[frontend][c++] Translate pointer-to-member expressions

Summary:
This diff translates C++ pointer-to-member expressions [5.5] to
pointer arithmetic.

Reviewed By: mbouaziz

Differential Revision: D6132554

fbshipit-source-id: 9b77a4c

infer/src/IR/HilInstr.ml

@@ -87,9 +87,11 @@ let of_sil ~include_array_indexes ~f_resolve_id (instr: Sil.instr) =
                 ap
             | [] ->
                 L.(die InternalError)
-                  "Invalid pointer arithmetic expression %a used as LHS" Exp.pp lhs_exp )
+                  "Invalid pointer arithmetic expression %a used as LHS at %a" Exp.pp lhs_exp
+                  Location.pp_file_pos loc )
         | _ ->
-            L.(die InternalError) "Non-assignable LHS expression %a" Exp.pp lhs_exp
+            L.(die InternalError)
+              "Non-assignable LHS expression %a at %a" Exp.pp lhs_exp Location.pp_file_pos loc
       in
       Instr (Assign (lhs_access_path, exp_of_sil rhs_exp typ, loc))
   | Call (ret_opt, call_exp, formals, loc, call_flags) ->

infer/src/clang/cArithmetic_trans.ml

@@ -64,6 +64,16 @@ let compound_assignment_binary_operation_instruction boi e1 typ e2 loc =
 let binary_operation_instruction boi e1 typ e2 loc =
   let binop_exp op = Exp.BinOp (op, e1, e2) in
   match boi.Clang_ast_t.boi_kind with
+  (* Note: Pointers to members that are not statically known are not
+     expressible in Sil. The translation of the PtrMem ops treats the field as
+     an integer offset, which is itself semantically ok though too low-level,
+     but the translation of the argument expressions does not compute such
+     offsets and instead passes the member pointer at type 'void'. *)
+  | `PtrMemD ->
+      (binop_exp Binop.PlusPI, [])
+  | `PtrMemI ->
+      let id = Ident.create_fresh Ident.knormal in
+      (Exp.BinOp (PlusPI, Exp.Var id, e2), [Sil.Load (id, e1, typ, loc)])
   | `Add ->
       (binop_exp Binop.PlusA, [])
   | `Mul ->
@@ -115,13 +125,6 @@ let binary_operation_instruction boi e1 typ e2 loc =
   | `XorAssign
   | `OrAssign ->
       compound_assignment_binary_operation_instruction boi e1 typ e2 loc
-  (* We should not get here.  *)
-  (* These should be treated by compound_assignment_binary_operation_instruction*)
-  | bok ->
-      L.(debug Capture Medium)
-        "@\nWARNING: Missing translation for Binary Operator Kind %s. Construct ignored...@\n"
-        (Clang_ast_j.string_of_binary_operator_kind bok) ;
-      (Exp.minus_one, [])
 
 
 let unary_operation_instruction translation_unit_context uoi e typ loc =

infer/tests/codetoanalyze/cpp/shared/reference/ptr_mem.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2017 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+struct item {
+  int data;
+  item* next;
+};
+
+template <typename E>
+struct List {
+  List(E* E::*next_ptr) : head(nullptr), next_ptr(next_ptr) {}
+
+  void add(E* e) {
+    e->*next_ptr = head;
+    head = e;
+  }
+
+  void add_byref(E& e) {
+    e.*next_ptr = head;
+    head = &e;
+  }
+
+  E* head;
+  E* E::*next_ptr;
+};
+
+int main() {
+  List<item> l(&item::next);
+
+  item i;
+  l.add(&i);
+  l.add_byref(i);
+}