Merge pull request #11654 from alalek:issue_11648

modules/core/include/opencv2/core/cvstd.inl.hpp

@@ -76,13 +76,10 @@ public:
 inline
 String::String(const std::string& str)
     : cstr_(0), len_(0)
-{
-    if (!str.empty())
 {
     size_t len = str.size();
     if (len) memcpy(allocate(len), str.c_str(), len);
 }
-}
 
 inline
 String::String(const std::string& str, size_t pos, size_t len)
@@ -99,11 +96,8 @@ inline
 String& String::operator = (const std::string& str)
 {
     deallocate();
-    if (!str.empty())
-    {
     size_t len = str.size();
     if (len) memcpy(allocate(len), str.c_str(), len);
-    }
     return *this;
 }