Question

I had, and have since corrected, something like the following code:

class SomeClass {
public:
    static int AdjustValue(float input);
    static int DoSomethingWithAdjustedValue(int adjustedInput);
    static int DoSomethingWithNormalValue(float input) {
        DoSomethingWithAdjustedValue(AdjustValue(input);}
};

So DoSomethingWithNormalValue is clearly missing a return, but GCC did not generate an error or a warning for it. And places where I was calling DoSomethingWithNormalValue were getting the correct return code. I can think of two explanations for this:

1. There is some extension in GCC that recognizes inline functions that are wrapping other functions and passes the return values along.

2. The return code was being passed along because of a lucky/unlucky manifestation of undefined behavior combined with a bug in GCC that prevented any error or warning.

Neither of these strike me as being likely. What is going on here?

Answer 1

try:

> g++ xa1.cpp -Wall
xa1.cpp: In static member function ‘static int SomeClass::DoSomethingWithNormalValue(float)’:
xa1.cpp:8: warning: no return statement in function returning non-void
xa1.cpp:8: warning: control reaches end of non-void function

The return code was being passed along because of a lucky/unlucky manifestation of undefined behavior combined with a bug in GCC that prevented any error or warning.

I think you will find this is what happens.
Technically it is undefined behavior.