[pulse] Improve trace for Optional Empty Access

Summary: `folly::Optional::value()` returns a reference, hence an error was  shown when the actual value was being accessed. Since `value()` throws an exception in case of `folly::none`, we want to show the error message at the call site of `value()`. We do this by dereferencing the result of  `value()` in the model.

Reviewed By: jvillard

Differential Revision: D24702875

fbshipit-source-id: ca9f30349

infer/src/pulse/PulseModels.ml

@@ -242,7 +242,11 @@ module FollyOptional = struct
   let value optional : model =
    fun _ ~callee_procname:_ location ~ret:(ret_id, _) astate ->
     let event = ValueHistory.Call {f= Model "folly::Optional::value()"; location; in_call= []} in
-    let* astate, (value_addr, value_hist) = to_internal_value_deref location optional astate in
+    let* astate, ((value_addr, value_hist) as value) =
+      to_internal_value_deref location optional astate
+    in
+    (* Check dereference to show an error at the callsite of `value()` *)
+    let* astate, _ = PulseOperations.eval_access location value Dereference astate in
     PulseOperations.write_id ret_id (value_addr, event :: value_hist) astate
     |> PulseOperations.ok_continue
 

infer/tests/codetoanalyze/cpp/pulse/issues.exp

@@ -46,11 +46,12 @@ codetoanalyze/cpp/pulse/nullptr.cpp, deref_nullptr_bad, 2, NULLPTR_DEREFERENCE,
 codetoanalyze/cpp/pulse/nullptr.cpp, no_check_return_bad, 2, NULLPTR_DEREFERENCE, no_bucket, ERROR, [invalidation part of the trace starts here,when calling `may_return_nullptr` here,assigned,is the null pointer,use-after-lifetime part of the trace starts here,passed as argument to `may_return_nullptr`,return from call to `may_return_nullptr`,assigned,invalid access occurs here]
 codetoanalyze/cpp/pulse/nullptr.cpp, std_false_type_deref_bad, 3, NULLPTR_DEREFERENCE, no_bucket, ERROR, [invalidation part of the trace starts here,assigned,is the null pointer,use-after-lifetime part of the trace starts here,assigned,invalid access occurs here]
 codetoanalyze/cpp/pulse/nullptr.cpp, std_true_type_deref_bad, 3, NULLPTR_DEREFERENCE, no_bucket, ERROR, [invalidation part of the trace starts here,assigned,is the null pointer,use-after-lifetime part of the trace starts here,assigned,invalid access occurs here]
-codetoanalyze/cpp/pulse/optional.cpp, assign2_bad, 4, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,when calling `folly::Optional<int>::operator=` here,passed as argument to `folly::Optional::reset()` (modelled),return from call to `folly::Optional::reset()` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional<int>::operator=`,passed as argument to `folly::Optional::reset()` (modelled),return from call to `folly::Optional::reset()` (modelled),return from call to `folly::Optional<int>::operator=`,passed as argument to `folly::Optional::value()` (modelled),return from call to `folly::Optional::value()` (modelled),invalid access occurs here]
-codetoanalyze/cpp/pulse/optional.cpp, assign_bad, 5, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),passed as argument to `folly::Optional<int>::operator=`,parameter `other` of folly::Optional<int>::operator=,passed as argument to `folly::Optional::assign(folly::Optional<Value> arg)` (modelled),return from call to `folly::Optional::assign(folly::Optional<Value> arg)` (modelled),return from call to `folly::Optional<int>::operator=`,passed as argument to `folly::Optional::value()` (modelled),return from call to `folly::Optional::value()` (modelled),invalid access occurs here]
-codetoanalyze/cpp/pulse/optional.cpp, none_copy_bad, 3, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),passed as argument to `folly::Optional::Optional(folly::Optional<Value> arg)` (modelled),return from call to `folly::Optional::Optional(folly::Optional<Value> arg)` (modelled),passed as argument to `folly::Optional::value()` (modelled),return from call to `folly::Optional::value()` (modelled),invalid access occurs here]
-codetoanalyze/cpp/pulse/optional.cpp, none_no_check_bad, 2, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),passed as argument to `folly::Optional::value()` (modelled),return from call to `folly::Optional::value()` (modelled),invalid access occurs here]
+codetoanalyze/cpp/pulse/optional.cpp, assign2_bad, 4, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,when calling `folly::Optional<int>::operator=` here,passed as argument to `folly::Optional::reset()` (modelled),return from call to `folly::Optional::reset()` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional<int>::operator=`,passed as argument to `folly::Optional::reset()` (modelled),return from call to `folly::Optional::reset()` (modelled),return from call to `folly::Optional<int>::operator=`,invalid access occurs here]
