[dead stores] config file for custom scope guard types

Reviewed By: da319

Differential Revision: D6517706

fbshipit-source-id: 3b6f805

infer/src/base/Config.ml

@@ -975,6 +975,12 @@ and cxx_infer_headers =
     "Include C++ header models during compilation. Infer swaps some C++ headers for its own in order to get a better model of, eg, the standard library. This can sometimes cause compilation failures."
 
 
+and cxx_scope_guards =
+  CLOpt.mk_json ~long:"cxx-scope-guards"
+    ~in_help:CLOpt.([(Analyze, manual_clang)])
+    "Specify scope guard classes that can be read only by destructors without being reported as dead stores."
+
+
 and cxx =
   CLOpt.mk_bool ~long:"cxx" ~default:true
     ~in_help:CLOpt.([(Capture, manual_clang)])
@@ -2347,6 +2353,8 @@ and cxx = !cxx
 
 and cxx_infer_headers = !cxx_infer_headers
 
+and cxx_scope_guards = !cxx_scope_guards
+
 and debug_level_analysis = !debug_level_analysis
 
 and debug_level_capture = !debug_level_capture

infer/src/base/Config.mli

@@ -356,6 +356,8 @@ val cxx : bool
 
 val cxx_infer_headers : bool
 
+val cxx_scope_guards : Yojson.Basic.json
+
 val debug_level_analysis : int
 
 val debug_level_capture : int

infer/src/checkers/liveness.ml

@@ -85,27 +85,19 @@ end
 module CFG = ProcCfg.OneInstrPerNode (ProcCfg.Backward (ProcCfg.Exceptional))
 module Analyzer = AbstractInterpreter.Make (CFG) (TransferFunctions)
 
-let checker {Callbacks.tenv; summary; proc_desc} : Specs.summary =
-  let cfg = CFG.from_pdesc proc_desc in
-  let invariant_map =
-    Analyzer.exec_cfg cfg (ProcData.make_default proc_desc tenv) ~initial:Domain.empty ~debug:true
-  in
-  (* we don't want to report in harmless cases like int i = 0; if (...) { i = ... } else { i = ... }
-     that create an intentional dead store as an attempt to imitate default value semantics.
-     use dead stores to a "sentinel" value as a heuristic for ignoring this case *)
-  let is_sentinel_exp = function
-    | Exp.Const Cint i ->
-        IntLit.iszero i || IntLit.isnull i
-    | Exp.Const Cfloat 0.0 ->
-        true
+(* It's fine to have a dead store on a type that uses the "scope guard" pattern. These types
+   are only read in their destructors, and this is expected/ok.
+   (e.g., https://github.com/facebook/folly/blob/master/folly/ScopeGuard.h). *)
+let matcher_scope_guard =
+  let of_json init = function
+    | `List scope_guards ->
+        List.fold scope_guards ~f:(fun acc json -> Yojson.Basic.Util.to_string json :: acc) ~init
     | _ ->
-        false
+        init
   in
-  let matcher_scope_guard =
-    QualifiedCppName.Match.of_fuzzy_qual_names
+  let default_scope_guards =
     [ (* C++ *)
-        "faiss::ScopeDeleter"
-      ; "folly::RWSpinLock::ReadHolder"
+      "folly::RWSpinLock::ReadHolder"
     ; "folly::RWSpinLock::WriteHolder"
     ; "folly::ScopeGuard"
     ; "folly::SharedMutex::ReadHolder"
@@ -120,9 +112,26 @@ let checker {Callbacks.tenv; summary; proc_desc} : Specs.summary =
     ; "std::unique_lock" (* Obj-C *)
     ; "CKComponentScope" ]
   in
-  (* It's fine to have a dead store on a type that uses the "scope guard" pattern. These types
-     are only read in their destructors, and this is expected/ok.
-     (e.g., https://github.com/facebook/folly/blob/master/folly/ScopeGuard.h). *)
+  of_json default_scope_guards Config.cxx_scope_guards
+  |> QualifiedCppName.Match.of_fuzzy_qual_names
+
+
+let checker {Callbacks.tenv; summary; proc_desc} : Specs.summary =
+  let cfg = CFG.from_pdesc proc_desc in
+  let invariant_map =
+    Analyzer.exec_cfg cfg (ProcData.make_default proc_desc tenv) ~initial:Domain.empty ~debug:true
+  in
+  (* we don't want to report in harmless cases like int i = 0; if (...) { i = ... } else { i = ... }
+     that create an intentional dead store as an attempt to imitate default value semantics.
+     use dead stores to a "sentinel" value as a heuristic for ignoring this case *)
+  let is_sentinel_exp = function
+    | Exp.Const Cint i ->
+        IntLit.iszero i || IntLit.isnull i
+    | Exp.Const Cfloat 0.0 ->
+        true
+    | _ ->
+        false
+  in
   let rec is_scope_guard = function
     | {Typ.desc= Tstruct name} ->
         QualifiedCppName.Match.match_qualifiers matcher_scope_guard (Typ.Name.qual_name name)
@@ -169,3 +178,4 @@ let checker {Callbacks.tenv; summary; proc_desc} : Specs.summary =
   in
   List.iter (CFG.nodes cfg) ~f:report_on_node ;
   summary
+

infer/tests/codetoanalyze/cpp/liveness/.inferconfig

@@ -0,0 +1,5 @@
+{
+  "cxx-scope-guards": [
+    "infer::ScopeGuard"
+  ]
+}

infer/tests/codetoanalyze/cpp/liveness/dead_stores.cpp

@@ -11,6 +11,10 @@
 #include <new>
 #include <thread>
 
+namespace infer {
+class ScopeGuard {};
+}; // namespace infer
+
 namespace folly {
 class ScopeGuard {};
 
@@ -301,6 +305,8 @@ void read_holder_ok() { folly::SharedMutex::ReadHolder guard; }
 
 void write_holder_ok() { folly::SharedMutex::WriteHolder guard; }
 
+void custom_scope_guard_ok() { infer::ScopeGuard guard; }
+
 struct S {
   ~S() {}
 };

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

@@ -6,7 +6,7 @@ codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::dead_then_live_bad, 1,
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::easy_bad, 0, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::init_capture_no_call_bad, 1, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::init_capture_reassign_bad, 1, DEAD_STORE, [Write of unused value]
-codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::lambda_bad::lambda_dead_stores.cpp:160:11_operator(), 1, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::lambda_bad::lambda_dead_stores.cpp:164:11_operator(), 1, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus1_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus2_bad, 2, DEAD_STORE, [Write of unused value]
 codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::plus_plus3_bad, 2, DEAD_STORE, [Write of unused value]