For this case study, we will debug a WebAssembly module generated from a C++ code that conducts an out-of-bounds array access, which is a common error in various programming languages.

Consider the following C++ code:

1#include <iostream>
2using namespace std;
3
4int main() {
5  // Invalid array index access
6  int arr[5] = {1, 2, 3, 4, 5};
7  int x = arr[10];
8  cout << "The accessed value is: " << x << endl;
9  return 0;
10}

This code attempts to access an index that is out of bounds for the given array. In a local machine, this would often result in a segmentation fault, indicating an error. When compiled into a WebAssembly module and run in the browser, it further complicates the error debugging as it's not easy to find the source of the error with conventional JavaScript debugging tools due to the inherent complexity of WebAssembly.

We will use a mixture of C++ debugging tools like gdb and browser-based WebAssembly debugging tools to tackle this issue. These advanced debugging techniques allow us to inspect the variables and call stack, providing a comprehensive view of our application state at the point of error. This method aids in depicting complex problems and discovering solutions effectively.

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#include <iostream>

using namespace std;

​

int main() {

  // Invalid array index access

  int arr[5] = {1, 2, 3, 4, 5};

  int x = arr[10];

  cout << "The accessed value is: " << x << endl;

  return 0;

}