Fix #5888

tests/concepts/t5888.nim

@@ -0,0 +1,26 @@
+discard """
+output: '''
+true
+true
+true
+f
+0
+'''
+"""
+
+import t5888lib/ca, t5888lib/opt
+
+type LocalCA = ca.CA
+
+proc f(c: CA) =
+  echo "f"
+  echo c.x
+
+var o = new(Opt)
+
+echo o is CA
+echo o is LocalCA
+echo o is ca.CA
+
+o.f()
+

tests/concepts/t5888lib/ca.nim

@@ -0,0 +1,4 @@
+type
+  CA* = concept c
+    c.x is int
+

tests/concepts/t5888lib/opt.nim

@@ -0,0 +1,6 @@
+import ca
+
+type
+  Opt* = object
+    x*: int
+