fix compilation regression in alea

tests/concepts/tconceptinclosure.nim

@@ -0,0 +1,33 @@
+discard """
+  output: "10\n20"
+"""
+
+type
+  FonConcept = concept x
+    x.x is int
+
+  Implementation = object
+    x: int
+
+  Closure = object
+    f: proc()
+
+proc f1(x: FonConcept): Closure =
+  result.f = proc () =
+    echo x.x
+
+proc f2(x: FonConcept): Closure =
+  result.f = proc () =
+    echo x.x
+
+let x = Implementation(x: 10)
+let y = Implementation(x: 20)
+
+let a = x.f1
+let b = x.f2
+let c = x.f1
+let d = y.f2
+
+a.f()
+d.f()
+