[Bug middle-end/90959] New: hash_map can be copied but leads to a double-free after assignment

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90959

            Bug ID: 90959
           Summary: hash_map can be copied but leads to a double-free
                    after assignment
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

While beefing up the tests for bug 90923 I came across yet another bug in
hash_map.  The container defines a copy ctor but no assignment operator, and so
while copying a container of PODs seems to do the right thing, assigning one to
another makes them share storage and ultimately leads to a double free.  Below
is a simple test case that demonstrates this:

  {
    typedef hash_map <void*, int> Map;

    {
      Map m1;
      void *p = &p;
      m1.put (p, 1);

      Map m2;
      m2 = m1;
    }

    Map m3;
  }
double free or corruption (!prev)
cc1: internal compiler error: Aborted
0x11a4b99 crash_signal
        /src/gcc/git-svn/gcc/toplev.c:326
0x21447f9 xcallocator<hash_map<void*, int,
simple_hashmap_traits<default_hash_traits<void*>, int>
>::hash_entry>::data_free(hash_map<void*, int,
simple_hashmap_traits<default_hash_traits<void*>, int> >::hash_entry*)
        /src/gcc/git-svn/gcc/hash-table.h:282
0x21439ab hash_table<hash_map<void*, int,
simple_hashmap_traits<default_hash_traits<void*>, int> >::hash_entry, false,
xcallocator>::~hash_table()
        /src/gcc/git-svn/gcc/hash-table.h:677
0x2143421 hash_map<void*, int,
simple_hashmap_traits<default_hash_traits<void*>, int> >::~hash_map()
        /src/gcc/git-svn/gcc/hash-map.h:30
0x2140e18 test_map_of_type_with_ctor_and_dtor
        /src/gcc/git-svn/gcc/hash-map-tests.c:152
0x2141e3d selftest::hash_map_tests_c_tests()
        /src/gcc/git-svn/gcc/hash-map-tests.c:257
0x20da1c5 selftest::run_tests()
        /src/gcc/git-svn/gcc/selftest-run-tests.c:64
0x11a89ec toplev::run_self_tests()
        /src/gcc/git-svn/gcc/toplev.c:2273