[inferbo] Suppress exception on placement new

Summary:
It avoids raising an exception when unexpected arguments are given to
placement new.  We will revert this after fixing the frontend to parse
user defined `new` correctly in the future.

Reviewed By: mbouaziz

Differential Revision: D10378136

fbshipit-source-id: d494f781b

infer/src/bufferoverrun/bufferOverrunModels.ml

@@ -186,7 +186,10 @@ let placement_new size_exp (src_exp1, t1) src_arg2_opt =
             | Some (src_exp2, t2) when Typ.is_pointer_to_void t2 ->
                 src_exp2
             | _ ->
-                L.(die InternalError) "Unexpected types of arguments for __placement_new"
+                (* TODO: Raise an exception when given unexpected arguments.  Before that, we need
+                   to fix the frontend to parse user defined `new` correctly. *)
+                L.(debug BufferOverrun Verbose) "Unexpected types of arguments for __placement_new" ;
+                src_exp1
         in
         let v = Sem.eval src_exp mem in
         Dom.Mem.add_stack (Loc.of_id id) v mem

infer/tests/codetoanalyze/cpp/bufferoverrun/class.cpp

@@ -131,6 +131,20 @@ void placement_new_overload4_Good() {
   x->a[0] = 0;
 }
 
+struct Allocator {
+  void* allocate(std::size_t size) { return malloc(size); }
+};
+
+void* operator new(std::size_t size, Allocator& allocator) {
+  return allocator.allocate(size);
+}
+
+void user_defined_new_Bad_FN() {
+  Allocator allocator;
+  my_class2* x = new (allocator) my_class2();
+  x->a[10] = 0;
+}
+
 class my_class4 {
  public:
   int a[3];