adds a test case (#24565)

closes #19531

tests/generics/tgeneric0.nim

@@ -194,3 +194,28 @@ block: # bug #21347
   proc b2(n: bool) =        s[K[K[int]]]()
   b1(false)   # Error: 's' has unspecified generic parameters
   b2(false)   # Builds, on its own
+
+block: # bug #19531
+  type
+    Foo[T] = object
+
+    Bar[F: Foo] = object
+      c: proc(t: F.T)
+
+  proc cb[F](v: Bar[F]) =
+    v.c(default(F.T))
+
+  type
+    X = object
+      x: uint32
+    Y = object
+      x: uint32
+  proc cbX(v: X) = discard
+  proc cbY(v: Y) = discard
+
+  let
+    x = Bar[Foo[X]](c: cbX)
+    y = Bar[Foo[Y]](c: cbY)
+  x.cb()
+  y.cb()
+