[log] Even better exception reraising

Summary:
`reraise` was error-prone when one forgot to save the backtrace between where the exception is caught and where it is reraised.
If any exception was raised (even caught) in between, the printed backtrace would be the one of the last exception thrown and it would be very confusing.

This diff kills `reraise` and introduces `reraise_after exn ~f` and `reraise_if exn ~f` to be used right after catching the exception.

Also turned some of them to the common pattern `try_finally ~f ~finally`.

Reviewed By: jvillard

Differential Revision: D5911244

fbshipit-source-id: 9883d1e

infer/src/backend/dom.ml

@@ -1564,10 +1564,11 @@ let sigma_partial_join tenv mode (sigma1: Prop.sigma) (sigma2: Prop.sigma)
   CheckJoin.init mode sigma1 sigma2 ;
   let lost_little = CheckJoin.lost_little in
   let s1, s2, s3 = sigma_partial_join' tenv mode [] sigma1 sigma2 in
-  try
+  Utils.try_finally
-    if Rename.check lost_little then ( CheckJoin.final () ; (s1, s2, s3) )
+    ~f:(fun () ->
-    else ( L.d_strln "failed Rename.check" ; CheckJoin.final () ; raise Sil.JoinFail )
+      if Rename.check lost_little then (s1, s2, s3)
-  with exn -> CheckJoin.final () ; reraise exn
+      else ( L.d_strln "failed Rename.check" ; raise Sil.JoinFail ))
+    ~finally:CheckJoin.final
 
 let rec sigma_partial_meet' tenv (sigma_acc: Prop.sigma) (sigma1_in: Prop.sigma)
     (sigma2_in: Prop.sigma) : Prop.sigma =
@@ -1806,13 +1807,9 @@ let prop_partial_meet tenv p1 p2 =
   FreshVarExp.init () ;
   Todo.init () ;
   try
-    let res = eprop_partial_meet tenv p1 p2 in
+    Utils.try_finally ~f:(fun () -> Some (eprop_partial_meet tenv p1 p2)) ~finally:(fun () ->
-    Rename.final () ; FreshVarExp.final () ; Todo.final () ; Some res
+        Rename.final () ; FreshVarExp.final () ; Todo.final () )
-  with exn ->
+  with Sil.JoinFail -> None
-    Rename.final () ;
-    FreshVarExp.final () ;
-    Todo.final () ;
-    match exn with Sil.JoinFail -> None | _ -> reraise exn
 
 let eprop_partial_join' tenv mode (ep1: Prop.exposed Prop.t) (ep2: Prop.exposed Prop.t)
     : Prop.normal Prop.t =
@@ -1914,21 +1911,15 @@ let prop_partial_join pname tenv mode p1 p2 =
       FreshVarExp.init () ;
       Todo.init () ;
       try
+        Utils.try_finally
+          ~f:(fun () ->
             let p1', p2' = footprint_partial_join' tenv p1 p2 in
             let rename_footprint = Rename.reset () in
             Todo.reset rename_footprint ;
-        let res = Some (eprop_partial_join' tenv mode (Prop.expose p1') (Prop.expose p2')) in
+            let res = eprop_partial_join' tenv mode (Prop.expose p1') (Prop.expose p2') in
             if !Config.footprint then JoinState.set_footprint false ;
-        Rename.final () ;
+            Some res) ~finally:(fun () -> Rename.final () ; FreshVarExp.final () ; Todo.final () )
-        FreshVarExp.final () ;
+      with Sil.JoinFail -> None )
-        Todo.final () ;
-        res
-      with exn ->
-        Rename.final () ;
-        FreshVarExp.final () ;
-        Todo.final () ;
-        if !Config.footprint then JoinState.set_footprint false ;
-        match exn with Sil.JoinFail -> None | _ -> reraise exn )
   | Some _
    -> res_by_implication_only
 
@@ -1937,10 +1928,8 @@ let eprop_partial_join tenv mode (ep1: Prop.exposed Prop.t) (ep2: Prop.exposed P
   Rename.init () ;
   FreshVarExp.init () ;
   Todo.init () ;
-  try
+  Utils.try_finally ~f:(fun () -> eprop_partial_join' tenv mode ep1 ep2) ~finally:(fun () ->
-    let res = eprop_partial_join' tenv mode ep1 ep2 in
+      Rename.final () ; FreshVarExp.final () ; Todo.final () )
-    Rename.final () ; FreshVarExp.final () ; Todo.final () ; res
-  with exn -> Rename.final () ; FreshVarExp.final () ; Todo.final () ; reraise exn
 
