[buck] create log files erase at the end of the run

Summary: This way, if infer crashes then the log files will be available for inspection, but if it succeeds we still get rid of the (non-deterministic) logs before Buck caches the results.

Reviewed By: sblackshear

Differential Revision: D5416032

fbshipit-source-id: 22e58be

infer/src/base/Logging.ml

@@ -287,12 +287,6 @@ let setup_log_file () =
       ()
   | _, `Buffer b
    -> let fmt, chan, preexisting_logfile =
-        if Config.buck_cache_mode then
-          (* suppress log file in order not to cause flakiness in the Buck cache *)
-          let devnull_chan = Out_channel.create "/dev/null" in
-          let devnull_fmt = F.formatter_of_out_channel devnull_chan in
-          (devnull_fmt, devnull_chan, true)
-        else
         (* assumes Config.results_dir exists already *)
         let logfile_path = Config.results_dir ^/ Config.log_file in
         let preexisting_logfile = PVariant.( = ) (Sys.file_exists logfile_path) `Yes in

infer/src/integration/Driver.ml

@@ -143,13 +143,15 @@ let clean_results_dir () =
     List.mem ~equal:String.equal dirs_to_delete
   in
   let should_delete_file =
+    let files_to_delete = [Config.log_file] in
     let suffixes_to_delete =
       ".txt" :: ".csv" :: ".json" :: (if Config.flavors then [] else [".cfg"; ".cg"])
     in
     fun name ->
       (* Keep the JSON report *)
       not (String.equal (Filename.basename name) Config.report_json)
-      && List.exists ~f:(Filename.check_suffix name) suffixes_to_delete
+      && ( List.mem ~equal:String.equal files_to_delete (Filename.basename name)
+         || List.exists ~f:(Filename.check_suffix name) suffixes_to_delete )
   in
   let rec clean name =
     let rec cleandir dir =