[Ival] In int_val, fixes [min_max_rem_modu] on singletons.

src/kernel_services/abstract_interp/int_val.ml

@@ -190,16 +190,15 @@ let inject_set_or_top_or_bottom = function
 (* Computes [min], [max], [rem] and [modu] from an integer set. *)
 let make_top_from_set s =
   let min = Int_set.min s in
-  let modu =
-    Int_set.fold
-      (fun x acc ->
-         if Int.equal x min
-         then acc
-         else Int.pgcd (Int.sub x min) acc)
-      s
-      Int.zero
+  let rem, modu =
+    if Int_set.cardinal s = 1
+    then Int.zero, min
+    else
+      let modu =
+        Int_set.fold (fun x acc -> Int.pgcd (Int.sub x min) acc) s Int.zero
+      in
+      Int.e_rem min modu, modu
   in
-  let rem = Int.e_rem min modu in
   let max = Some (Int_set.max s) in
   let min = Some min in
   min, max, rem, modu

src/kernel_services/abstract_interp/int_val.mli

@@ -86,8 +86,7 @@ val max_int: t -> Integer.t option
 val min_and_max: t -> Integer.t option * Integer.t option
 
 (** Returns [min, max, rem, modu] such that for all integers [i] represented by
-    the given abstraction, [i] satisfies min ≤ i ≤ max and i ≅ rem [modu].
-    The abstraction must not be a singleton. *)
+    the given abstraction, [i] satisfies min ≤ i ≤ max and i ≅ rem [modu]. *)
 val min_max_rem_modu:
   t -> Integer.t option * Integer.t option * Integer.t * Integer.t