From 1d94d60c7b7d70fcf0de02097d2d8381d2d0a02d Mon Sep 17 00:00:00 2001
From: ringabout <43030857+ringabout@users.noreply.github.com>
Date: Thu, 8 Jan 2026 20:55:10 +0800
Subject: [PATCH] fixes #25419; lift magic types to typeclasses

---
 compiler/semstmts.nim         |  7 +++++++
 tests/types/tissues_types.nim | 10 ++++++++++
 2 files changed, 17 insertions(+)

diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index be9e409108..1cf24c9beb 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -1845,6 +1845,13 @@ proc typeSectionFinalPass(c: PContext, n: PNode) =
           let baseType = s.typ.safeSkipTypes(abstractPtrs)
           if baseType.kind in {tyObject, tyTuple} and not baseType.n.isNil:
             checkForMetaFields(c, baseType.n, hasError)
+
+        if s.typ.kind in {tySet, tyArray, tySequence} 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)
diff --git a/tests/types/tissues_types.nim b/tests/types/tissues_types.nim
index 6bb1258f4d..0421de2125 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