experimental support for preserving local variable names in the generated code

compiler/ast.nim

@@ -244,12 +244,17 @@ const
   sfDispatcher* = sfDeadCodeElim # copied method symbol is the dispatcher
   sfNoInit* = sfMainModule       # don't generate code to init the variable
 
-  sfImmediate* = sfDeadCodeElim  # macro or template is immediately expanded
-                                 # without considering any possible overloads
+  sfImmediate* = sfDeadCodeElim
+    # macro or template is immediately expanded
+    # without considering any possible overloads
   
-  sfAnon* = sfCompilerProc  # symbol name that was generated by the compiler
-                            # the compiler will avoid printing such names 
-                            # in user messages.
+  sfAnon* = sfDiscardable
+    # symbol name that was generated by the compiler
+    # the compiler will avoid printing such names 
+    # in user messages.
+  
+  sfShadowed* = sfInnerProc
+    # a variable that was shadowed in some inner scope
 
 const
   # getting ready for the future expr/stmt merge
@@ -647,6 +652,14 @@ const
   resultPos* = 5
   dispatcherPos* = 6 # caution: if method has no 'result' it can be position 5!
 
+  nkCallKinds* = {nkCall, nkInfix, nkPrefix, nkPostfix,
+                  nkCommand, nkCallStrLit}
+
+  nkLambdaKinds* = {nkLambda, nkDo}
+
+  skLocalVars* = {skVar, skLet, skForVar, skParam}
+
+
 # creator procs:
 proc NewSym*(symKind: TSymKind, Name: PIdent, owner: PSym): PSym
 proc NewType*(kind: TTypeKind, owner: PSym): PType
@@ -691,11 +704,6 @@ proc copyNode*(src: PNode): PNode
 proc copyTree*(src: PNode): PNode
   # does copy its sons!
 
-const nkCallKinds* = {nkCall, nkInfix, nkPrefix, nkPostfix, nkCommand,
-                      nkCallStrLit}
-
-const nkLambdaKinds* = {nkLambda, nkDo}
-
 proc isCallExpr*(n: PNode): bool =
   result = n.kind in nkCallKinds