fixes #2346

tests/concepts/tusertypeclasses.nim

@@ -0,0 +1,68 @@
+discard """
+  output: '''Sortable
+Sortable
+Container
+true
+true
+false
+false
+false
+'''
+"""
+
+import typetraits
+
+type
+  TObj = object
+    x: int
+
+  Sortable = generic x, y
+    (x < y) is bool
+
+  ObjectContainer = generic C
+    C.len is Ordinal
+    for v in items(C):
+      v.type is tuple|object
+
+proc foo(c: ObjectContainer) =
+  echo "Container"
+
+proc foo(x: Sortable) =
+  echo "Sortable"
+
+foo 10
+foo "test"
+foo(@[TObj(x: 10), TObj(x: 20)])
+
+proc intval(x: int): int = 10
+
+# check real and virtual fields
+type
+  TFoo = generic T
+    T.x
+    y(T)
+    intval T.y
+    let z = intval(T.y)
+
+proc y(x: TObj): int = 10
+
+proc testFoo(x: TFoo) = discard
+testFoo(TObj(x: 10))
+
+type
+  Matrix[Rows, Cols: static[int]; T] = generic M
+    M.M == Rows
+    M.N == Cols
+    M.T is T
+
+  MyMatrix[M, N: static[int]; T] = object
+    data: array[M*N, T]
+
+var x: MyMatrix[3, 3, int]
+
+echo x is Matrix
+echo x is Matrix[3, 3, int]
+echo x is Matrix[3, 3, float]
+echo x is Matrix[4, 3, int]
+echo x is Matrix[3, 4, int]
+