Relax some Ord bounds on BinaryHeap<T>

[nox]

Notably, iterators don't require any trait bounds to be iterated.

[rust-highfive]

r? @dtolnay

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[rust-highfive]

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:013df1ec:start=1550057154270271884,finish=1550057155337474030,duration=1067202146
$ 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 IMAGE=x86_64-gnu-llvm-6.0
---
[00:06:39]    Compiling rustc_msan v0.0.0 (/checkout/src/librustc_msan)
[00:06:39]    Compiling rustc_asan v0.0.0 (/checkout/src/librustc_asan)
[00:06:39]    Compiling rustc_tsan v0.0.0 (/checkout/src/librustc_tsan)
[00:07:00]    Compiling rustc-std-workspace-core v1.0.0 (/checkout/src/tools/rustc-std-workspace-core)
[00:07:03] error[E0277]: the trait bound `T: core::cmp::Ord` is not satisfied
[00:07:03]     |
[00:07:03]     |
[00:07:03] 230 | impl<T: fmt::Debug> fmt::Debug for PeekMut<'_, T> {
[00:07:03]     |                     ^^^^^^^^^^ the trait `core::cmp::Ord` is not implemented for `T`
[00:07:03]     |
[00:07:03]     = help: consider adding a `where T: core::cmp::Ord` bound
[00:07:03] note: required by `collections::binary_heap::PeekMut`
[00:07:03]     |
[00:07:03]     |
[00:07:03] 224 | pub struct PeekMut<'a, T: 'a + Ord> {
[00:07:03] 
[00:07:03] 
[00:07:03] error[E0277]: the trait bound `T: core::cmp::Ord` is not satisfied
[00:07:03]     |
[00:07:03]     |
[00:07:03] 248 | impl<T> Deref for PeekMut<'_, T> {
[00:07:03]     |
[00:07:03]     |
[00:07:03] 224 | pub struct PeekMut<'a, T: 'a + Ord> {
[00:07:03] 
[00:07:03] 
[00:07:03] error[E0277]: the trait bound `T: core::cmp::Ord` is not satisfied
[00:07:03]     |
[00:07:03]     |
[00:07:03] 231 | /     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
[00:07:03] 232 | |         f.debug_tuple("PeekMut")
[00:07:03] 233 | |          .field(&self.heap.data[0])
[00:07:03] 234 | |          .finish()
[00:07:03] 235 | |     }
[00:07:03]     | |_____^ the trait `core::cmp::Ord` is not implemented for `T`
[00:07:03]     |
[00:07:03]     = help: consider adding a `where T: core::cmp::Ord` bound
[00:07:03] note: required by `collections::binary_heap::PeekMut`
[00:07:03]     |
[00:07:03]     |
[00:07:03] 224 | pub struct PeekMut<'a, T: 'a + Ord> {
[00:07:03] 
[00:07:03] 
[00:07:03] error[E0277]: the trait bound `T: core::cmp::Ord` is not satisfied
[00:07:03]     |
[00:07:03]     |
[00:07:03] 250 | /     fn deref(&self) -> &T {
[00:07:03] 251 | |         debug_assert!(!self.heap.is_empty());
[00:07:03] 252 | |         // SAFE: PeekMut is only instantiated for non-empty heaps
[00:07:03] 253 | |         unsafe { self.heap.data.get_unchecked(0) }
[00:07:03] 254 | |     }
[00:07:03]     | |_____^ the trait `core::cmp::Ord` is not implemented for `T`
[00:07:03]     |
[00:07:03]     = help: consider adding a `where T: core::cmp::Ord` bound
[00:07:03] note: required by `collections::binary_heap::PeekMut`
[00:07:03]     |
[00:07:03]     |
[00:07:03] 224 | pub struct PeekMut<'a, T: 'a + Ord> {
[00:07:03] 
[00:07:03] 
[00:07:03] error[E0277]: the trait bound `T: core::cmp::Ord` is not satisfied
[00:07:03]     |
[00:07:03] 259 | /     fn deref_mut(&mut self) -> &mut T {
[00:07:03] 259 | /     fn deref_mut(&mut self) -> &mut T {
[00:07:03] 260 | |         debug_assert!(!self.heap.is_empty());
[00:07:03] 261 | |         // SAFE: PeekMut is only instantiated for non-empty heaps
[00:07:03] 262 | |         unsafe { self.heap.data.get_unchecked_mut(0) }
[00:07:03] 263 | |     }
[00:07:03]     | |_____^ the trait `core::cmp::Ord` is not implemented for `T`
[00:07:03]     |
[00:07:03]     = help: consider adding a `where T: core::cmp::Ord` bound
[00:07:03] note: required by `collections::binary_heap::PeekMut`
[00:07:03]     |
[00:07:03]     |
[00:07:03] 224 | pub struct PeekMut<'a, T: 'a + Ord> {
[00:07:03] 
[00:07:03] error: aborting due to 6 previous errors
[00:07:03] 
[00:07:03] For more information about this error, try `rustc --explain E0277`.
[00:07:03] For more information about this error, try `rustc --explain E0277`.
[00:07:03] error: Could not compile `alloc`.
[00:07:03] 
[00:07:03] To learn more, run the command again with --verbose.
[00:07:03] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "-j" "4" "--release" "--locked" "--color" "always" "--features" "panic-unwind backtrace" "--manifest-path" "/checkout/src/libstd/Cargo.toml" "--message-format" "json"
[00:07:03] expected success, got: exit code: 101
[00:07:03] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap build
[00:07:03] Build completed unsuccessfully in 0:00:37
[00:07:04] make: *** [all] Error 1
[00:07:04] Makefile:18: recipe for target 'all' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:0ad1c6a7
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Wed Feb 13 11:33:09 UTC 2019
---
travis_time:end:2b246322:start=1550057590479020959,finish=1550057590485513088,duration=6492129
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:12e67d0e
$ 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:16992a6a
travis_time:start:16992a6a
$ 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:22e36e6b
$ dmesg | grep -i kill

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[dtolnay]

@rfcbot fcp merge

  impl<T> BinaryHeap<T>
- where
-     T: Ord,
  {
      fn iter(&self) -> Iter<'_, T>;
      fn peek(&self) -> Option<&T>;
      fn capacity(&self) -> usize;
      fn reserve_exact(&mut self, additional: usize);
      fn reserve(&mut self, additional: usize);
      fn shrink_to_fit(&mut self);
      fn shrink_to(&mut self, min_capacity: usize);
      fn into_vec(self) -> Vec<T>;
      fn len(&self) -> usize;
      fn is_empty(&self) -> bool;
      fn drain(&mut self) -> Drain<'_, T>;
      fn clear(&mut self);
  }

  impl<T> Debug for BinaryHeap<T>
  where
      T: Debug,
-     T: Ord;

  impl<T> IntoIterator for BinaryHeap<T>
- where
-     T: Ord;

  impl<'a, T> IntoIterator for &'a BinaryHeap<T>
- where
-     T: Ord;

[rfcbot]

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

• @Kimundi
• @SimonSapin
• @alexcrichton
• @dtolnay
• @sfackler
• @withoutboats

No concerns currently listed.

Once a majority of reviewers approve (and none object), 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]

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

[rfcbot]

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process,I would like to thank @dtolnayfor their work and everyone else who contributed.

The RFC will be merged soon.

[dtolnay]

Thanks @nox!

[dtolnay]

@bors r+

[bors]

📌 Commit ac32359 has been approved by dtolnay