Reflector gets wrong decompiling result?

[chants]

However, if the referenced value (b) is unused, in all caller contexts which invoke this function, then theoretically

b += 4

can be optimized out. Of course with reflection or exporting that would be somewhat impossible to deduce but these sorts of assumptions are more complicated issues even the compiler has to make decisions about and usually documented vaguely somewhere as to what guarantees are provided.