Possible FP in [invalidLifetime] with string_view

[ashimaru]

When uplifting to cppcheck 2.9 I got report on this code:

#include <string_view>
#include <string>
#include <charconv>

std::string getValue()
{
    return "123";
}

template<class T>
T textToNumber(std::string_view text)
{
    T result{};
    std::from_chars(text.data(), text.data() + text.size(), result); //Using object that points to local variable 'str' that is out of scope. [invalidLifetime]
    return result;
}

int f()
{
    const auto str = getValue(); //Variable created here.
    return textToNumber<int>(str);
}

For me it looks like FP since str is not out of range.
You can find full file in the attachment

Have a great day!

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/11508

[ashimaru]

Hi again!
I am trying to investigate this issue and managed to simplify this issue further:

int textToNumber(std::string_view text);
void f() {
    std::string teststr;
    textToNumber(teststr);
}

void textToNumber(std::string_view text) {
    g(text.data());
}

I also did some digging around and it seems that in condition in checkautovariables.cpp:588 (as for f16ffd88e96efc4ab5a538fa61197741be6fee3b) marks error because 'textToNumber' function's scope ends after 'f''s end of scope.

This issue is not visible if std::string_view is replaced with const std::string&. I am not sure how to apporach it, should std::string_view be translated into a reference or a pointer to original string?