r? @aturon

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I wrote that comment wrong :P

Hi @aturon :)

This method should be available in libcore too, so needs to be added to SliceExt, don't you agree?

Note, this does not fix the tracking issue -- the issue is open until the feature is stable.

@bluss alright, I'll take out that thing about "fixes".

Also, yes I do think it should go in SliceExt. I'll implement that tonight.

Thanks @ubsan! In addition to what @bluss mentioned, could you also add a positive test which asserts that the behavior is as expected?

@alexcrichton will do :)

Great! Let's go..

@bors r+ 849c4ce

@bors r-

travis found this one

src/libcollections/lib.rs:35:12: 35:27 error: unused or unknown feature, #[deny(unused_features)] on by default

src/libcollections/lib.rs:35 #![feature(copy_from_slice)]

Ok that's really weird, probably bug #30209

@bluss that's weird, it worked on my end... I specifically added an unstable attribute, and then added a feature, and compiled and it worked.

Edit: and... it doesn't work for me if I take out the feature...

src/libcollections/slice.rs:859:9: 859:46 error: use of unstable library feature 'copy_from_slice' (see issue #31755)
src/libcollections/slice.rs:859         core_slice::SliceExt::copy_from_slice(self, src)

But then the libcollections code changed to just and UFCS trait method call, which is what the bug indicates

stage1 seems to have no such unused feature warning, but stage2 does when compiling libcollections.

When compiling libcollectionstest actually.

I think you'll just need to add this to the top of libcollections:

#![cfg_attr(not(test), feature(...))]

Yeah that seems to be right. That was a bit confusing.

Did you mean to have the libcollectionstest tests replace the run-pass/run-fail tests? I.e. remove the other ones?

@bluss yes. Is that not what our tests should be? I am super confused about our tests :P

having them in just libcollectionstests seems good.

cool :)

Feel free to squash the commits together if you want (to create a cleaner history).

@bluss will do

Can we delete the two files in src/tests/ ? They are redundant now.

r=me without the redundant tests. I'm happy this is finally landing!

@bluss I thought I had deleted those :/

@bluss I feel like kind of a dumb right now :P

@bors: r+ e12b1f9

Thanks @ubsan!

⌛ Testing commit e12b1f9 with merge 0913004...

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-mac-ios-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt