fixes #25419; lift magic types to typeclasses (#25421)

fixes #25419

(cherry picked from commit 40480fe348)

compiler/semstmts.nim

@@ -617,7 +617,7 @@ proc checkDefineType(c: PContext; v: PSym; t: PType) =
     # no distinct types for generic define
     skipped.excl tyDistinct
   if t.skipTypes(skipped).kind notin typeKinds:
-    let name = 
+    let name =
       case v.magic
       of mStrDefine: "strdefine"
       of mIntDefine: "intdefine"
@@ -1829,6 +1829,13 @@ proc typeSectionFinalPass(c: PContext, n: PNode) =
            x[0].kind in {nkObjectTy, nkTupleTy})
           ):
           checkForMetaFields(c, baseType.n, hasError)
+
+        if s.typ.kind in {tySet, tyArray, tySequence, tyUncheckedArray} and s.typ.elementType.kind == tyNone:
+          # magic generics are not filled but tyNone is added to its elements by default,
+          # we lift them to tyBuiltInTypeClass here
+          s.typ = newTypeS(tyBuiltInTypeClass, c,
+                    newTypeS(s.typ.kind, c))
+
         if not hasError:
           checkConstructedType(c.config, s.info, s.typ)
   #instAllTypeBoundOp(c, n.info)
@@ -2640,7 +2647,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
           # we need to add a result symbol for them
           maybeAddResult(c, s, n)
 
- 
+
         trackProc(c, s, s.ast[bodyPos])
       else:
         if (s.typ.returnType != nil and s.kind != skIterator):

tests/types/tissues_types.nim

@@ -116,3 +116,13 @@ block:
   s(something)
   s(otherthing, something)
   s(something, otherthing)
+
+block:
+  type
+    Test = set
+    Test2 = seq
+    Test3 = array
+
+  doAssert set is Test
+  doAssert seq is Test2
+  doAssert array is Test3