How do I diagnose 'stack-use-after-return' with ASan in C++?

'stack-use-after-return' is a type of error that occurs when a program uses a variable that has already been deallocated, leading to undefined behavior. AddressSanitizer (ASan) is a memory error detector that can help diagnose these issues in C++. Here's how you can use ASan to find and fix 'stack-use-after-return' errors:

Steps to Diagnose

1. Compile your program with ASan enabled. You can do this by adding the flag -fsanitize=address during compilation.
2. Run your program. If an error related to 'stack-use-after-return' occurs, ASan will provide a detailed report.
3. Analyze the stack trace given by ASan to identify the location of the problematic code.
4. Review your code logic and ensure that you are not accessing variables out of their scope.

Example

#include <iostream>

void exampleFunction() {
    int value = 10;
    int *ptr = &value;
    return; // value goes out of scope here
}

int main() {
    exampleFunction();
    std::cout << *ptr; // Using ptr after the stack frame is gone
    return 0;
}