Potential "false positive" performance warning

[Tobias Markus]

Again, this is the perfetto source code from https://github.com/google/perfetto

src/protozero/filtering/filter_util.cc:328:28: performance: Searching before insertion is not necessary. [stlFindInsert]
          seen_msgs.insert(nested_type);

The code is as follows:

        if (seen_msgs.find(nested_type) == seen_msgs.end()) {
          seen_msgs.insert(nested_type);
          queue.emplace_back(result.nested_msg_index, nested_type);
        }

While I can understand the reason for the warning, the emplace_back command does depend on it, so the find statement can't be removed in any case.

[CHR]

How about this?

void f(std::set<int>& s, int i) {
    auto [_, b] = s.insert(i);
    if (b) {
        dostuff();
    }
}