IC based on NIF feature

compiler/ast.nim

@@ -692,10 +692,15 @@ type
 
   PScope* = ref TScope
 
+  ItemState* = enum
+    Complete # completely in memory
+    Partial  # partially in memory
+
   PLib* = ref TLib
   TSym* {.acyclic.} = object # Keep in sync with PackedSym
     itemId*: ItemId
     # proc and type instantiations are cached in the generic symbol
+    state*: ItemState
     case kind*: TSymKind
     of routineKinds:
       #procInstCache*: seq[PInstantiation]
@@ -770,6 +775,7 @@ type
                               # Keep in sync with PackedType
     itemId*: ItemId
     kind*: TTypeKind          # kind of type
+    state*: ItemState
     callConv*: TCallingConvention # for procs
     flags*: TTypeFlags        # flags of the type
     sons: TTypeSeq           # base types, etc.
@@ -786,7 +792,7 @@ type
     sym*: PSym                # types have the sym associated with them
                               # it is used for converting types to strings
     size*: BiggestInt         # the size of the type in bytes
-                              # -1 means that the size is unkwown
+                              # -1 means that the size is unknown
     align*: int16             # the type's alignment requirements
     paddingAtEnd*: int16      #
     loc*: TLoc