FP returnDanglingLifetime when passing c_str() to function

[chrchr]

​https://sourceforge.net/p/cppcheck/discussion/general/thread/5780274772/:

std::string to_string(const char* str) {
    return str;
}

std::string get() {
    std::string local;
    return to_string(local.c_str());
}

test.cpp:10:21: error: Returning object that points to local variable 'local' that will be invalid when returning. [returnDanglingLifetime]
    return to_string(local.c_str());
                    ^
test.cpp:10:33: note: Pointer to container is created here.
    return to_string(local.c_str());
                                ^
test.cpp:10:33: note: Passed to 'to_string'.
    return to_string(local.c_str());
                                ^
test.cpp:9:17: note: Variable created here.
    std::string local;
                ^
test.cpp:10:21: note: Returning object that points to local variable 'local' that will be invalid when returning.
    return to_string(local.c_str());
                    ^

[kidkat]

This was reported from 1.89 to 2.0 and again since 2.1. It has been bisected to ​https://github.com/cppcheck-opensource/cppcheck/commit/3f1f62e0788c8cf96284e65dcf4af0ee7ca5af8b.

[chrchr]

Fixed by ​https://github.com/cppcheck-opensource/cppcheck/pull/8750