[std] Osstr lossy example

[jnqnfe]

No description provided.

[rust-highfive]

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[alexcrichton]

Thanks for the PR! Can this be implemented as an example without making it memory unsafe though? As-is this is susceptible to future breakage because the example itself is exhibiting memory unsafety.

[jnqnfe]

Thanks for the PR! Can this be implemented as an example without making it memory unsafe though? As-is this is susceptible to future breakage because the example itself is exhibiting memory unsafety.

The only options are (as far as I can see)
a) doing it the way I have, via an unchecked String
b) transmuting a byte array, which I'd assume you'd object to more
c) splitting the example to work differently on different platforms, to take advantage of the from-byte-slice unix extension method, which would be a mess

otherwise the OsStr methods in std would need to be extended to provide a cleaner solution

fyi, this and a couple of other similar push requests were a precursor to a further push request to extend OsStr handling in std to allow splitting, as needed by an upcoming v2.0 of my cmd-line arg parsing library (which is currently having to transmute). I started investigating how best to implement that, but never got around to finishing. The best solution for that would likely be to just open up from/to byte array methods, perhaps with method names like to_storage_byes to try to help reinforce the message that OsStr does not store the string in the OS form on some platforms.

[alexcrichton]

Yes to implement this the best way would be via the OS extension traits such as OsStr::from_bytes on Unix.

[XAMPPRocky]

Triage; @jnqnfe Hello, have you been able to get back to this PR?

[jnqnfe]

@Aaronepower @alexcrichton Yes, sorry for the delay, I'm largely working offline with no internet from home.

I've reworked the change as suggested. I also fixed it so that it will actually work correctly on Windows, having corrected a misunderstanding from not examining closely enough what the Windows/WTF-8 to-lossy code was doing.

[alexcrichton]

@bors: r+

Looks good to me, thanks!

[bors]

📌 Commit 0008e0d has been approved by alexcrichton

[bors]

⌛ Testing commit 0008e0d with merge 9d1f8f1c6ed41d9d60ec402a1c345b2838cfe6e6...

[bors]

💔 Test failed - status-travis

[rust-highfive]

The job dist-i686-freebsd 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.

Building stage2 tool cargo (i686-unknown-freebsd)
[01:08:29]  Downloading crates ...
[01:08:49] warning: spurious network error (2 tries remaining): [6] Couldn't resolve host name (Could not resolve host: crates.io)
[01:09:09] warning: spurious network error (1 tries remaining): [6] Couldn't resolve host name (Could not resolve host: crates.io)
[01:09:29] error: failed to download from `https://crates.io/api/v1/crates/openssl-src/111.1.0+1.1.1a/download`
[01:09:29] Caused by:
[01:09:29]   [6] Couldn't resolve host name (Could not resolve host: crates.io)
[01:09:29] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "i686-unknown-freebsd" "-j" "4" "--release" "--locked" "--color" "always" "--manifest-path" "/checkout/src/tools/cargo/Cargo.toml" "--features" "rustc-workspace-hack/all-static" "--message-format" "json"
[01:09:29] expected success, got: exit code: 101
---
travis_time:end:22f3fd00:start=1544685027560141474,finish=1544685027571474577,duration=11333103
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:0ed8d9f4
$ 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:07bdec5d
travis_time:start:07bdec5d
$ 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:0161be90
$ 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)

[kennytm]

@bors retry travis-ci/travis-ci#9696

[bors]

⌛ Testing commit 0008e0d with merge 5900dae...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing 5900dae to master...