Iterator::single

[real-felix]

Hi, I wrote there about an idea I had, and everybody seemed to see this as a good idea. So here is my PR for Iterator::single: this method returns Some(item) if this item is single in the iterator, otherwise it returns None. What do you think of this?

This is my first contribution, so I'm not aware of how it works. For example, I do not know what to put in the issue field of the unstable attribute. I'm waiting for your comments/suggestions!

[rust-highfive]

The job x86_64-gnu-llvm-5.0 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:10b39898:start=1540498386240094100,finish=1540498472821117132,duration=86581023032
$ 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 SCCACHE_BUCKET=rust-lang-ci-sccache2
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[00:04:07] tidy error: /checkout/src/libcore/iter/iterator.rs:611: trailing whitespace
[00:04:08] some tidy checks failed
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[00:04:08] 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"
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[00:04:08] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:04:08] Build completed unsuccessfully in 0:00:44
[00:04:08] Build completed unsuccessfully in 0:00:44
[00:04:08] make: *** [tidy] Error 1
[00:04:08] Makefile:79: recipe for target 'tidy' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
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$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
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$ 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
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$ 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
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$ dmesg | grep -i kill

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[jonas-schievink]

This appears to be a duplicate of #55355

[real-felix]

This appears to be a duplicate of #55355

I proposed an idea, someone said to me that I should submit a PR, so it took me long to tame the compiler build system and to add my implementation; and then someone else did the PR 2 hours before mine. He could have at least notified me that he was doing the job before that. That's no incentive for me to contribute any more.

[jonas-schievink]

Yeah this happens from time to time. It might have been a good idea to explicitly state that you're working on this in the internals thread.

[real-felix]

Yeah this happens from time to time. It might have been a good idea to explicitly state that you're working on this in the internals thread.

I'll do it next time. Thanks for the advice.