STL map insertion efficiency: [] vs. insert

Question

There are two ways of map insertion:

m[key] = val;

Or

m.insert(make_pair(key, val));

My question is, which op

Answer 1

My answer is not on efficiency but on safety, which is relevant to choosing an insertion algorithm:

The [] and insert() calls would trigger destructors of the elements. This may have dangerous side effects if, say, your destructors have critical behaviors inside.

After such a hazard, I stopped relying on STL's implicit lazy insertion features and always use explicit checks if my objects have behaviors in their ctors/dtors.

See this question: Destructor called on object when adding it to std::list