[infer][checkers] add an option to enable the Fragment View Checker

Summary: There was no option to trigger this checker so it was not possible to enable it when not running the default list of checkers

Reviewed By: jberdine

Differential Revision: D5057088

fbshipit-source-id: 7af36f5

infer/src/base/Config.ml

@@ -922,6 +922,10 @@ and flavors =
     "Buck integration using Buck flavors (clang only), eg $(i,`infer --flavors -- buck build \
      //foo:bar#infer`)"
 
+and fragment_retains_view =
+  CLOpt.mk_bool ~long:"fragment-retains-view" ~in_help:CLOpt.[Analyze, manual_generic]
+    "detects when Android fragments are not explicitly nullified before becoming unreabable"
+
 and from_json_report =
   CLOpt.mk_path_opt ~long:"from-json-report"
     ~in_help:CLOpt.[Report, manual_generic]
@@ -1719,6 +1723,7 @@ and filter_paths = !filter_paths
 and filter_report_paths = !filter_report_paths
 and filtering = !filtering
 and flavors = !flavors
+and fragment_retains_view = !fragment_retains_view
 and from_json_report = !from_json_report
 and frontend_debug = !frontend_debug
 and frontend_stats = !frontend_stats

infer/src/base/Config.mli

@@ -235,6 +235,7 @@ val filter_paths : bool
 val filter_report_paths : string option
 val filtering : bool
 val flavors : bool
+val fragment_retains_view : bool
 val from_json_report : string option
 val frontend_debug : bool
 val frontend_tests : bool

infer/src/checkers/registerCheckers.ml

@@ -26,7 +26,8 @@ let active_procedure_checkers () =
   let java_checkers =
     let l =
       [
-        FragmentRetainsViewChecker.callback_fragment_retains_view, enabled_by_default;
+        FragmentRetainsViewChecker.callback_fragment_retains_view, enabled_by_default
+                                                                   || Config.fragment_retains_view;
         Eradicate.callback_eradicate, Config.eradicate;
         BoundedCallTree.checker, Config.crashcontext;
         JavaTaintAnalysis.checker, Config.quandary || enabled_by_default;