Add test of princiaplity from polymorphic type constraints

stedolan · Dec 16, 2022 · 4b68bb3 · 4b68bb3
1 parent 82c7afe
commit 4b68bb3
Showing 1 changed file with 18 additions and 0 deletions.
diff --git a/testsuite/tests/typing-poly/pr11544.ml b/testsuite/tests/typing-poly/pr11544.ml
@@ -0,0 +1,18 @@
+(* TEST
+   * expect
+*)
+
+module M = struct type t = T end
+let poly3 : 'b. M.t -> 'b -> 'b =
+  fun T x -> x
+[%%expect {|
+module M : sig type t = T end
+val poly3 : M.t -> 'b -> 'b = <fun>
+|}, Principal{|
+module M : sig type t = T end
+Line 3, characters 6-7:
+3 |   fun T x -> x
+          ^
+Warning 18 [not-principal]: this type-based constructor disambiguation is not principal.
+val poly3 : M.t -> 'b -> 'b = <fun>
+|}];;