[dead stores] recognize lambdas with `auto` parameter

Summary:
When a lambda has an `auto` parameter, the inferred type of the parameter because part of the name.
Our heuristic for identifying lambda was checking if the lambda's name was exactly `operator()`, which won't catch this case.

Reviewed By: jvillard

Differential Revision: D5753323

fbshipit-source-id: 85ff75a

infer/src/checkers/liveness.ml

@@ -66,7 +66,7 @@ let checker {Callbacks.tenv; summary; proc_desc} : Specs.summary =
   in
   let procname = Procdesc.get_proc_name proc_desc in
   let is_cpp_lambda =
-    match Typ.Procname.get_method procname with "operator()" -> true | _ -> false
+    String.is_substring ~substring:"operator()" (Typ.Procname.get_method procname)
   in
   let is_captured_var pvar =
     let pvar_name = Pvar.get_name pvar in

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

@@ -122,6 +122,12 @@ void by_ref1_ok(int& ref) { ref = 7; }
 
 void by_ref2_ok(int& ref) { ref++; }
 
+int capture_by_ref3_ok() {
+  int x = 0;
+  [&](auto y) { x += y; }(3);
+  return x;
+}
+
 int plus_plus_ok() {
   int x = 0;
   return ++x;

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

@@ -4,7 +4,7 @@ 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:139:11_operator(), 1, DEAD_STORE, [Write of unused value]
+codetoanalyze/cpp/liveness/dead_stores.cpp, dead_stores::lambda_bad::lambda_dead_stores.cpp:145:11_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]