DMD semantic passes overview?

[Nick Sabalausky]

I don't suppose there's any information out there on how DMD's sematic 
passes work? (esp, regarding types, forward reference resolution and 
DSymbol::scope as used by AggregateDeclaration, but I suppose getting that 
specific might be asking too much).

I've been digging through the code, and so far what I've been able to grok 
is that there's theree passes (semantic, semantic2 and semantic3), each node 
in the AST tries to run the (same) semantic pass for it's own members and 
for anything they reference, and during the first pass some stuff gets 
deferred to right after the first pass.

I'll keep digging though, but any help would be, umm, helpful :)