FnMut<(&'r u8,)>` is not implemented for `str::IsAsciiWhitespace`
[00:03:09]      |
[00:03:09] note: required by `slice::Split`
[00:03:09]     --> libcore/slice/mod.rs:1655:1
[00:03:09]      |
[00:03:09] 1655 | pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
---
[00:03:12] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "--release" "--locked" "--color" "always" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "--message-format" "json"
[00:03:12] expected success, got: exit code: 101
[00:03:12] thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1085:9
[00:03:12] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:03:12] travis_fold:end:stage0-std
[00:03:12] travis_time:end:stage0-std:start=1523825587941191947,finish=1523825599238220358,duration=11297028411
[00:03:12] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:03:12] Build completed unsuccessfully in 0:00:12
[00:03:12] Makefile:79: recipe for target 'tidy' failed
[00:03:12] make: *** [tidy] Error 1
---
$ ls -lat $HOME/Library/Logs/DiagnosticReports/
ls: cannot access /home/travis/Library/Logs/DiagnosticReports/: No such file or directory
travis_time:end:0e665b96:start=1523825599726098956,finish=1523825599732533241,duration=6434285
travis_fold:end:after_failure.2
travis_fold:start:after_failure.3
travis_time:start:15481c42
$ find $HOME/Library/Logs/DiagnosticReports -type f -name '*.crash' -not -name '*.stage2-*.crash' -not -name 'com.apple.CoreSimulator.CoreSimulatorService-*.crash' -exec printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" {} \; -exec head -750 {} \; -exec echo travis_fold":"end:crashlog \; || true
find: `/home/travis/Library/Logs/DiagnosticReports': No such file or directory
travis_time:end:15481c42:start=1523825599738037634,finish=1523825599743859096,duration=5821462
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:05d172d8
$ dmesg | grep -i kill
[   10.219692] init: failsafe main process (1096) killed by TERM signal

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[rust-highfive]

Your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

[00:00:48] configure: rust.quiet-tests     := True
---
[00:03:11] error[E0277]: the trait bound `for<'r> str::IsAsciiWhitespace: ops::function::FnMut<(&'r u8,)>` is not satisfied
[00:03:11]     --> libcore/str/mod.rs:2635:5
[00:03:11]      |
[00:03:11] 2635 |     inner: Map<Filter<SliceSplit<'a, u8, IsAsciiWhitespace>, IsNotEmpty>, BytesToStr>,
[00:03:11]      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'r> ops::function::FnMut<(&'r u8,)>` is not implemented for `str::IsAsciiWhitespace`
[00:03:11]      |
[00:03:11] note: required by `slice::Split`
[00:03:11]     --> libcore/slice/mod.rs:1655:1
[00:03:11]      |
[00:03:11] 1655 | pub struct Split<'a, T:'a, P> where P: FnMut(&T) -> bool {
---
[00:03:14] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "--release" "--locked" "--color" "always" "--features" "panic-unwind jemalloc backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "--message-format" "json"
[00:03:14] expected success, got: exit code: 101
[00:03:14] thread 'main' panicked at 'cargo must succeed', bootstrap/compile.rs:1085:9
[00:03:14] note: Run with `RUST_BACKTRACE=1` for a backtrace.
[00:03:14] travis_fold:end:stage0-std
[00:03:14] travis_time:end:stage0-std:start=1523826888830573051,finish=1523826900542284021,duration=11711710970
[00:03:14] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:03:14] Build completed unsuccessfully in 0:00:12
[00:03:14] Makefile:79: recipe for target 'tidy' failed
[00:03:14] make: *** [tidy] Error 1
---
$ ls -lat $HOME/Library/Logs/DiagnosticReports/
ls: cannot access /home/travis/Library/Logs/DiagnosticReports/: No such file or directory
travis_time:end:1e050dde:start=1523826901630436855,finish=1523826901637034378,duration=6597523
travis_fold:end:after_failure.2
travis_fold:start:after_failure.3
travis_time:start:012eeec5
$ find $HOME/Library/Logs/DiagnosticReports -type f -name '*.crash' -not -name '*.stage2-*.crash' -not -name 'com.apple.CoreSimulator.CoreSimulatorService-*.crash' -exec printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" {} \; -exec head -750 {} \; -exec echo travis_fold":"end:crashlog \; || true
find: `/home/travis/Library/Logs/DiagnosticReports': No such file or directory
travis_time:end:012eeec5:start=1523826901642919086,finish=1523826901648654846,duration=5735760
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:1a23cb7b
$ dmesg | grep -i kill
[   10.398374] init: failsafe main process (1092) killed by TERM signal

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[jcarres-mdsol]

Does this need to be standard lib?
If anything it could be split_whitespace_ascii so always shows next to the other whitespace method

[clarfonthey]

@jcarres-mdsol Methods are sorted in the order they're defined, and I'd really rather not have is_ascii_whitespace but split_whitespace_ascii.

[bors]

☔ The latest upstream changes (presumably #49896) made this pull request unmergeable. Please resolve the merge conflicts.

[pietroalbini]

Ping from triage @clarcharr! There are conflicts that needs to be resolved, and the tests are currently failing.

[clarfonthey]

Rebased! Sorry it took so long.

[clarfonthey]

(This is ready for review @bluss)

[TimNN]

Ping from triage, @bluss / @rust-lang/libs, this PR needs your review.

[pietroalbini]

Ping from triage! This PR needs a review, can @bluss or someone else from @rust-lang/libs review this?

[pietroalbini]

Ping from triage! It's more than 20 days since this PR needed a review. Can @bluss or someone else from @rust-lang/libs review this?

[SimonSapin]

This really should be an unsafe fn, but unfortunately that’s not supported by the Fn* traits. It’s not essential though since this is a private type.

Maybe renaming the type to UncheckedBytesToStr and adding a comment that it is unsafe to use? Feel free to submit another PR for this, I’ll r+ this one now so that it doesn’t bitrot again.

[SimonSapin]

@bors r+

[bors]

📌 Commit 0ce3ea2c968a64b382aed9ee26f59c1db158eb2c has been approved by SimonSapin

[bors]

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

1. git checkout split_ascii_whitespace (switch to your branch)
2. git fetch upstream master (retrieve the latest master)
3. git rebase upstream/master -p (rebase on top of it)
4. Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
5. git push self split_ascii_whitespace --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging src/libcore/str/mod.rs
CONFLICT (file/directory): There is a directory with name src/libbacktrace in heads/homu-tmp. Adding src/libbacktrace as src/libbacktrace~HEAD
Auto-merging src/liballoc/str.rs
Auto-merging src/liballoc/lib.rs
Automatic merge failed; fix conflicts and then commit the result.

[pietroalbini]

@clarcharr could you please rebase on top of the latest master, even if you don't see any conflict? Thanks!

[clarfonthey]

Will do!

Also I'll make the change @SimonSapin suggested. IMHO these should really be using impl Fn to have the same effect but not require a separate type, although I'll do that in a separate PR.

[SimonSapin]

Can impl Fn syntax be used inside a struct definition?

[clarfonthey]

@SimonSapin Through some form of abstract type, yes. Although this doesn't appear to be implemented yet so that'll have to happen later.

[clarfonthey]

Also, rebased.

[SimonSapin]

@bors r+

[bors]

📌 Commit b5cee02 has been approved by SimonSapin