fixes #6526

compiler/sigmatch.nim

@@ -1452,8 +1452,13 @@ proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
   of tyOr:
     considerPreviousT:
       result = isNone
+      let oldInheritancePenalty = c.inheritancePenalty
+      var maxInheritance = 0
       for branch in f.sons:
+        c.inheritancePenalty = 0
         let x = typeRel(c, branch, aOrig)
+        maxInheritance = max(maxInheritance, c.inheritancePenalty)
+
         # 'or' implies maximum matching result:
         if x > result: result = x
       if result >= isSubtype:
@@ -1461,6 +1466,7 @@ proc typeRelImpl(c: var TCandidate, f, aOrig: PType,
         bindingRet result
       else:
         result = isNone
+      c.inheritancePenalty = oldInheritancePenalty + maxInheritance
 
   of tyNot:
     considerPreviousT:
@@ -1551,21 +1557,19 @@ 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
+          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
+          # 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