Add test for rustdoc ignore test

[Phlosioneer]

This will check for regression on issue #32556

[TimNN]

Your PR failed on Travis. 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.

Resolving deltas: 100% (611993/611993), completed with 4842 local objects.
---
[00:00:44] configure: rust.quiet-tests     := True
---
[00:04:02] tidy error: /checkout/src/test/rustdoc/issue-32556.rs: too many trailing newlines (3)

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.

[GuillaumeGomez]

There shouldn't be a whitespace before ignore.

[GuillaumeGomez]

2016? 😆

[Phlosioneer]

Oops! Dangers of copy-pasting!

[TimNN]

Your PR failed on Travis. 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.

Resolving deltas: 100% (612016/612016), completed with 4840 local objects.
---
[00:00:47] configure: rust.quiet-tests     := True
---
[00:04:50] tidy error: /checkout/src/test/rustdoc/issue-32556.rs:12: unexplained "```ignore" doctest; try one:
[00:04:50]
[00:04:50] * make the test actually pass, by adding necessary imports and declarations, or
[00:04:50] * use "```text", if the code is not Rust code, or
[00:04:50] * use "```compile_fail,Ennnn", if the code is expected to fail at compile time, or
[00:04:50] * use "```should_panic", if the code is expected to fail at run time, or
[00:04:50] * use "```no_run", if the code should type-check but not necessary linkable/runnable, or
[00:04:50] * explain it like "```ignore (cannot-test-this-because-xxxx)", if the annotation cannot be avoided.
[00:04:50]
[00:04:50]
[00:04:51] some tidy checks failed
[00:04:51]
[00:04:51]
[00:04:51] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "--no-vendor" "--quiet"
[00:04:51] expected success, got: exit code: 1
[00:04:51]
[00:04:51]
[00:04:51] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:04:51] Build completed unsuccessfully in 0:02:04
[00:04:51] make: *** [tidy] Error 1
[00:04:51] Makefile:79: recipe for target 'tidy' failed
---
$ cat obj/tmp/sccache.log
---
$ ls -lat $HOME/Library/Logs/DiagnosticReports/
ls: cannot access /home/travis/Library/Logs/DiagnosticReports/: No such file or directory
travis_time:end:22a2a68f:start=1522527429816823904,finish=1522527429823929748,duration=7105844
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:1b9a9fbf
$ 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:1b9a9fbf:start=1522527429830172763,finish=1522527429836782326,duration=6609563
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:0a816479
$ dmesg | grep -i kill
[   11.029853] 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.

[GuillaumeGomez]

Thanks!

@bors: r+ rollup

[bors]

📌 Commit cb30975 has been approved by GuillaumeGomez