https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108554
Bug ID: 108554
Summary: Warning "null pointer dereferece" raised when
extracting a unique_ptr from a map and any "-O" flag
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: fcontact at cuveland dot de
Target Milestone: ---
I found what I believe might be a false positive with g++ 12 when using the
"-Wnull-dereference" warning and a map of unique_ptr with any level of
optimisation.
This behavior does not show up in GCC 9, 10, and 11.
Small but complete example:
#include <map>
#include <memory>
#include <string>
#include <utility>
int main()
{
// create and initialize a map
std::map<std::string, std::unique_ptr<int>> my_map;
my_map["my_key"] = std::make_unique<int>(1);
auto it = my_map.find("my_key");
if (it != my_map.end()) {
// extract an item from the map
auto item = std::move(my_map.extract(it).mapped());
return *item;
}
return 0;
}
Compiled with:
g++-12 -O -Wnull-dereference <filename>
Compiler version:
g++ (Compiler-Explorer-Build-gcc--binutils-2.38) 12.2.0
(see https://godbolt.org/z/E9KhTT4f6)
