allowing definitions of procs and templates to be overridden in local scopes

compiler/lookups.nim

@@ -164,7 +164,7 @@ proc QualifiedLookUp*(c: PContext, n: PNode, flags = {checkUndeclared}): PSym =
     result = nil
   if result != nil and result.kind == skStub: loadStub(result)
   
-proc InitOverloadIter*(o: var TOverloadIter, c: PContext, n: PNode): PSym = 
+proc InitOverloadIter*(o: var TOverloadIter, c: PContext, n: PNode): PSym =
   case n.kind
   of nkIdent, nkAccQuoted:
     var ident = considerAcc(n)
@@ -174,7 +174,7 @@ proc InitOverloadIter*(o: var TOverloadIter, c: PContext, n: PNode): PSym =
       dec(o.stackPtr)
       if o.stackPtr < 0: break
       result = InitIdentIter(o.it, c.tab.stack[o.stackPtr], ident)
-  of nkSym: 
+  of nkSym:
     result = n.sym
     o.mode = oimDone
   of nkDotExpr: 
@@ -204,6 +204,13 @@ proc InitOverloadIter*(o: var TOverloadIter, c: PContext, n: PNode): PSym =
     Incl(o.inSymChoice, result.id)
   else: nil
   if result != nil and result.kind == skStub: loadStub(result)
+
+proc lastOverloadScope*(o: TOverloadIter): int =
+  case o.mode
+  of oimNoQualifier: result = o.stackPtr
+  of oimSelfModule:  result = ModuleTablePos
+  of oimOtherModule: result = ImportTablePos
+  else: result = -1
   
 proc nextOverloadIter*(o: var TOverloadIter, c: PContext, n: PNode): PSym = 
   case o.mode

compiler/semcall.nim

@@ -36,14 +36,15 @@ proc resolveOverloads(c: PContext, n, orig: PNode,
   template best: expr = result
   #Message(n.info, warnUser, renderTree(n))
   var sym = initOverloadIter(o, c, f)
+  var symScope = o.lastOverloadScope
   
-  if sym == nil: return 
-  initCandidate(best, sym, initialBinding)
-  initCandidate(alt, sym, initialBinding)
+  if sym == nil: return
+  initCandidate(best, sym, initialBinding, symScope)
+  initCandidate(alt, sym, initialBinding, symScope)
 
   while sym != nil:
     if sym.kind in filter:
-      initCandidate(z, sym, initialBinding)
+      initCandidate(z, sym, initialBinding, o.lastOverloadScope)
       z.calleeSym = sym
       matches(c, n, orig, z)
       if z.state == csMatch:

compiler/sigmatch.nim

@@ -27,6 +27,7 @@ type
     state*: TCandidateState
     callee*: PType           # may not be nil!
     calleeSym*: PSym         # may be nil
+    calleeScope: int         # may be -1 for unknown scope
     call*: PNode             # modified call
     bindings*: TIdTable      # maps types to types
     baseTypeMatch: bool      # needed for conversions from T to openarray[T]
@@ -60,9 +61,10 @@ proc put(t: var TIdTable, key, val: PType) {.inline.} =
         IdentEq(val.sym.name, "TTable"):
       assert false
 
-proc initCandidate*(c: var TCandidate, callee: PSym, binding: PNode) = 
+proc initCandidate*(c: var TCandidate, callee: PSym, binding: PNode, calleeScope = -1) = 
   initCandidateAux(c, callee.typ)
   c.calleeSym = callee
+  c.calleeScope = calleeScope
   initIdTable(c.bindings)
   if binding != nil:
     var typeParams = callee.ast[genericParamsPos]
@@ -94,6 +96,9 @@ proc cmpCandidates*(a, b: TCandidate): int =
   result = a.intConvMatches - b.intConvMatches
   if result != 0: return
   result = a.convMatches - b.convMatches
+  if result != 0: return
+  if (a.calleeScope != -1) and (b.calleeScope != -1):
+    result = a.calleeScope - b.calleeScope
 
 proc writeMatches(c: TCandidate) = 
   Writeln(stdout, "exact matches: " & $c.exactMatches)