first implementation of overloading of '='; missing: rewriting let/var sections

compiler/semexprs.nim

@@ -1233,6 +1233,8 @@ proc asgnToResultVar(c: PContext, n, le, ri: PNode) {.inline.} =
 template resultTypeIsInferrable(typ: PType): expr =
   typ.isMetaType and typ.kind != tyTypeDesc
 
+include semasgn
+
 proc semAsgn(c: PContext, n: PNode): PNode =
   checkSonsLen(n, 2)
   var a = n.sons[0]
@@ -1298,6 +1300,9 @@ proc semAsgn(c: PContext, n: PNode): PNode =
           typeMismatch(n, lhs.typ, rhs.typ)
 
     n.sons[1] = fitNode(c, le, rhs)
+    if tfHasAsgn in lhs.typ.flags and not lhsIsResult:
+      return overloadedAsgn(c, lhs, n.sons[1])
+
     fixAbstractType(c, n)
     asgnToResultVar(c, n, n.sons[0], n.sons[1])
   result = n