Fix mapping of intervals in Ast_mapper (#10543)

Co-authored-by: Nicolás Ojeda Bär <n.oje.bar@gmail.com>

Changes

@@ -420,6 +420,10 @@ OCaml 4.13.0
 - #10307: Make build_other_constrs work with names instead of tags.
   (Nicolas Chataing, review by Florian Angeletti)
 
+- #10543: Fix Ast_mapper to apply the mapping function to the constants in
+  "interval" patterns `c1..c2`.
+  (Guillaume Petiot, review by Gabriel Scherer and Nicolás Ojeda Bär)
+
 ### Build system:
 
 - #10289, #10406: Do not print option documentation in usage messages.

parsing/ast_mapper.ml

@@ -484,7 +484,8 @@ module P = struct
     | Ppat_var s -> var ~loc ~attrs (map_loc sub s)
     | Ppat_alias (p, s) -> alias ~loc ~attrs (sub.pat sub p) (map_loc sub s)
     | Ppat_constant c -> constant ~loc ~attrs (sub.constant sub c)
-    | Ppat_interval (c1, c2) -> interval ~loc ~attrs c1 c2
+    | Ppat_interval (c1, c2) ->
+        interval ~loc ~attrs (sub.constant sub c1) (sub.constant sub c2)
     | Ppat_tuple pl -> tuple ~loc ~attrs (List.map (sub.pat sub) pl)
     | Ppat_construct (l, p) ->
         construct ~loc ~attrs (map_loc sub l)