preventing Bad_footprint when passing struct value by reference

Reviewed By: jberdine

Differential Revision: D2912475

fb-gh-sync-id: 1dd5442
shipit-source-id: 1dd5442

infer/src/backend/symExec.ml

@@ -1362,7 +1362,7 @@ and call_unknown_or_scan is_scan cfg pdesc tenv pre path
   let actuals_by_ref =
     IList.filter
       (function
-        | Sil.Lvar _, _ -> true
+        | Sil.Lvar _, Sil.Tptr (Sil.Tptr _, _) -> true
         | _ -> false)
       actual_pars in
   let pre_final =

infer/tests/codetoanalyze/c/errors/null_dereference/angelism.c

@@ -35,6 +35,7 @@ extern struct delicious *bakery(struct delicious **cake);
 extern struct delicious *bakery2(struct delicious **cake,
                                  struct delicious **pie);
 extern struct delicious *returnPassByRef();
+extern void skip(struct delicious * s);
 
 struct delicious *skip_external_function(void) {
   struct delicious *cake = NULL;
@@ -87,3 +88,10 @@ void returnPassByRefDeref() {
   ret->yum = 2; // should not report a warning
   free(ret);
 }
+
+int passStructByRefDeref() {
+  struct delicious d;
+  d.yum = 7;
+  skip(&d);
+  return 1 / d.yum; // should not report a warning
+}