Add a reproduction case for issue #173. Discovered by @Lozov-Petr

Signed-off-by: Dmitrii.Kosarev a.k.a. Kakadu <[email protected]>

regression_ppx/dune

@@ -148,13 +148,29 @@
  (modules test013mutual)
  (package OCanren)
  (public_names -)
- (flags
-  (:standard
-   ;-dsource
-   ;
-   ))
  (preprocess
-  (pps OCanren-ppx.ppx_distrib GT.ppx_all -- -new-typenames -pretty))
+  (pps
+   OCanren-ppx.ppx_distrib
+   GT.ppx_all
+   OCanren-ppx.ppx_fresh
+   --
+   -new-typenames
+   -pretty))
+ (libraries OCanren OCanren.tester))
+
+(executables
+ (names test014diseq)
+ (modules test014diseq)
+ (package OCanren)
+ (public_names -)
+ (preprocess
+  (pps
+   GT.ppx_all
+   OCanren-ppx.ppx_fresh
+   OCanren-ppx.ppx_tester
+   OCanren-ppx.ppx_repr
+   --
+   -pretty))
  (libraries OCanren OCanren.tester))
 
 (cram
@@ -283,3 +299,12 @@
   %{project_root}/ppx/pp_ocanren_all.exe
   test013mutual.ml
   test013mutual.exe))
+
+(cram
+ (package OCanren)
+ (applies_to test014)
+ (deps
+  (package OCanren-ppx)
+  %{project_root}/ppx/pp_ocanren_all.exe
+  test014diseq.ml
+  test014diseq.exe))

regression_ppx/test014.t

@@ -0,0 +1,4 @@
+  $ ./test014diseq.exe
+  rel, 1 answer {
+  Fatal error: exception File "src/core/Disequality.ml", line 177, characters 8-14: Assertion failed
+  [2]

regression_ppx/test014diseq.ml

@@ -0,0 +1,18 @@
+open OCanren
+open Tester
+
+let rel list1 =
+  let open OCanren.Std in
+  fresh
+    (list2 hd1 tl1 hd2 tl2)
+    (list1 =/= list2)
+    (list1 === hd1 % tl1)
+    (list2 === hd2 % tl2)
+    (hd2 === !!1)
+    (tl2 === nil ())
+    (hd1 === !!1)
+    (tl1 === nil ())
+;;
+
+(* let () = [%tester run_r [%show GT.int GT.list] (Std.List.reify reify) 1 (fun q -> rel q)] *)
+let () = run_r (Std.List.reify reify) ([%show: GT.int logic Std.List.logic] ()) 1 q qh (REPR rel)