From 97c160271ca9e36ec382323735a7cfdaf45de124 Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Wed, 14 Jan 2026 23:25:52 +0800
Subject: [PATCH] fixes #25419; lift magic types to typeclasses (#25421)

fixes #25419

(cherry picked from commit 40480fe3481cf833ed927f83a177d43046e7c37d)
---
 compiler/semstmts.nim         | 11 +++++++++--
 tests/types/tissues_types.nim | 10 ++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 3146d8efbc..f91a6c83d3 100644
--- a/compiler/semstmts.nim
+++ b/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):
diff --git a/tests/types/tissues_types.nim b/tests/types/tissues_types.nim
index 6bb1258f4d..d5eb60be42 100644
--- a/tests/types/tissues_types.nim
+++ b/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