[cocci] [PATCH 2/2] Distinguish script-based fresh ids with differing args

[Jan Tojnar <jtojnar@gmail.com>]

https://gitlab.inria.fr/coccinelle/coccinelle/-/commit/f4db03ee748c13d7661e5048c355863466def08b
started memoizing the fresh identifiers generated by scripts to keep them
consistent across different rules. But it did not account for the script
producing a different result depending on the values of inherited
metavariables passed to it as explicit arguments.

Let’s memoize the script results in a hash map,
one fresh name per each different argument list.

Fixes: https://github.com/coccinelle/coccinelle/issues/283

Signed-off-by: Jan Tojnar <jtojnar@gmail.com>
---
 engine/postprocess_transinfo.ml | 67 ++++++++++++++++++---------------
 tests/id4.c                     |  5 +++
 tests/id4.cocci                 | 23 +++++++++++
 tests/id4.res                   |  5 +++
 4 files changed, 70 insertions(+), 30 deletions(-)
 create mode 100644 tests/id4.c
 create mode 100644 tests/id4.cocci
 create mode 100644 tests/id4.res

diff --git a/engine/postprocess_transinfo.ml b/engine/postprocess_transinfo.ml
index 2a00b797..e226fb13 100644
--- a/engine/postprocess_transinfo.ml
+++ b/engine/postprocess_transinfo.ml
@@ -15,6 +15,14 @@ how we reached a particular match *)
 
 module Ast = Ast_cocci
 
+module ParamsType =
+  struct
+    type t = Ast_c.metavars_binding
+    let compare = Stdlib.compare
+  end
+
+module ParamsMap = Map.Make(ParamsType)
+
 let extra_counter = ref 0
 
 let reset_fresh_counter () = extra_counter := 0
@@ -89,38 +97,37 @@ let process_tree inherited_env l =
                    seed in
                string2val(String.concat "" strings))
         | ((r, n) as fresh, Ast.ScriptSeed(name, lang, params, pos, body)) ->
-            let res = ref None in
+            let res = ref ParamsMap.empty in
             let make_fresh_id env =
-              match !res with
+              let args =
+                List.map
+                  (fun (((rule, name) as meta_name), _) ->
+                    try match List.assoc meta_name env with
+                    | Lib_engine.NormalMetaVal v -> (meta_name, v)
+                    | _ ->
+                        failwith
+                          (Printf.sprintf
+                             "Undesired metavar_binding in line %d"
+                             (snd pos))
+                    with
+                    | Not_found ->
+                        let get_meta_names l =
+                          List.map
+                            (fun (mn, _) -> Ast.string_of_meta_name mn)
+                            l in
+                        let string_of_list l =
+                          "[" ^ String.concat "; " l ^ "]" in
+                        failwith
+                          (Printf.sprintf
+                             "%s: script on variable %s cannot be evaluated in line %d. available: %s\nwanted: %s"
+                             r n (snd pos)
+                             (string_of_list (get_meta_names env))
+                             (string_of_list (get_meta_names params)))
+                          )
+                  params in
+              match ParamsMap.find_opt args !res with
                 Some x -> x
               | None ->
-                  let args =
-                    List.map
-                      (fun (((rule, name) as meta_name), _) ->
-                        try match List.assoc meta_name env with
-                        | Lib_engine.NormalMetaVal v -> (meta_name, v)
-                        | _ ->
-                            failwith
-                              (Printf.sprintf
-                                 "Undesired metavar_binding in line %d"
-                                 (snd pos))
-                        with
-                        | Not_found ->
-                            let get_meta_names l =
-                              List.map
-                                (fun (mn, _) -> Ast.string_of_meta_name mn)
-                                l in
-                            let string_of_list l =
-                              "[" ^ String.concat "; " l ^ "]" in
-                            failwith
-                              (Printf.sprintf
-                                 "%s: script on variable %s cannot be evaluated in line %d. available: %s\nwanted: %s"
-                                 r n (snd pos)
-                                 (string_of_list (get_meta_names env))
-                                 (string_of_list (get_meta_names params)))
-                              )
-                      params in
-                  let args = (fresh, Ast_c.MetaIdVal n)::args in
                   let fresh_id =
                     match lang with
                     | "ocaml" ->
@@ -130,7 +137,7 @@ let process_tree inherited_env l =
                         failwith
                           "languages other than ocaml or python not supported" in
                   let r = string2val fresh_id in
-                  res := Some r;
+                  res := ParamsMap.add args r !res;
                   r in
             (fresh, make_fresh_id)
       )
diff --git a/tests/id4.c b/tests/id4.c
new file mode 100644
index 00000000..bb5f99e3
--- /dev/null
+++ b/tests/id4.c
@@ -0,0 +1,5 @@
+void foo() {
+    Foo *widget;
+    widget->window;
+    widget->parent;
+}
diff --git a/tests/id4.cocci b/tests/id4.cocci
new file mode 100644
index 00000000..2619f09e
--- /dev/null
+++ b/tests/id4.cocci
@@ -0,0 +1,23 @@
+@initialize:python@
+@@
+
+def make_prefix_from_type(type_name):
+    # Get just the type name without surrounding whitespace or pointer asterisk.
+    return type_name.strip().strip("*").strip()
+
+def make_getter_name(prefix, member_name):
+    return prefix + "_get_" + member_name
+
+@r1@
+// Getter on declared variables
+type type_name;
+identifier object_var;
+identifier member_name;
+fresh identifier getter_name = script:python(type_name, member_name) { make_getter_name(make_prefix_from_type(type_name), member_name) };
+@@
+
+type_name object_var;
+<...
+-object_var->member_name
++getter_name(object_var)
+...>
diff --git a/tests/id4.res b/tests/id4.res
new file mode 100644
index 00000000..f529a4d6
--- /dev/null
+++ b/tests/id4.res
@@ -0,0 +1,5 @@
+void foo() {
+    Foo *widget;
+    Foo_get_window(widget);
+    Foo_get_parent(widget);
+}
-- 
2.37.2