 (** {2 Join and Meet for Propset} *)
 

infer/src/backend/interproc.ml

@@ -443,10 +443,10 @@ let forward_tabulate tenv proc_cfg wl =
       L.d_decrease_indent 1 ;
       L.d_ln ()
     with exn ->
-      let backtrace = Caml.Printexc.get_raw_backtrace () in
+      reraise_if exn ~f:(fun () -> not !Config.footprint || not (Exceptions.handle_exception exn)) ;
-      if Exceptions.handle_exception exn && !Config.footprint then (
+      handle_exn exn ;
-        handle_exn exn ; L.d_decrease_indent 1 ; L.d_ln () )
+      L.d_decrease_indent 1 ;
-      else reraise ~backtrace exn
+      L.d_ln ()
   in
   let do_node curr_node pathset_todo session handle_exn =
     check_prop_size pathset_todo ;
@@ -473,13 +473,11 @@ let forward_tabulate tenv proc_cfg wl =
       if !handle_exn_called then Printer.force_delayed_prints () ;
       do_after_node curr_node
     with exn ->
-      let backtrace = Caml.Printexc.get_raw_backtrace () in
+      reraise_if exn ~f:(fun () -> not (Exceptions.handle_exception exn)) ;
-      if Exceptions.handle_exception exn then (
       handle_exn_node curr_node exn ;
       Printer.force_delayed_prints () ;
       do_after_node curr_node ;
-        if not !Config.footprint then raise RE_EXE_ERROR )
+      if not !Config.footprint then raise RE_EXE_ERROR
-      else reraise ~backtrace exn
   in
   while not (Worklist.is_empty wl) do
     let curr_node = Worklist.remove wl in

infer/src/backend/ondemand.ml

@@ -147,8 +147,7 @@ let run_proc_analysis analyze_proc curr_pdesc callee_pdesc =
     let final_summary = postprocess summary in
     restore_global_state old_state ; final_summary
   with exn ->
-    restore_global_state old_state ;
+    reraise_if exn ~f:(fun () -> restore_global_state old_state ; not Config.keep_going) ;
-    if Config.keep_going then (
     L.internal_error "@\nERROR RUNNING BACKEND: %a %s@\n@\nBACK TRACE@\n%s@?" Typ.Procname.pp
       callee_pname (Exn.to_string exn) (Printexc.get_backtrace ()) ;
     match exn with
@@ -158,8 +157,7 @@ let run_proc_analysis analyze_proc curr_pdesc callee_pdesc =
         log_error_and_continue exn initial_summary kind
     | _
      -> (* this happens with assert false or some other unrecognized exception *)
-          log_error_and_continue exn initial_summary (FKcrash (Exn.to_string exn)) )
+        log_error_and_continue exn initial_summary (FKcrash (Exn.to_string exn))
-    else reraise exn
 
 let analyze_proc_desc curr_pdesc callee_pdesc : Specs.summary option =
   let callee_pname = Procdesc.get_proc_name callee_pdesc in

infer/src/backend/prover.ml

@@ -17,7 +17,7 @@ module F = Format
 
 let decrease_indent_when_exception thunk =
   try thunk ()
-  with exn when SymOp.exn_not_failure exn -> L.d_decrease_indent 1 ; reraise exn
+  with exn when SymOp.exn_not_failure exn -> reraise_after exn ~f:(fun () -> L.d_decrease_indent 1)
 
 let compute_max_from_nonempty_int_list l = uw (List.max_elt ~cmp:IntLit.compare_value l)
 

