Does the spec take priority over the compiler?

[Neia Neutuladh]

When the spec says that one thing should happen and the compiler does 
something different, should we generally take the spec to be correct, or 
should we take the compiler to be correct? Do we need to ask Walter every 
time, or go spelunking through github comments and the newsgroup to figure 
it out?

When we want to change the compiler to be in line with the spec, does that 
require a DIP? When we want to change the spec to be in line with the 
compiler, does that require a DIP?

The specific question here is whether attributes like @nogc should 
propagate into nested declarations the same as @trusted (as the spec says) 
or not (as the compiler implements).