Search code examples
gpumetal

Why does Metal compile this recursive function?

The Metal spec says that recursive functions are not allowed. However this compiles fine:

int b(int c) {
  if (c == 1)
    return b(c++);
  else if (c == 2)
    return b(c + 2);
  else
    return c;
}

Why is that? What is the definition of recursive that Metal is using? It refers to section 5.2.2 of the C++14 spec, which also does not give any definition of "recursive" thus I'd expect the above to be a standard example of recursion.

Even if I do this, it still compiles:

int b(int c) {
    return b(c + 2);
}

What gives?!

Solution

  • The function can compile fine like any C++ function, no problem. It's when you call the function from a kernel that you will get a compile error about recursive function use.