Add Pin::{into_inner,into_inner_unchecked} #60165

Nemo157 · 2019-04-22T11:49:08Z

These functions are useful for unsafe code that needs to temporarily pull smart pointers out of the Pin, e.g. the change that inspired them is taking a Pin<Box<dyn Future>>, turning it into a *mut dyn Future via Box::into_raw(unsafe { Pin::into_inner_unchecked(pin) }) then later dropping this via drop(Pin::from(Box::from_raw(ptr))). This can be accomplished today via { let ptr = unsafe { Pin::get_unchecked_mut(pin.as_mut()) } as *mut dyn Future; mem::forget(pin); ptr }, but this is far more complicated and loses out on the symmetry of using Box::into_raw and Box::from_raw.

I'll extend the documentation on what guarantees into_inner_unchecked needs to uphold once I get some feedback on whether this API is wanted or not.

r? @withoutboats

rust-highfive · 2019-04-22T12:06:32Z

The job x86_64-gnu-llvm-6.0 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:0ff31038:start=1555933812837813930,finish=1555933898149287321,duration=85311473391
$ 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
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
$ export AWS_ACCESS_KEY_ID=AKIA46X5W6CZEJZ6XT55
---

[00:03:28] travis_fold:start:tidy
travis_time:start:tidy
tidy check
[00:03:28] tidy error: /checkout/src/libcore/pin.rs:467: TODO is deprecated; use FIXME
[00:03:30] some tidy checks failed
[00:03:30] 
[00:03:30] 
[00:03:30] 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"
[00:03:30] 
[00:03:30] 
[00:03:30] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
[00:03:30] Build completed unsuccessfully in 0:00:45
[00:03:30] Build completed unsuccessfully in 0:00:45
[00:03:30] make: *** [tidy] Error 1
[00:03:30] Makefile:67: recipe for target 'tidy' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:02ff2c78
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Mon Apr 22 11:55:17 UTC 2019
---
travis_time:end:064c3d02:start=1555934118297159773,finish=1555934118302074393,duration=4914620
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travis_time:start:2d21366c
$ 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
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travis_time:start:0ad175ae
travis_time:start:0ad175ae
$ 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
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travis_time:start:00029930
$ 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)

cramertj · 2019-04-22T21:41:28Z

src/libcore/pin.rs

+    /// [`Unpin`]: ../../std/marker/trait.Unpin.html
+    #[unstable(feature = "pin_into_inner", issue = "0")]
+    #[inline(always)]
+    pub fn into_inner(pin: Pin<P>) -> P {


I'd expected we'd call this method unpin, though maybe that's too clever.

Either seems fine to me, let me know if I should change it.

withoutboats · 2019-04-23T05:04:00Z

These seem like a good idea to add; no opinion about the name.

Nemo157 · 2019-04-24T19:28:48Z

Updated the docs to be similar detail to get{,_unchecked}_mut and added a tracking issue. Once the name question is resolved this is ready.

cramertj · 2019-04-24T19:34:11Z

Maybe someone from @rust-lang/libs has an opinion on the name (into_inner vs. unpin)? If not, this works for me.

alexcrichton · 2019-04-25T17:06:48Z

Since these are unstable I think it's ok to not block on a name and can probably land at any time.

I don't really have much experience personally with pin so a naive take on this is a preference of into_inner since it's an established convention. Again though that's a naive take and we can change our minds at any time while it's unstable!

cramertj · 2019-04-25T17:13:49Z

@bors r+

bors · 2019-04-25T17:13:50Z

📌 Commit a0e0849 has been approved by cramertj

bors · 2019-04-25T17:18:55Z

⌛ Testing commit a0e0849 with merge 9027744c88135cf02ce637f129ec93aafa68e2ca...

bors · 2019-04-25T17:26:16Z

💔 Test failed - checks-travis

rust-highfive · 2019-04-25T17:26:17Z

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.

