Fix conversion to pointer arithmetic

clangml-transforms/for_memcad.ml

@@ -596,10 +596,17 @@ with type 'a Applicative.t = 'a Applicative.t = struct
       { record_decl with fields = name_anonymous_fields record_decl.fields },
     Free_monoid.zero
 
-  let is_pointer_type (ty : Clang.Type.t) =
-    match ty.desc with
-    | Pointer _ -> true
-    | _ -> false
+  let is_array (expr : Clang.Expr.t) =
+    let cursor = Clang.Ast.cursor_of_node expr in
+    match Clang.ext_get_cursor_kind cursor with
+    | ImplicitCastExpr ->
+        let child = Option.get (Clang.first_child cursor) in
+        begin match Clang.get_type_kind (Clang.get_cursor_type child) with
+        | ConstantArray -> true
+        | _ -> false
+        end
+    | _ ->
+        false
 
   let hook :
     type a . a Refl.refl -> (a -> env -> a * accu) -> (a -> env -> a * accu) =
@@ -632,7 +639,7 @@ with type 'a Applicative.t = 'a Applicative.t = struct
         | UnaryExpr { kind = SizeOf; argument } ->
             visit_unary_expr_size_of argument env
         | ArraySubscript { base; index }
-             when is_pointer_type (Clang.Type.of_node base) ->
+            when not (is_array base) ->
             let x' : Clang.Ast.expr_desc = UnaryOperator {
               kind = Deref;
               operand = { base with desc = BinaryOperator {