===================================================================
@@ -1597,6 +1597,9 @@
// level.
_M_rehash_policy._M_prev_resize = 0;
}
+ else
+ // No rehash, restore previous state to keep a consistent state.
+ _M_rehash_policy._M_reset(__saved_state);
}
template<typename _Key, typename _Value,
===================================================================
@@ -40,8 +40,28 @@
}
}
+void test02()
+{
+ const int N = 1000;
+
+ typedef std::unordered_set<int> Set;
+ Set s;
+ s.reserve(N);
+ s.reserve(N);
+
+ std::size_t bkts = s.bucket_count();
+ for (int i = 0; i != N; ++i)
+ {
+ s.insert(i);
+ // As long as we insert less than the reserved number of elements we
+ // shouldn't experiment any rehash.
+ VERIFY( s.bucket_count() == bkts );
+ }
+}
+
int main()
{
test01();
+ test02();
return 0;
}
Here is the patch to fix the redundant rehash/reserve issue. 2012-11-07 François Dumont <fdumont@gcc.gnu.org> PR libstdc++/54075 * include/bits/hashtable.h (_Hashtable<>::rehash): Reset hash policy state if no rehash. * testsuite/23_containers/unordered_set/modifiers/reserve.cc (test02): New. I had prepared and tested it in 4.7 branch but I can apply the same on trunk. Ok to commit ? If so, where ? François On 11/06/2012 10:33 PM, paolo.carlini at oracle dot com wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54075 > > --- Comment #39 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-11-06 21:33:57 UTC --- > Ok thanks. I guess depending on the complexity of the fixes we can apply some > only to mainline first and reconsider the 4_7 branch later. Please do your best > to work on both issues: we just entered Stage 3 thus no new features from now > on, we are all concentrated on bug fixes until the release. >