[00:04:24] sha256:d53c5e2d2845469b98e0a20fb01039c47f8791676fbac22778f4e4cafb2b5bce
[00:04:24] Attempting with retry: docker build --rm -t rust-ci -f /home/travis/build/rust-lang/rust/src/ci/docker/dist-x86_64-linux/Dockerfile /home/travis/build/rust-lang/rust/src/ci/docker
[00:04:24] Sending build context to Docker daemon  520.7kB
[00:04:24] Step 1/41 : FROM centos:5
[00:04:25] Get https://registry-1.docker.io/v2/library/centos/manifests/5: received unexpected HTTP status: 503 Service Unavailable
[00:04:26] Sending build context to Docker daemon  520.7kB
[00:04:26] Step 1/41 : FROM centos:5
[00:04:26] Step 1/41 : FROM centos:5
[00:04:26] Get https://registry-1.docker.io/v2/library/centos/manifests/5: received unexpected HTTP status: 503 Service Unavailable
[00:04:28] Sending build context to Docker daemon  520.7kB
[00:04:28] Step 1/41 : FROM centos:5
[00:04:28] Step 1/41 : FROM centos:5
[00:04:28] Get https://registry-1.docker.io/v2/library/centos/manifests/5: received unexpected HTTP status: 503 Service Unavailable
[00:04:32] Sending build context to Docker daemon  520.7kB
[00:04:32] Step 1/41 : FROM centos:5
[00:04:32] Step 1/41 : FROM centos:5
[00:04:32] Get https://registry-1.docker.io/v2/library/centos/manifests/5: received unexpected HTTP status: 503 Service Unavailable
[00:04:36] Sending build context to Docker daemon  520.7kB
[00:04:36] Step 1/41 : FROM centos:5
[00:04:36] Step 1/41 : FROM centos:5
[00:04:36] Get https://registry-1.docker.io/v2/library/centos/manifests/5: received unexpected HTTP status: 503 Service Unavailable
travis_time:end:116bbe00:start=1556212813284715939,finish=1556213090119882229,duration=276835166290
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 1.
travis_time:start:09596a39
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
---
travis_time:end:00dc330e:start=1556213090932415737,finish=1556213090939344740,duration=6929003
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:0f2f29ee
$ 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
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travis_time:start:344028f0
travis_time:start:344028f0
$ 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:07c52d59
$ 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)

Nemo157 · 2019-04-25T17:29:39Z

Looks like Docker Hub was having issues...

cramertj · 2019-04-25T17:56:28Z

@bors retry

@withoutboats

Add Pin::{into_inner,into_inner_unchecked} These functions are useful for unsafe code that needs to temporarily pull smart pointers out of the `Pin`, e.g. [the change that inspired them](Nemo157/futures-rs@b436178#diff-1a4e0ba4d1b539412ca576411ec6c7c2R258) is taking a `Pin<Box<dyn Future>>`, turning it into a `*mut dyn Future` via `Box::into_raw(unsafe { Pin::into_inner_unchecked(pin) })` then later dropping this via `drop(Pin::from(Box::from_raw(ptr)))`. This can be accomplished today via `{ let ptr = unsafe { Pin::get_unchecked_mut(pin.as_mut()) } as *mut dyn Future; mem::forget(pin); ptr }`, but this is far more complicated and loses out on the symmetry of using `Box::into_raw` and `Box::from_raw`. I'll extend the documentation on what guarantees `into_inner_unchecked` needs to uphold once I get some feedback on whether this API is wanted or not. r? @withoutboats

@withoutboats

Add Pin::{into_inner,into_inner_unchecked} These functions are useful for unsafe code that needs to temporarily pull smart pointers out of the `Pin`, e.g. [the change that inspired them](Nemo157/futures-rs@b436178#diff-1a4e0ba4d1b539412ca576411ec6c7c2R258) is taking a `Pin<Box<dyn Future>>`, turning it into a `*mut dyn Future` via `Box::into_raw(unsafe { Pin::into_inner_unchecked(pin) })` then later dropping this via `drop(Pin::from(Box::from_raw(ptr)))`. This can be accomplished today via `{ let ptr = unsafe { Pin::get_unchecked_mut(pin.as_mut()) } as *mut dyn Future; mem::forget(pin); ptr }`, but this is far more complicated and loses out on the symmetry of using `Box::into_raw` and `Box::from_raw`. I'll extend the documentation on what guarantees `into_inner_unchecked` needs to uphold once I get some feedback on whether this API is wanted or not. r? @withoutboats