+codetoanalyze/cpp/pulse/optional.cpp, assign_bad, 5, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),passed as argument to `folly::Optional<int>::operator=`,parameter `other` of folly::Optional<int>::operator=,passed as argument to `folly::Optional::assign(folly::Optional<Value> arg)` (modelled),return from call to `folly::Optional::assign(folly::Optional<Value> arg)` (modelled),return from call to `folly::Optional<int>::operator=`,invalid access occurs here]
+codetoanalyze/cpp/pulse/optional.cpp, none_copy_bad, 3, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),passed as argument to `folly::Optional::Optional(folly::Optional<Value> arg)` (modelled),return from call to `folly::Optional::Optional(folly::Optional<Value> arg)` (modelled),invalid access occurs here]
+codetoanalyze/cpp/pulse/optional.cpp, none_no_check_bad, 2, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),invalid access occurs here]
 codetoanalyze/cpp/pulse/optional.cpp, operator_arrow_bad, 0, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional::Optional(=None)` (modelled),return from call to `folly::Optional::Optional(=None)` (modelled),when calling `emplace` here,parameter `state` of emplace,passed as argument to `folly::Optional<State>::operator->`,return from call to `folly::Optional<State>::operator->`,invalid access occurs here]
+codetoanalyze/cpp/pulse/optional.cpp, test_trace_ref, 4, OPTIONAL_EMPTY_ACCESS, no_bucket, ERROR, [invalidation part of the trace starts here,when calling `folly::Optional<int>::operator=` here,passed as argument to `folly::Optional::reset()` (modelled),return from call to `folly::Optional::reset()` (modelled),is folly::None,use-after-lifetime part of the trace starts here,passed as argument to `folly::Optional<int>::operator=`,passed as argument to `folly::Optional::reset()` (modelled),return from call to `folly::Optional::reset()` (modelled),return from call to `folly::Optional<int>::operator=`,invalid access occurs here]
 codetoanalyze/cpp/pulse/path.cpp, faulty_call_bad, 0, NULLPTR_DEREFERENCE, no_bucket, ERROR, [calling context starts here,in call to `only_bad_on_42_latent`,invalidation part of the trace starts here,when calling `may_return_null` here,assigned,is the null pointer,use-after-lifetime part of the trace starts here,passed as argument to `may_return_null`,return from call to `may_return_null`,assigned,invalid access occurs here]
 codetoanalyze/cpp/pulse/path.cpp, only_bad_on_42_latent, 2, NULLPTR_DEREFERENCE, no_bucket, ERROR, [*** LATENT ***,invalidation part of the trace starts here,when calling `may_return_null` here,assigned,is the null pointer,use-after-lifetime part of the trace starts here,passed as argument to `may_return_null`,return from call to `may_return_null`,assigned,invalid access occurs here]
 codetoanalyze/cpp/pulse/reference_wrapper.cpp, reference_wrapper_heap_bad, 2, USE_AFTER_DELETE, no_bucket, ERROR, [invalidation part of the trace starts here,when calling `getwrapperHeap` here,passed as argument to `WrapsB::WrapsB`,passed as argument to `new` (modelled),return from call to `new` (modelled),assigned,return from call to `WrapsB::WrapsB`,when calling `WrapsB::~WrapsB` here,parameter `this` of WrapsB::~WrapsB,when calling `WrapsB::__infer_inner_destructor_~WrapsB` here,parameter `this` of WrapsB::__infer_inner_destructor_~WrapsB,was invalidated by `delete`,use-after-lifetime part of the trace starts here,passed as argument to `getwrapperHeap`,passed as argument to `WrapsB::WrapsB`,passed as argument to `new` (modelled),return from call to `new` (modelled),assigned,return from call to `WrapsB::WrapsB`,passed as argument to `ReferenceWrapperHeap::ReferenceWrapperHeap`,parameter `a` of ReferenceWrapperHeap::ReferenceWrapperHeap,passed as argument to `WrapsB::getb`,return from call to `WrapsB::getb`,assigned,return from call to `ReferenceWrapperHeap::ReferenceWrapperHeap`,return from call to `getwrapperHeap`,invalid access occurs here]

infer/tests/codetoanalyze/cpp/pulse/optional.cpp

@@ -159,3 +159,12 @@ int value_or_check_value_ok() {
   }
   return -1;
 }
+
+int test_trace_ref() {
+  folly::Optional<int> foo{5};
+  int sum = foo.value();
+  foo = folly::none;
+  int& x = foo.value();
+  sum += x;
+  return sum;
+}