.NET compiler and “Not all code paths return a value”

Question

Why in code like below is the .NET compiler not able to establish that all code paths do return a value?

bool Test(bool param) {
    bool test = true;
    if         


        

Answer 1

From Eric Lippert's blog:

The reachability analyzer is not very smart. It does not realize that there are only two possible control flows and that we've covered all of them with returns.

^{(The blog post is on switch statements, but I guess the reachability analyzer isn't much smarter for if statements.)}