infer/src/backend/symExec.ml

@@ -1401,8 +1401,7 @@ and instrs ?(mask_errors= false) tenv pdesc instrs ppl =
     L.d_ln () ;
     try sym_exec tenv pdesc instr p path
     with exn ->
-      let backtrace = Caml.Printexc.get_raw_backtrace () in
+      reraise_if exn ~f:(fun () -> not mask_errors || not (SymOp.exn_not_failure exn)) ;
-      if SymOp.exn_not_failure exn && mask_errors then
       let error = Exceptions.recognize_exception exn in
       let loc =
         match error.ml_loc with Some ml_loc -> "at " ^ L.ml_loc_to_string ml_loc | None -> ""
@@ -1410,7 +1409,6 @@ and instrs ?(mask_errors= false) tenv pdesc instrs ppl =
       L.d_warning ("Generated Instruction Failed with: " ^ error.name.IssueType.unique_id ^ loc) ;
       L.d_ln () ;
       [(p, path)]
-      else reraise ~backtrace exn
   in
   let f plist instr = List.concat_map ~f:(exe_instr instr) plist in
   List.fold ~f ~init:ppl instrs
@@ -1606,14 +1604,13 @@ and check_variadic_sentinel ?(fails_on_nil= false) n_formals (sentinel, null_pos
     let load_instr = Sil.Load (tmp_id_deref, lexp, typ, loc) in
     try instrs tenv pdesc [load_instr] result
     with e when SymOp.exn_not_failure e ->
-      if not fails_on_nil then
+      reraise_if e ~f:(fun () -> fails_on_nil) ;
       let deref_str = Localise.deref_str_nil_argument_in_variadic_method proc_name nargs i in
       let err_desc =
         Errdesc.explain_dereference tenv ~use_buckets:true ~is_premature_nil:true deref_str prop_
           loc
       in
       raise (Exceptions.Premature_nil_termination (err_desc, __POS__))
-      else reraise e
   in
   (* fold_left reverses the arguments back so that we report an *)
   (* error on the first premature nil argument *)
@@ -1804,11 +1801,10 @@ and sym_exec_wrapper handle_exn tenv proc_cfg instr ((prop: Prop.normal Prop.t),
     State.mark_instr_ok () ;
     Paths.PathSet.from_renamed_list results
   with exn ->
-    let backtrace = Caml.Printexc.get_raw_backtrace () in
+    reraise_if exn ~f:(fun () -> not !Config.footprint || not (Exceptions.handle_exception exn)) ;
-    if Exceptions.handle_exception exn && !Config.footprint then (
+    handle_exn exn ;
-      handle_exn exn ; (* calls State.mark_instr_fail *)
+    (* calls State.mark_instr_fail *)
-                       Paths.PathSet.empty )
+    Paths.PathSet.empty
-    else reraise ~backtrace exn
 
 (** {2 Lifted Abstract Transfer Functions} *)
 

infer/src/backend/timeout.ml

@@ -99,11 +99,11 @@ let exe_timeout f x =
     Option.iter (SymOp.get_timeout_seconds ()) ~f:set_alarm ;
     SymOp.set_alarm ()
   in
-  try suspend_existing_timeout_and_start_new_one () ; f x ; resume_previous_timeout () ; None with
+  try
-  | SymOp.Analysis_failure_exe kind
+    Utils.try_finally
-   -> resume_previous_timeout () ;
+      ~f:(fun () -> suspend_existing_timeout_and_start_new_one () ; f x ; None)
+      ~finally:resume_previous_timeout
+  with SymOp.Analysis_failure_exe kind ->
     L.progressbar_timeout_event kind ;
     Errdesc.warning_err (State.get_loc ()) "TIMEOUT: %a@." SymOp.pp_failure_kind kind ;
     Some kind
-  | exe
-   -> resume_previous_timeout () ; reraise exe

infer/src/base/Config.ml

@@ -2412,11 +2412,11 @@ let specs_library =
 let set_reference_and_call_function reference value f x =
   let saved = !reference in
   let restore () = reference := saved in
-  try
+  Utils.try_finally
+    ~f:(fun () ->
       reference := value ;
-    let res = f x in
+      f x)
-    restore () ; res
+    ~finally:restore
-  with exn -> restore () ; reraise exn
 
 (** Current Objective-C Automatic Reference Counting (ARC) mode *)
 let arc_mode = ref false

infer/src/base/SymOp.ml

@@ -28,22 +28,18 @@ let try_finally ?(fail_early= false) f g =
   | r
    -> g () ; r
   | exception (Analysis_failure_exe _ as f_exn)
-   -> let backtrace = Caml.Printexc.get_raw_backtrace () in
+   -> reraise_after f_exn ~f:(fun () ->
-      ( if not fail_early then
+          if not fail_early then
             try g ()
-          with _ -> () (* swallow in favor of the original exception *) ) ;
+            with _ -> (* swallow in favor of the original exception *) () )
-      reraise ~backtrace f_exn
   | exception f_exn
-   -> let f_backtrace = Caml.Printexc.get_raw_backtrace () in
+   -> reraise_after f_exn ~f:(fun () ->
-      match g () with
+          try g ()
-      | ()
+          with
-       -> reraise ~backtrace:f_backtrace f_exn
+          | g_exn
-      | exception (Analysis_failure_exe _ as g_exn)
+          when (* do not swallow Analysis_failure_exe thrown from g *)
-       -> reraise g_exn
+               match g_exn with Analysis_failure_exe _ -> false | _ -> true
-      | exception _
+          -> () )
-       -> reraise ~backtrace:f_backtrace f_exn
-
-let finally_try g f = try_finally f g
 
