1869256 - Compile error calling std::swap on SegmentedVectors

Status: RESOLVED FIXED

(Core :: MFBT, defect)

Description

[Jon Coppeard (:jonco) (PTO until 27th Jan)]

I'd like to swap two segmented vectors but this doesn't compile:

/home/jon/clone/semi/mfbt/tests/TestSegmentedVector.cpp:140:3: error: no matching function for call to 'swap'
  140 |   std::swap(v, w);
      |   ^~~~~~~~~
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/move.h:182:5: note: candidate template ignored: requirement '__and_<std::__not_<std::__is_tuple_like<mozilla::SegmentedVector<int, 32, InfallibleAllocPolicy>>>, std::is_move_constructible<mozilla::SegmentedVector<int, 32, InfallibleAllocPolicy>>, std::is_move_assignable<mozilla::SegmentedVector<int, 32, InfallibleAllocPolicy>>>::value' was not satisfied [with _Tp = MyVector]
  182 |     swap(_Tp& __a, _Tp& __b)
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/move.h:205:5: note: candidate template ignored: could not match '_Tp[_Nm]' against 'MyVector' (aka 'SegmentedVector<int, 32, InfallibleAllocPolicy>')
  205 |     swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/stl_pair.h:495:5: note: candidate template ignored: could not match 'pair' against 'SegmentedVector'
  495 |     swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/stl_pair.h:503:5: note: candidate template ignored: could not match 'pair' against 'SegmentedVector'
  503 |     swap(pair<_T1, _T2>&, pair<_T1, _T2>&) = delete;
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/basic_string.h:6285:5: note: candidate template ignored: could not match 'basic_string' against 'SegmentedVector'
 6285 |     swap(basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/array:294:5: note: candidate template ignored: could not match 'array' against 'SegmentedVector'
  294 |     swap(array<_Tp, _Nm>& __one, array<_Tp, _Nm>& __two)
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/array:302:5: note: candidate template ignored: could not match 'array' against 'SegmentedVector'
  302 |     swap(array<_Tp, _Nm>&, array<_Tp, _Nm>&) = delete;
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/tuple:1618:5: note: candidate template ignored: could not match 'tuple' against 'SegmentedVector'
 1618 |     swap(tuple<_Elements...>& __x, tuple<_Elements...>& __y)
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/tuple:1625:5: note: candidate template ignored: could not match 'tuple' against 'SegmentedVector'
 1625 |     swap(tuple<_Elements...>&, tuple<_Elements...>&) = delete;
      |     ^
/home/jon/clone/semi/optdebug-build/dist/include/mozilla/CompactPair.h:238:6: note: candidate template ignored: could not match 'CompactPair' against 'SegmentedVector'
  238 | void swap(mozilla::CompactPair<A, B>& aX, mozilla::CompactPair<A, B>& aY) {
      |      ^
/home/jon/clone/semi/optdebug-build/dist/include/mozilla/UniquePtr.h:642:6: note: candidate template ignored: could not match 'UniquePtr' against 'SegmentedVector'
  642 | void swap(mozilla::UniquePtr<T, D>& aX, mozilla::UniquePtr<T, D>& aY) {
      |      ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/sstream:797:5: note: candidate template ignored: could not match 'basic_stringbuf' against 'SegmentedVector'
  797 |     swap(basic_stringbuf<_CharT, _Traits, _Allocator>& __x,
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/sstream:804:5: note: candidate template ignored: could not match 'basic_istringstream' against 'SegmentedVector'
  804 |     swap(basic_istringstream<_CharT, _Traits, _Allocator>& __x,
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/sstream:811:5: note: candidate template ignored: could not match 'basic_ostringstream' against 'SegmentedVector'
  811 |     swap(basic_ostringstream<_CharT, _Traits, _Allocator>& __x,
      |     ^
/home/jon/.mozbuild/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/sstream:818:5: note: candidate template ignored: could not match 'basic_stringstream' against 'SegmentedVector'
  818 |     swap(basic_stringstream<_CharT, _Traits, _Allocator>& __x,
      |     ^
1 error generated.

Comment 1

[Jon Coppeard (:jonco) (PTO until 27th Jan)]

Attachment: Bug 1869256 - Add move assignment operator for SegmentedVector r?mccr8

The patch implements the move assigment operator in terms of the move
constructor. This fulfills the requirements for std::swap to compile.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d404928e57cf
Add move assignment operator for SegmentedVector r=mccr8

Comment 3

[Norisz Fay [:noriszfay]]

Backed out for causing bustages on TestSegmentedVector.cpp

Backout link

Push with failures

Failure log

Comment 4

[Andrew McCreight [:mccr8]]

Weird. I didn't know that was a thing we warned against.

Comment 5

[Jon Coppeard (:jonco) (PTO until 27th Jan)]

My neither, TIL :)

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/cb63408380d2
Add move assignment operator for SegmentedVector r=mccr8

Comment 7

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/cb63408380d2