fixes #544

compiler/semfold.nim

@@ -625,6 +625,10 @@ proc getConstExpr(m: PSym, n: PNode): PNode =
           result = newIntNodeT(sonsLen(a), n)
         else:
           result = magicCall(m, n)
+      of mLengthArray:
+        # It doesn't matter if the argument is const or not for mLengthArray.
+        # This fixes bug #544.
+        result = newIntNodeT(lengthOrd(n.sons[1].typ), n)
       of mAstToStr:
         result = newStrNodeT(renderTree(n[1], {renderNoComments}), n)
       of mConStrStr:

compiler/semtypes.nim

@@ -841,7 +841,9 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
       LocalError(n.info, errTypeExpected)
       result = newOrPrevType(tyError, prev, c)
   of nkCallKinds:
-    if n[0].kind == nkIdent:
+    if isRange(n):
+      result = semRangeAux(c, n, prev)
+    elif n[0].kind == nkIdent:
       let op = n.sons[0].ident
       if op.id in {ord(wAnd), ord(wOr)} or op.s == "|":
         checkSonsLen(n, 3)

compiler/types.nim

@@ -959,8 +959,8 @@ proc skipGenericAlias*(t: PType): PType =
 proc matchTypeClass*(bindings: var TIdTable, typeClass, t: PType): bool =
   for i in countup(0, typeClass.sonsLen - 1):
     let req = typeClass.sons[i]
-    var match = req.kind == skipTypes(t, {tyRange, tyGenericInst}).kind
-      
+    var match = req.kind == skipTypes(t, {tyGenericInst, tyRange}).kind or
+                req.kind == skipTypes(t, {tyGenericInst}).kind
     if not match:
       case req.kind
       of tyGenericBody: