Re: [v3 PATCH] PR libstdc++/78389

[Ville Voutilainen]

On 15 January 2017 at 19:01, Ville Voutilainen
<ville.voutilai...@gmail.com> wrote:
> On 15 January 2017 at 18:42, Tim Song <t.canens....@gmail.com> wrote:
>> On rereading the patch today, the size calculation for merge() appears
>> to be backwards. [__first2, __last2) consists of the nodes not
>> transferred into *this, so the new size of __x should be __dist while
>> this->size() should be incremented by (__orig_size - __dist).
>
> Ah, yes, I'm an idiot. Fixing...

2017-01-15  Ville Voutilainen  <ville.voutilai...@gmail.com>

    PR libstdc++/78389
    Fix backwards size adjustments.
    * include/bits/list.tcc (merge(list&&)):
    Fix backwards size adjustments.
    (merge(list&&, _StrictWeakOrdering)): Likewise.
    * testsuite/23_containers/list/operations/78389.cc: Add
    better test for the sizes.

diff --git a/libstdc++-v3/include/bits/list.tcc 
b/libstdc++-v3/include/bits/list.tcc
index 5be49a8..d80d569 100644
--- a/libstdc++-v3/include/bits/list.tcc
+++ b/libstdc++-v3/include/bits/list.tcc
@@ -406,8 +406,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
          __catch(...)
            {
              size_t __dist = std::distance(__first2, __last2);
-             this->_M_inc_size(__dist);
-             __x._M_set_size(__orig_size - __dist);
+             this->_M_inc_size(__orig_size - __dist);
+             __x._M_set_size(__dist);
              __throw_exception_again;
            }
        }
@@ -454,8 +454,8 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
            __catch(...)
              {
                size_t __dist = std::distance(__first2, __last2);
-               this->_M_inc_size(__dist);
-               __x._M_set_size(__orig_size - __dist);
+               this->_M_inc_size(__orig_size - __dist);
+               __x._M_set_size(__dist);
                __throw_exception_again;
              }
          }
diff --git a/libstdc++-v3/testsuite/23_containers/list/operations/78389.cc 
b/libstdc++-v3/testsuite/23_containers/list/operations/78389.cc
index 1cf9b0c..3002ba6 100644
--- a/libstdc++-v3/testsuite/23_containers/list/operations/78389.cc
+++ b/libstdc++-v3/testsuite/23_containers/list/operations/78389.cc
@@ -61,6 +61,8 @@ int main()
   } catch (...) {
   }
   VERIFY(a.size() == 8 && b.size() == 4);
+  VERIFY(a.size() == std::distance(a.begin(), a.end()) &&
+        b.size() == std::distance(b.begin(), b.end()));
   std::list<X> ax{1, 2, 3, 4};
   std::list<X> bx{5, 6, 7, 8, 9, 10, 11, 12};
   throw_after_X = 5;
@@ -69,6 +71,8 @@ int main()
   } catch (...) {
   }
   VERIFY(ax.size() == 8 && bx.size() == 4);
+  VERIFY(ax.size() == std::distance(ax.begin(), ax.end()) &&
+        bx.size() == std::distance(bx.begin(), bx.end()));
   std::list<int> ay{5, 6, 7, 8, 9, 10, 11, 12};
   try {
     ay.sort(ThrowingComparator{5});