preparations for another bugfix

compiler/semcall.nim

@@ -90,6 +90,10 @@ proc pickBestCandidate(c: PContext, headSymbol: PNode,
     if c.currentScope.symbols.counter == counterInitial or syms != nil:
       matches(c, n, orig, z)
       if z.state == csMatch:
+        #if sym.name.s == "==" and (n.info ?? "temp3"):
+        #  echo typeToString(sym.typ)
+        #  writeMatches(z)
+
         # little hack so that iterators are preferred over everything else:
         if sym.kind == skIterator: inc(z.exactMatches, 200)
         case best.state

compiler/sigmatch.nim

@@ -224,7 +224,8 @@ proc complexDisambiguation(a, b: PType): int =
     let x = a.sons[i].sumGeneric
     let y = b.sons[i].sumGeneric
     #if ggDebug:
-    #  echo "came her ", typeToString(a.sons[i]), " ", typeToString(b.sons[i])
+    #echo "came herA ", typeToString(a.sons[i]), " ", x
+    #echo "came herB ", typeToString(b.sons[i]), " ", y
     if x != y:
       if winner == 0:
         if x > y: winner = 1
@@ -1550,11 +1551,21 @@ proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
           result = isNone
       else:
         if f.sonsLen > 0 and f.sons[0].kind != tyNone:
+          when false:
+            let oldInheritancePenalty = c.inheritancePenalty
           result = typeRel(c, f.lastSon, a, flags + {trDontBind})
           if doBind and result notin {isNone, isGeneric}:
             let concrete = concreteType(c, a)
             if concrete == nil: return isNone
             put(c, f, concrete)
+          when false:
+            # bug #6526
+            if result in {isEqual, isSubtype}:
+              # 'T: Class' is a *better* match than just 'T'
+              # but 'T: Subclass' is even better:
+              c.inheritancePenalty = oldInheritancePenalty - c.inheritancePenalty -
+                                    100 * ord(result == isEqual)
+              result = isGeneric
         else:
           result = isGeneric