@withoutboats

Add Pin::{into_inner,into_inner_unchecked} These functions are useful for unsafe code that needs to temporarily pull smart pointers out of the `Pin`, e.g. [the change that inspired them](Nemo157/futures-rs@b436178#diff-1a4e0ba4d1b539412ca576411ec6c7c2R258) is taking a `Pin<Box<dyn Future>>`, turning it into a `*mut dyn Future` via `Box::into_raw(unsafe { Pin::into_inner_unchecked(pin) })` then later dropping this via `drop(Pin::from(Box::from_raw(ptr)))`. This can be accomplished today via `{ let ptr = unsafe { Pin::get_unchecked_mut(pin.as_mut()) } as *mut dyn Future; mem::forget(pin); ptr }`, but this is far more complicated and loses out on the symmetry of using `Box::into_raw` and `Box::from_raw`. I'll extend the documentation on what guarantees `into_inner_unchecked` needs to uphold once I get some feedback on whether this API is wanted or not. r? @withoutboats

@ghost

Rollup of 12 pull requests Successful merges: - #59734 (Prevent failure in case no space left on device in rustdoc) - #59940 (Set cfg(test) when rustdoc is running with --test option) - #60134 (Fix index-page generation) - #60165 (Add Pin::{into_inner,into_inner_unchecked}) - #60183 (Chalkify: Add builtin Copy/Clone) - #60225 (Introduce hir::ExprKind::Use and employ in for loop desugaring.) - #60247 (Implement Debug for Place using Place::iterate) - #60259 (Derive Default instead of new in applicable lint) - #60267 (Add feature-gate for f16c target feature) - #60284 (Do not allow const generics to depend on type parameters) - #60285 (Do not ICE when checking types against foreign fn) - #60289 (Make `-Z allow-features` work for stdlib features) Failed merges: r? @ghost

bors · 2019-04-26T04:42:07Z

⌛ Testing commit a0e0849 with merge 180edc2...

bors · 2019-04-26T04:51:29Z

☔ The latest upstream changes (presumably #60296) made this pull request unmergeable. Please resolve the merge conflicts.

rust-highfive assigned withoutboats Apr 22, 2019

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 22, 2019

cramertj reviewed Apr 22, 2019

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Nemo157 mentioned this pull request Apr 24, 2019

Tracking issue for Pin::{into_inner, into_inner_unchecked} (feature pin_into_inner) #60245

Closed

Add Pin::{into_inner,into_inner_unchecked}

a0e0849

Nemo157 force-pushed the pin-into-inner branch from d4b92cd to a0e0849 Compare April 24, 2019 19:20

Nemo157 mentioned this pull request Apr 24, 2019

Remove StreamObj, caution against using FutureObj rust-lang/futures-rs#1494

Merged

Nemo157 mentioned this pull request Apr 25, 2019

Change FutureObj to use a *mut dyn Future fat pointer rust-lang/futures-rs#1550

Merged

bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Apr 25, 2019

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 25, 2019

bors 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-review Status: Awaiting review from the assignee but also interested parties. labels Apr 25, 2019

Centril mentioned this pull request Apr 25, 2019

Rollup of 10 pull requests #60290

Closed

Centril mentioned this pull request Apr 25, 2019

Rollup of 10 pull requests #60291

Closed

Centril mentioned this pull request Apr 26, 2019

Rollup of 12 pull requests #60296

Merged

bors merged commit a0e0849 into rust-lang:master Apr 26, 2019

bors 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 26, 2019

pnkfelix mentioned this pull request Jun 20, 2019

regression: trait no longer implemented #61563

Closed

Nemo157 deleted the pin-into-inner branch August 27, 2019 10:12

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Add Pin::{into_inner,into_inner_unchecked} #60165

Add Pin::{into_inner,into_inner_unchecked} #60165

Nemo157 commented Apr 22, 2019

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bors commented Apr 26, 2019

Add Pin::{into_inner,into_inner_unchecked} #60165

Add Pin::{into_inner,into_inner_unchecked} #60165

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