 let pp_failure_kind fmt = function
   | FKtimeout

infer/src/base/SymOp.mli

@@ -73,7 +73,4 @@ val try_finally : ?fail_early:bool -> (unit -> 'a) -> (unit -> unit) -> 'a
     return reasonably quickly.  [~fail_early=true] can be passed to skip executing [g ()] when [f
     ()] raises a [Analysis_failure_exe] exception. *)
 
-val finally_try : (unit -> unit) -> (unit -> 'a) -> 'a
-(** [finally_try g f] is equivalent to [try_finally f g]. *)
-
 val pp_failure_kind : Format.formatter -> failure_kind -> unit

infer/src/base/Utils.ml

@@ -165,29 +165,32 @@ let read_json_file path =
   try Ok (Yojson.Basic.from_file path)
   with Sys_error msg | Yojson.Json_error msg -> Error msg
 
-let do_finally f g =
+let do_finally ~f ~finally =
   let res =
     try f ()
     with exc ->
-      let backtrace = Caml.Printexc.get_raw_backtrace () in
+      reraise_after exc ~f:(fun () ->
-      ( try g () |> ignore
+          try finally () |> ignore
-        with _ -> () (* swallow in favor of the original exception *) ) ;
+          with _ -> (* swallow in favor of the original exception *) () )
-      reraise ~backtrace exc
   in
-  let res' = g () in
+  let res' = finally () in
   (res, res')
 
+let try_finally ~f ~finally =
+  let res, () = do_finally ~f ~finally in
+  res
+
 let with_file_in file ~f =
   let ic = In_channel.create file in
   let f () = f ic in
-  let g () = In_channel.close ic in
+  let finally () = In_channel.close ic in
-  do_finally f g |> fst
+  try_finally ~f ~finally
 
 let with_file_out file ~f =
   let oc = Out_channel.create file in
   let f () = f oc in
-  let g () = Out_channel.close oc in
+  let finally () = Out_channel.close oc in
-  do_finally f g |> fst
+  try_finally ~f ~finally
 
 let write_json_to_file destfile json =
   with_file_out destfile ~f:(fun oc -> Yojson.Basic.pretty_to_channel oc json)
@@ -199,8 +202,8 @@ let consume_in chan_in =
 let with_process_in command read =
   let chan = Unix.open_process_in command in
   let f () = read chan in
-  let g () = consume_in chan ; Unix.close_process_in chan in
+  let finally () = consume_in chan ; Unix.close_process_in chan in
-  do_finally f g
+  do_finally ~f ~finally
 
 let shell_escape_command cmd =
   let escape arg =

infer/src/base/Utils.mli

@@ -94,3 +94,6 @@ val write_file_with_locking : ?delete:bool -> f:(Out_channel.t -> unit) -> strin
 
 val rmtree : string -> unit
 (** [rmtree path] removes [path] and, if [path] is a directory, recursively removes its contents *)
+
+val try_finally : f:(unit -> 'a) -> finally:(unit -> unit) -> 'a
+(** Calls [f] then [finally] even if [f] raised an exception. The original exception is reraised afterwards. *)

infer/src/clang/Capture.ml

@@ -93,8 +93,7 @@ let run_clang_frontend ast_source =
 let run_and_validate_clang_frontend ast_source =
   try run_clang_frontend ast_source
   with exc ->
-    if not Config.keep_going then reraise exc
+    reraise_if exc ~f:(fun () -> not Config.keep_going) ;
-    else
     L.internal_error "ERROR RUNNING CAPTURE: %a@\n%s@\n" Exn.pp exc (Printexc.get_backtrace ())
 
