Some newly introduced tests in 23_containers/unordered_map/cons/default.cc revealed that we are forcing the allocator type to have a operator==.

It can be avoided by checking allocator_traits::is_always_equal.

    libstdc++: [_GLIBCXX_DEBUG] Avoid allocator operator== when always equal

    Use std::allocator_traits::is_always_equal to find out if we need to compare
    allocator instances on safe container allocator aware move constructor.

    libstdc++-v3/ChangeLog:

            * include/debug/safe_container.h
            (_Safe_container(_Safe_container&&, const _Alloc&, std::true_type)): New.             (_Safe_container(_Safe_container&&, const _Alloc&, std::false_type)): New.             (_Safe_container(_Safe_container&&, const _Alloc&)): Use latters.

Tested under Linux x86 Debug mode.

Ok to commit ?

François

diff --git a/libstdc++-v3/include/debug/safe_container.h b/libstdc++-v3/include/debug/safe_container.h
index d9636c29e9b..b06c33dac7e 100644
--- a/libstdc++-v3/include/debug/safe_container.h
+++ b/libstdc++-v3/include/debug/safe_container.h
@@ -57,7 +57,12 @@ namespace __gnu_debug
       _Safe_container(const _Safe_container&) = default;
       _Safe_container(_Safe_container&&) = default;
 
-      _Safe_container(_Safe_container&& __x, const _Alloc& __a)
+    private:
+      _Safe_container(_Safe_container&& __x, const _Alloc& __a, std::true_type)
+      : _Safe_container()
+      { _Base::_M_swap(__x); }
+
+      _Safe_container(_Safe_container&& __x, const _Alloc& __a, std::false_type)
       : _Safe_container()
       {
 	if (__x._M_cont().get_allocator() == __a)
@@ -65,6 +70,12 @@ namespace __gnu_debug
 	else
 	  __x._M_invalidate_all();
       }
+
+    protected:
+      _Safe_container(_Safe_container&& __x, const _Alloc& __a)
+      : _Safe_container(std::move(__x), __a,
+		      typename std::allocator_traits<_Alloc>::is_always_equal{})
+      { }
 #endif
 
     public:

Reply via email to