[Bug libstdc++/56267] New: [4.7/4.8 Regression] unordered containers require Assignable hash function

[Bug libstdc++/56267] New: [4.7/4.8 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

             Bug #: 56267
           Summary: [4.7/4.8 Regression] unordered containers require
                    Assignable hash function
    Classification: Unclassified
           Product: gcc
           Version: 4.7.3
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: redi@gcc.gnu.org


\x01\x01#include <unordered_set>

struct hash : std::hash<int>
{
  hash& operator=(const hash&) = delete;
};

int main()
{
  std::unordered_set<int, hash> s{ 0, 1, 2 };
  auto i = s.begin(0);
  i = i;
}


The standard does not require hash functions to be assignable.

We must cache the hash code unless is_copy_assignable<H> is true, I'm testing
the fix.

[Bug libstdc++/56267] [4.7/4.8 Regression] unordered containers require Assignable hash function

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.3

[Bug libstdc++/56267] [4.7/4.8 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot       |redi at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-10 21:57:10 UTC ---
To be really annoying, a hash function could do this:

#include <unordered_set>

struct hash : std::hash<int>
{
  hash() { throw 1; }
  hash(int) { }
};

int main()
{
  std::unordered_set<int, hash>::local_iterator i;
}

We can't detect this at compile-time, so it will fail at runtime.

The Hash requirements only include CopyConstructible and Destructible, so we
should not rely on CopyAssignable or DefaultConstructible, so the local
iterator type should really use placement new to copy-construct the hash
function in an aligned_storage buffer, and on assignment destroy it and
copy-construct a new object using placement new again.

[Bug libstdc++/56267] [4.7/4.8 Regression] unordered containers require Assignable hash function

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2013-02-10 23:00:34 UTC ---
Thanks Jon for fully handling this. I understand that in principle we could
have checked is_nothrow_default_constructible, but it's of course much better
if we can just use operations guaranteed by the Standard and be done with it.
If you remember, the is_default_constructible check made me a little nervous
from the start...

[Bug libstdc++/56267] [4.7/4.8 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-11 00:19:42 UTC ---
Author: redi
Date: Mon Feb 11 00:19:29 2013
New Revision: 195936

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=195936
Log:
    PR libstdc++/56267
    * include/bits/hashtable.h (__cache_default): Check if hash function
    is copy assignable.
    * testsuite/23_containers/unordered_set/56267.cc: New.
    * testsuite/23_containers/unordered_set/instantiation_neg.cc: Adjust
    dg-error line number.
    * testsuite/23_containers/unordered_set/
    not_default_constructible_hash_neg.cc: Likewise.

Added:
    trunk/libstdc++-v3/testsuite/23_containers/unordered_set/56267.cc
      - copied, changed from r195935,
trunk/libstdc++-v3/testsuite/23_containers/unordered_set/instantiation_neg.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/hashtable.h
   
trunk/libstdc++-v3/testsuite/23_containers/unordered_set/instantiation_neg.cc
   
trunk/libstdc++-v3/testsuite/23_containers/unordered_set/not_default_constructible_hash_neg.cc

[Bug libstdc++/56267] [4.7/4.8 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2013-02-11
     Ever Confirmed|0                           |1

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-02-11 00:25:29 UTC ---
The first testcase passes on trunk now, I'm also going to fix that for 4.7.3

Fixing the second testcase will take more work.

[Bug libstdc++/56267] [4.7/4.8 Regression] unordered containers require Assignable hash function

[jsm28 at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

Joseph S. Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug libstdc++/56267] [4.7/4.8/4.9 Regression] unordered containers require Assignable hash function

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.3                       |4.7.4

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> 2013-04-11 07:59:38 UTC ---
GCC 4.7.3 is being released, adjusting target milestone.

[Bug libstdc++/56267] [4.7/4.8/4.9 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Mon Jan 20 15:49:39 2014
New Revision: 206834

URL: http://gcc.gnu.org/viewcvs?rev=206834&root=gcc&view=rev
Log:
    PR libstdc++/56267
    * include/bits/hashtable_policy.h (_Hash_code_base<... false>): Grant
    friendship to _Local_iterator_base<..., false>.
    (_Local_iterator_base): Give protected access to all existing members.
    (_Local_iterator_base::_M_curr()): New public accessor.
    (_Local_iterator_base::_M_get_bucket()): New public accessor.
    (_Local_iterator_base<..., false>::_M_init()): New function to manage
    the lifetime of the _Hash_code_base explicitly.
    (_Local_iterator_base<..., false>::_M_destroy()): Likewise.
    (_Local_iterator_base<..., false>): Define copy constructor and copy
    assignment operator that use new functions to manage _Hash_code_base.
    (operator==(const _Local_iterator_base&, const _Local_iterator_base&),
    operator==(const _Local_iterator_base&, const _Local_iterator_base&)):
    Use public API for _Local_iterator_base.
    * include/debug/safe_local_iterator.h (_Safe_local_iterator): Likewise.
    * include/debug/unordered_map (__debug::unordered_map::erase(),
    __debug::unordered_multimap::erase()): Likewise.
    * include/debug/unordered_set (__debug::unordered_set::erase(),
    __debug::unordered_multiset::erase()): Likewise.
    * testsuite/23_containers/unordered_set/56267-2.cc: New test.

Added:
    trunk/libstdc++-v3/testsuite/23_containers/unordered_set/56267-2.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/hashtable_policy.h
    trunk/libstdc++-v3/include/debug/safe_local_iterator.h
    trunk/libstdc++-v3/include/debug/unordered_map
    trunk/libstdc++-v3/include/debug/unordered_set

[Bug libstdc++/56267] [4.7/4.8/4.9 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|4.7.4                       |4.9.0

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed for 4.9.0, I don't think it's worth backporting to earlier releases

[Bug libstdc++/56267] [4.7/4.8/4.9 Regression] unordered containers require Assignable hash function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56267

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Tue Jan 21 19:38:35 2014
New Revision: 206904

URL: http://gcc.gnu.org/viewcvs?rev=206904&root=gcc&view=rev
Log:
    PR libstdc++/56267
    * include/bits/hashtable.h (__cache_default): Do not depend on
    whether the hash function is DefaultConstructible or CopyAssignable.
    (_Hashtable): Adjust static assertions.
    * doc/xml/manual/containers.xml (containers.unordered.cache): Update.
    * testsuite/23_containers/unordered_set/instantiation_neg.cc: Adjust
    dg-error line number.
    * testsuite/23_containers/unordered_set/
    not_default_constructible_hash_neg.cc: Remove.

Removed:
   
trunk/libstdc++-v3/testsuite/23_containers/unordered_set/not_default_constructible_hash_neg.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/doc/xml/manual/containers.xml
    trunk/libstdc++-v3/include/bits/hashtable.h
   
trunk/libstdc++-v3/testsuite/23_containers/unordered_set/instantiation_neg.cc