added warning for confusing var declarations

compiler/transf.nim

@@ -244,7 +244,16 @@ proc transformConstSection(c: PTransf, v: PNode): PTransNode =
         result[i] = PTransNode(b)
       else:
         result[i] = PTransNode(it)
-  
+
+proc trivialBody(s: PSym): PNode =
+  # a routine's body is trivially inlinable if marked as 'inline' and its
+  # body consists of only 1 statement. It is important that we perform this
+  # optimization here as 'distinct strings' may cause string copying otherwise:
+  # proc xml(s: string): TXmlString = return xmlstring(s)
+  # We have to generate a ``nkLineTracking`` node though to not lose
+  # debug information:
+  # XXX to implement
+  nil
 
 proc hasContinue(n: PNode): bool = 
   case n.kind