make get_decl_from_typ_ptr return optional type instead of crashing

Summary:
public
Make Ast_utils.get_decl_from_typ_ptr function more forgiving.
It will return None instead of crashing when there is no decl for a given type.
This is done in prepratation to try to get destructor function of any type without crashing.

Reviewed By: dulmarod

Differential Revision: D2769302

fb-gh-sync-id: 7a9fcfe

infer/src/clang/cFrontend_utils.ml

@@ -350,13 +350,10 @@ struct
   let get_decl_from_typ_ptr typ_ptr =
     let typ_opt = get_desugared_type typ_ptr in
     let typ = match typ_opt with Some t -> t | _ -> assert false in
-    let get_decl_or_fail decl_ptr = match get_decl decl_ptr with
-      | Some d -> d
-      | None -> assert false in
     (* it needs extending to handle objC types *)
     match typ with
-    | Clang_ast_t.RecordType (ti, decl_ptr) -> get_decl_or_fail decl_ptr
+    | Clang_ast_t.RecordType (ti, decl_ptr) -> get_decl decl_ptr
-    | _ -> assert false
+    | _ -> None
 
   (*TODO take the attributes into account too. To be done after we get the attribute's arguments. *)
   let is_type_nonnull type_ptr =

infer/src/clang/cFrontend_utils.mli

@@ -103,7 +103,7 @@ sig
 
   (** returns declaration of the type for certain types and crashes for others
       NOTE: this function needs extending to handle objC types *)
-  val get_decl_from_typ_ptr : Clang_ast_t.type_ptr -> Clang_ast_t.decl
+  val get_decl_from_typ_ptr : Clang_ast_t.type_ptr -> Clang_ast_t.decl option
 
   val string_of_type_ptr : Clang_ast_t.type_ptr -> string
 

infer/src/clang/cTypes_decl.ml

@@ -133,7 +133,10 @@ let get_superclass_decls decl =
   | ClassTemplateSpecializationDecl (_, _, _, _, _, _, _, cxx_rec_info) ->
       (* there is no concept of virtual inheritance in the backend right now *)
       let base_ptr = cxx_rec_info.Clang_ast_t.xrdi_bases @ cxx_rec_info.Clang_ast_t.xrdi_vbases in
-      IList.map Ast_utils.get_decl_from_typ_ptr base_ptr
+      let get_decl_or_fail typ_ptr = match Ast_utils.get_decl_from_typ_ptr typ_ptr with
+        | Some decl -> decl
+        | None -> assert false in
+      IList.map get_decl_or_fail base_ptr
   | _ -> []
 
 (** fetches list of superclasses for C++ classes *)