[C++] ListArray comparison is incorrect

[asfimport]

Equality comparison for ListArray accounts for offsets incorrectly, so slices of ListArrays with identical offsets but differing values will sometimes compare equal.

For example, the following test fails:

TEST_F(TestListArray, ValuesEquality) {
  auto type = list(int32());
  auto left = ArrayFromJSON(type, "[[1, 2], [3, null], [5], []]");
  auto right = ArrayFromJSON(type, "[[1, 2], [3, null], [9], []]");

  AssertArraysEqual(*left->Slice(2), *right->Slice(2));
}

Reporter: Ben Kietzman / @bkietz
Assignee: Ben Kietzman / @bkietz

Related issues:

• [C++] Implement Fixed Size List type (is superceded by)

_{Note: This issue was originally created as ARROW-5299. Please see the migration documentation for further details.}

[asfimport]

Ben Kietzman / @bkietz:
Resolved as a drive by in pull 4278 https://github.com/apache/arrow/pull/4278/files#diff-651c90e7833d833bab85492c313bf3feR587