Warning when building with NDEBUG

[L0PiTaL]

Describe the bug
The compiler emits a warning when building with NDEBUG, due to expanding NNI_ASSERT to (0)

Expected behavior
No warnings

Actual Behavior
Warnings emited

To Reproduce
Just build the lib in release mode (or with NDEBUG set)

[ori-d]

I think this can be replaced with just emty define like
#define NNI_ASSERT(x)
That's all.

[L0PiTaL]

@ori-d
yes, there are a lot of ways to fix this. The PR is just one of them, which doesn't alter the current behavior, which is just to introduce a (0) instruction (which leads to a no-op). It just silences the diagnostic caused by this instruction.

By the way, with your fix, I think that it silences the diagnostic "empty instruction", but it would emit another diagnostic, "empty statement":
NNI_ASSERT(whatever); //Note the last semicolon, so NNI_ASSERT() can be treated as a "normal" function

would be expanded to:
; //nothing, but the semicolon remains

which now emits the "empty statement" diagnostic.
While with the solution in the PR, it expands to:
((void)(0));

which is a silenced empty instruction (so no diagnostic for this one, as it is silenced), and also not an empty statement (so it neither emits the other diagnostic).

[gdamore]

#1622 fixes this.

You can't elide away the (0) ... because it may be used in a context where we have to have a valid statement.