 let run_clang clang_command read =

infer/src/integration/Javac.ml

@@ -59,27 +59,25 @@ let compile compiler build_prog build_args =
     let shell_cmd = Utils.shell_escape_command cmd in
     let shell_cmd_redirected = Printf.sprintf "%s 2>'%s'" shell_cmd verbose_out_file in
     L.(debug Capture Quiet) "Trying to execute: %s@." shell_cmd_redirected ;
-    let error_k_or_fail err_msg =
+    match Utils.with_process_in shell_cmd_redirected In_channel.input_all with
-      match (error_k, err_msg) with
+    | log, Error err -> (
-      | Some k, `UnixError (err, log)
+      match error_k with
+      | Some k
        -> L.(debug Capture Quiet)
             "*** Failed: %s!@\n%s@." (Unix.Exit_or_signal.to_string_hum (Error err)) log ;
           k ()
-      | Some k, `ExceptionError exn
+      | None
-       -> L.(debug Capture Quiet) "*** Failed: %a!@\n" Exn.pp exn ; k ()
-      | None, `UnixError (err, log)
        -> let verbose_errlog = Utils.with_file_in verbose_out_file ~f:In_channel.input_all in
           L.(die UserError)
             "@\n*** Failed to execute compilation command: %s@\n*** Command: %s@\n*** Output:@\n%s%s@\n*** Infer needs a working compilation command to run.@."
-            (Unix.Exit_or_signal.to_string_hum (Error err)) shell_cmd log verbose_errlog
+            (Unix.Exit_or_signal.to_string_hum (Error err)) shell_cmd log verbose_errlog )
-      | None, `ExceptionError exn
-       -> reraise exn
-    in
-    match Utils.with_process_in shell_cmd_redirected In_channel.input_all with
-    | log, Error err
-     -> error_k_or_fail (`UnixError (err, log))
     | exception exn
-     -> error_k_or_fail (`ExceptionError exn)
+     -> reraise_if exn ~f:(fun () ->
+            match error_k with
+            | Some k
+             -> L.(debug Capture Quiet) "*** Failed: %a!@\n" Exn.pp exn ; k () ; false
+            | None
+             -> true )
     | log, Ok ()
      -> L.(debug Capture Quiet) "*** Success. Logs:@\n%s" log
   in

infer/src/istd/IStd.ml

@@ -63,12 +63,17 @@ module PVariant = struct
   let ( = ) (v1: [> ]) (v2: [> ]) = Polymorphic_compare.( = ) v1 v2
 end
 
-let reraise ?backtrace:backtrace0 exn =
+(** Reraise the exception after doing f. Always reraise immediately after catching the exception, otherwise the backtrace can be wrong *)
-  let backtrace =
+let reraise_after ~f exn =
-    match backtrace0 with Some bt -> bt | None -> Caml.Printexc.get_raw_backtrace ()
+  let backtrace = Caml.Printexc.get_raw_backtrace () in
-  in
+  let () = f () in
   Caml.Printexc.raise_with_backtrace exn backtrace
 
+(** Reraise the exception if f returns true. Always reraise immediately after catching the exception, otherwise the backtrace can be wrong *)
+let reraise_if ~f exn =
+  let backtrace = Caml.Printexc.get_raw_backtrace () in
+  if f () then Caml.Printexc.raise_with_backtrace exn backtrace
+
 let failwith _ : [`use_Logging_die_instead] = assert false
 
 let failwithf _ : [`use_Logging_die_instead] = assert false

infer/src/java/jFrontend.ml

@@ -202,7 +202,9 @@ let compute_source_icfg linereader classes program tenv source_basename package_
     {JContext.cg= Cg.create source_file; JContext.cfg= Cfg.create_cfg (); JContext.tenv= tenv}
   in
   let select test procedure cn node =
-    if test node then try procedure cn node with Bir.Subroutine -> () | e -> reraise e
+    if test node then
+      try procedure cn node
+      with Bir.Subroutine -> ()
   in
   let () =
     JBasics.ClassMap.iter
@@ -216,9 +218,6 @@ let compute_class_icfg source_file linereader program tenv node =
   let icfg =
     {JContext.cg= Cg.create source_file; JContext.cfg= Cfg.create_cfg (); JContext.tenv= tenv}
   in
-  ( try create_icfg source_file linereader program icfg (Javalib.get_name node) node with
+  ( try create_icfg source_file linereader program icfg (Javalib.get_name node) node
-  | Bir.Subroutine
+    with Bir.Subroutine -> () ) ;
-   -> ()
-  | e
-   -> reraise e ) ;
   (icfg.JContext.cg, icfg.JContext.cfg)