Stabilize str::escape_* methods with new return types…

[SimonSapin]

… that implement Display and Iterator<Item=char>, as proposed in FCP: #27791 (comment)

[rust-highfive]

r? @aidanhs

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[rust-highfive]

The job x86_64-gnu-llvm-6.0 of 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.

travis_time:end:08a94ecf:start=1549103236743417801,finish=1549103308760072175,duration=72016654374
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-6.0
---
travis_time:start:test_debuginfo
Check compiletest suite=debuginfo mode=debuginfo-both (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
[01:10:02] 
[01:10:02] running 119 tests
[01:10:28] .iiiii...i.....i..i...i..i.i..i.ii...i.....i..i....i..........iiii..........i...ii...i.......ii.i.i. 100/119
[01:10:32] i......iii.i.....ii
[01:10:32] 
[01:10:32]  finished in 29.606
[01:10:32] travis_fold:end:test_debuginfo

---
[01:36:08] travis_fold:end:stage0-linkchecker

[01:36:08] travis_time:end:stage0-linkchecker:start=1549109083829891554,finish=1549109085905854123,duration=2075962569

[01:36:15] core/str/struct.EscapeDefault.html:1: broken link - core/str/primitive.str.html
[01:36:15] core/str/index.html:10: broken link - core/str/primitive.str.html
[01:36:15] core/str/index.html:11: broken link - core/str/primitive.str.html
[01:36:15] core/str/index.html:12: broken link - core/str/primitive.str.html
[01:36:15] core/str/struct.EscapeUnicode.html:1: broken link - core/str/primitive.str.html
[01:36:15] core/str/struct.EscapeDebug.html:1: broken link - core/str/primitive.str.html
[01:36:15] thread 'main' panicked at 'found some broken links', src/tools/linkchecker/main.rs:39:9
[01:36:15] 
[01:36:15] 
[01:36:15] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/linkchecker" "/checkout/obj/build/x86_64-unknown-linux-gnu/doc"
[01:36:15] expected success, got: exit code: 101
[01:36:15] expected success, got: exit code: 101
[01:36:15] 
[01:36:15] 
[01:36:15] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:36:15] Build completed unsuccessfully in 0:37:59
[01:36:15] Makefile:48: recipe for target 'check' failed
[01:36:15] make: *** [check] Error 1
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:10b88872
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Sat Feb  2 12:04:54 UTC 2019
---
travis_time:end:08d76c70:start=1549109095660083263,finish=1549109095666728655,duration=6645392
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:10326bc0
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:06d5f728
travis_time:start:06d5f728
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:0d5829d0
$ dmesg | grep -i kill

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)

[bors]

☔ The latest upstream changes (presumably #58081) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #58189) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #58254) made this pull request unmergeable. Please resolve the merge conflicts.

[bors]

☔ The latest upstream changes (presumably #58389) made this pull request unmergeable. Please resolve the merge conflicts.

[SimonSapin]

r? @alexcrichton

[alexcrichton]

@bors: r+

[bors]

📌 Commit eb158f9 has been approved by alexcrichton

[bors]

⌛ Testing commit eb158f9 with merge 0f949c2...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: alexcrichton
Pushing 0f949c2 to master...

[rust-highfive]

📣 Toolstate changed by #58051!

Tested on commit 0f949c2.
Direct link to PR: #58051

💔 rustfmt on windows: test-pass → build-fail (cc @nrc, @rust-lang/infra).
💔 rustfmt on linux: test-pass → build-fail (cc @nrc, @rust-lang/infra).