From 7b8145b8bcb0da7f837aebeae53ac3459d774ab9 Mon Sep 17 00:00:00 2001
From: Nikos Gorogiannis <nikosg@fb.com>
Date: Mon, 18 Jan 2021 07:55:55 -0800
Subject: [PATCH] [racerd][C++] do not report on lambdas at top level

Summary:
Lambdas are essentially private (but are not marked as such in Infer),
so we should only report on their non-private callers.

Meanwhile, add a test to document that access propagation to those
callers is currently broken.

Reviewed By: da319

Differential Revision: D25944811

fbshipit-source-id: ef8ca6d9c
---
 infer/src/concurrency/RacerD.ml               |  3 ++
 .../codetoanalyze/cpp/racerd/lambdas.cpp      | 38 +++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 infer/tests/codetoanalyze/cpp/racerd/lambdas.cpp

diff --git a/infer/src/concurrency/RacerD.ml b/infer/src/concurrency/RacerD.ml
index b1f20cf0a..e33447f7e 100644
--- a/infer/src/concurrency/RacerD.ml
+++ b/infer/src/concurrency/RacerD.ml
@@ -683,6 +683,9 @@ let should_report_on_proc tenv procdesc =
       || (not (PredSymb.equal_access (Procdesc.get_access procdesc) Private))
          && (not (Procname.Java.is_autogen_method java_pname))
          && not (Annotations.pdesc_return_annot_ends_with procdesc Annotations.visibleForTesting)
+  | ObjC_Cpp objc_cpp when Procname.ObjC_Cpp.is_cpp_lambda objc_cpp ->
+      (* do not report on lambdas; they are essentially private though do not appear as such *)
+      false
   | ObjC_Cpp {kind= CPPMethod _ | CPPConstructor _ | CPPDestructor _} ->
       not (PredSymb.equal_access (Procdesc.get_access procdesc) Private)
   | ObjC_Cpp {kind= ObjCClassMethod | ObjCInstanceMethod | ObjCInternalMethod; class_name} ->
diff --git a/infer/tests/codetoanalyze/cpp/racerd/lambdas.cpp b/infer/tests/codetoanalyze/cpp/racerd/lambdas.cpp
new file mode 100644
index 000000000..50d37da92
--- /dev/null
+++ b/infer/tests/codetoanalyze/cpp/racerd/lambdas.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <mutex>
+
+class Lambdas {
+ public:
+  void race_in_lambda_even_without_call_ok() {
+    auto lambda_with_sync = [&]() {
+      mutex_.lock();
+      f = 0;
+      mutex_.unlock();
+      return f;
+    };
+  }
+
+  // access propagation to callees does not currently work
+  int FN_race_in_lambda_bad() {
+    auto lambda_with_sync = [&]() { return g; };
+
+    return lambda_with_sync();
+  }
+
+  void set_under_lock(int value) {
+    mutex_.lock();
+    g = value;
+    mutex_.unlock();
+  }
+
+ private:
+  int f;
+  int g;
+  std::mutex mutex_;
+};