2 files changed, 27 insertions, 0 deletions
diff --git a/test-suite/failure/circular_subtyping1.v b/test-suite/failure/circular_subtyping1.v
new file mode 100644
index 000000000..cfd91a2eb
--- /dev/null
+++ b/test-suite/failure/circular_subtyping1.v
@@ -0,0 +1,7 @@
+(* Circular substitution check in subtyping verification *)
+Module Type S. End S.
+Module Type T. Declare Module M:S. End T.
+
+Module N:S. End N.
+Module NN <: T. Module M:=N. End NN.
+Module P <: T with Module M:=NN := NN.
diff --git a/test-suite/failure/circular_subtyping2.v b/test-suite/failure/circular_subtyping2.v
new file mode 100644
index 000000000..75b27bce9
--- /dev/null
+++ b/test-suite/failure/circular_subtyping2.v
@@ -0,0 +1,20 @@
+(* Circular substitution check at functor application *)
+Module Type S. End S.
+Module Type T. Declare Module M:S. End T.
+Module N:S. End N.
+
+Module F (X:S) (Y:T with Module M:=X). End F.
+Module A := F N N.
+
+(* Circular substitution check at with definition *)
+(* Should it be implemented?? *)
+(*
+
+Module NN:T. Module M:=N. End NN.
+Module Type U := T with Module M:=NN.
+(*
+User error: The construction "with Module M:=..." is about to create
+a circular module type. Their resolution is not implemented yet.
+If you really need that feature, please report.
+*)
+*)