From 5b1a05e2826ae222b0cedce740b809ae318af392 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Tue, 14 Apr 2026 19:58:44 +0200
Subject: [PATCH] fixes #18095 (#25744)

---
 compiler/semtypes.nim           |  2 +-
 tests/metatype/deps/cisaorb.nim |  8 ++++++++
 tests/metatype/tcisaorb.nim     | 22 ++++++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 tests/metatype/deps/cisaorb.nim
 create mode 100644 tests/metatype/tcisaorb.nim

diff --git a/compiler/semtypes.nim b/compiler/semtypes.nim
index 46ef4f77f2..0b26cb8b8f 100644
--- a/compiler/semtypes.nim
+++ b/compiler/semtypes.nim
@@ -2380,7 +2380,7 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
     else:
       result = typeExpr.typ.base
       if result.isMetaType and
-         result.kind != tyUserTypeClass:
+         result.kind notin tyTypeClasses:
            # the dot expression may refer to a concept type in
            # a different module. allow a normal alias then.
         let preprocessed = semGenericStmt(c, n)
diff --git a/tests/metatype/deps/cisaorb.nim b/tests/metatype/deps/cisaorb.nim
new file mode 100644
index 0000000000..3cf0a5d523
--- /dev/null
+++ b/tests/metatype/deps/cisaorb.nim
@@ -0,0 +1,8 @@
+type
+  A* = object
+    discard
+
+  B* = object
+    discard
+
+  C* = A | B
diff --git a/tests/metatype/tcisaorb.nim b/tests/metatype/tcisaorb.nim
new file mode 100644
index 0000000000..80d6531aac
--- /dev/null
+++ b/tests/metatype/tcisaorb.nim
@@ -0,0 +1,22 @@
+discard """
+  action: "compile"
+"""
+import deps/cisaorb
+
+when true:
+  # These work fine.
+  discard default(cisaorb.A)
+  proc f1(x: cisaorb.A) = discard
+  discard default(cisaorb.B)
+  proc f2(x: cisaorb.B) = discard
+  discard default(A)
+  proc f3(x: A) = discard
+  discard default(B)
+  proc f4(x: B) = discard
+  proc f5(x: C) = discard
+  proc f6(x: cisaorb.C | C) = discard
+
+proc doesWork(x: A | B) = discard
+
+# Doesn't compile.
+proc f(x: cisaorb.C) = discard