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Make UnsafeCell::into_inner safe #47204

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merged 1 commit into from
Jan 28, 2018

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varkor
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@varkor varkor commented Jan 5, 2018

This fixes #35067. It will require a Crater run as discussed in that
issue.

This fixes rust-lang#35067. It will require a Crater run as discussed in that
issue.
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r? @Mark-Simulacrum

(rust_highfive has picked a reviewer for you, use r? to override)

@kennytm kennytm added S-waiting-on-crater Status: Waiting on a crater run to be completed. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-crater Status: Waiting on a crater run to be completed. labels Jan 5, 2018
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r? @BurntSushi

@bors try

cc @aidanhs for crater

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bors commented Jan 5, 2018

⌛ Trying commit 4829d50 with merge 68950fc...

bors added a commit that referenced this pull request Jan 5, 2018
Make UnsafeCell::into_inner safe

This fixes #35067. It will require a Crater run as discussed in that
issue.
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cramertj commented Jan 5, 2018

This shouldn't need a crater anymore since this works now:

let x: unsafe fn(_) -> _ = UnsafeCell::<u32>::into_inner;

I added that conversion way back in #37389.

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bors commented Jan 5, 2018

💔 Test failed - status-travis

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It still technically needs a crater run. There are other ways to expose the type. e.g. you might have a trait implemented only for unsafe fn() and so forth.

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cramertj commented Jan 5, 2018

@nikomatsakis Even then you'd still have to trigger the coercion to unsafe fn() first, wouldn't you? For example:

trait Foo {
    fn bar(&self) {}
}

impl Foo for unsafe fn() {}

unsafe fn baz() {}

fn main() {
    // These do not work:
    baz.bar();
    Foo::bar(&baz);

    // These do:
    let x: unsafe fn() = baz;
    x.bar();
    Foo::bar(&x);
}

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@cramertj ah, hmm, good point. You may be right. =)

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errrrr try failed because of... cargo? I'm going to see if retrying works...

@bors try

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kennytm commented Jan 10, 2018

@bors clean retry try

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bors commented Jan 10, 2018

⌛ Trying commit 4829d50 with merge 15e0ec4...

bors added a commit that referenced this pull request Jan 10, 2018
Make UnsafeCell::into_inner safe

This fixes #35067. It will require a Crater run as discussed in that
issue.
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bors commented Jan 10, 2018

💔 Test failed - status-travis

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kennytm commented Jan 10, 2018

Nope doesn't work. Cargo needs to add #[allow(unused_unsafe)] for their LazyCell.

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This is a breaking change because of the deny(warnings) resulting the compilation failure, though it is minor. We have done this in the past, though (most recently with the ASCII extension traits). @rust-lang/libs: Do we want to do this considering the breaking change aspect?

@Mark-Simulacrum Mark-Simulacrum added the relnotes Marks issues that should be documented in the release notes of the next release. label Jan 10, 2018
@alexcrichton alexcrichton added S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 10, 2018
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@rfcbot fcp merge

Curious to see what the libs team thinks!

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rfcbot commented Jan 10, 2018

Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged teams:

No concerns currently listed.

Once these reviewers reach consensus, this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

@rfcbot rfcbot added the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Jan 10, 2018
@rfcbot rfcbot added the final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. label Jan 23, 2018
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rfcbot commented Jan 23, 2018

🔔 This is now entering its final comment period, as per the review above. 🔔

@rfcbot rfcbot removed the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Jan 23, 2018
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@bors: r+

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bors commented Jan 23, 2018

📌 Commit 4829d50 has been approved by alexcrichton

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bors commented Jan 24, 2018

⌛ Testing commit 4829d50 with merge ea2b106d7305b530c34266858ecbd55bfcae03b3...

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bors commented Jan 24, 2018

💔 Test failed - status-travis

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kennytm commented Jan 24, 2018

Same error as #47204 (comment), please fix cargo first.

(Triage: Blocked by rust-lang/cargo#4972)

@kennytm kennytm added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-team Status: Awaiting decision from the relevant subteam (see the T-<team> label). labels Jan 24, 2018
varkor added a commit to varkor/cargo that referenced this pull request Jan 24, 2018
rust-lang/rust#47204 makes `UnsafeCell::into_inner` safe, which means `LazyCell::into_inner` will no longer need an `unsafe` block. `LazyCell` is a blocker for the change in Rust: this fix should allow the change to take place.
@kennytm kennytm added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 24, 2018
bors added a commit to rust-lang/cargo that referenced this pull request Jan 24, 2018
Allow unused_unsafe in LazyCell in preparation for lib change

rust-lang/rust#47204 makes `UnsafeCell::into_inner` safe, which means `LazyCell::into_inner` will no longer need an `unsafe` block. `LazyCell` is a blocker for the change in Rust: this fix should allow the change to take place.
@kennytm kennytm added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels Jan 28, 2018
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kennytm commented Jan 28, 2018

@bors retry

The cargo on master contained rust-lang/cargo#4972 already.

@kennytm kennytm added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 28, 2018
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bors commented Jan 28, 2018

⌛ Testing commit 4829d50 with merge 21882aa...

bors added a commit that referenced this pull request Jan 28, 2018
Make UnsafeCell::into_inner safe

This fixes #35067. It will require a Crater run as discussed in that
issue.
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bors commented Jan 28, 2018

💔 Test failed - status-appveyor

@alexcrichton alexcrichton merged commit 4829d50 into rust-lang:master Jan 28, 2018
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Er this passed, just a 3 hour timeout, merged manually

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UnsafeCell::into_inner should not be unsafe