diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index bec43eca9..e486259e0 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -103,7 +103,7 @@ Error: This variant expression is expected to have type 'a list
 
 - Polymorphic equality is disabled; use type-specific equality instead, even for primitive types
   (e.g., `Int.equal`). However, if your module uses a lot of polymorphic variants with no arguments
-  you may safely `open! PVariant`.
+  you may safely `open PolyVariantEqual`.
 
   If you try and use polymorphic equality `=` in your code you will get a compilation error, such as:
 ```
@@ -117,8 +117,8 @@ Error: This expression has type int but an expression was expected of type
 - Check that your code compiles without warnings with `make -j test_build` (this also runs as part
   of `make test`).
 
-- Apart from `IStd` and `PVariant`, refrain from globally `open`ing modules. Using local open
-  instead when it improves readability: `let open MyModule in ...`.
+- Apart from `IStd` and `PolyVariantEqual`, refrain from globally `open`ing modules. Using
+  local open instead when it improves readability: `let open MyModule in ...`.
 
 - Avoid the use of module aliases, except for the following commonly-aliased modules. Use
   module aliases consistently (e.g., do not alias `L` to a module other than `Logging`).
@@ -156,7 +156,7 @@ Follow `clang-format` (see ".clang-format" at the root of the repository).
 
 ## Testing your Changes
 
-- Make sure infer builds: `make -j `. Refer to the [installation
+- Make sure infer builds: `make -j test_build`. Refer to the [installation
   document](https://github.com/facebook/infer/blob/master/INSTALL.md) for details.
 
 - Run the tests: `make -j 4 test` (adjust 4 to the number of cores available of your machine). The
diff --git a/infer/src/IR/Mleak_buckets.ml b/infer/src/IR/Mleak_buckets.ml
index 1c804e0d2..a7cca0118 100644
--- a/infer/src/IR/Mleak_buckets.ml
+++ b/infer/src/IR/Mleak_buckets.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** This module handles buckets of memory leaks in Objective-C/C++ *)
 
@@ -17,9 +17,9 @@ let bucket_to_message bucket =
   match bucket with `MLeak_cpp -> "[CPP]" | `MLeak_unknown -> "[UNKNOWN ORIGIN]"
 
 
-let contains_cpp = List.mem ~equal:PVariant.( = ) Config.ml_buckets `MLeak_cpp
+let contains_cpp = List.mem ~equal:( = ) Config.ml_buckets `MLeak_cpp
 
-let contains_unknown_origin = List.mem ~equal:PVariant.( = ) Config.ml_buckets `MLeak_unknown
+let contains_unknown_origin = List.mem ~equal:( = ) Config.ml_buckets `MLeak_unknown
 
 let should_raise_leak_unknown_origin = contains_unknown_origin
 
diff --git a/infer/src/IR/Sil.ml b/infer/src/IR/Sil.ml
index d2ed5b6e9..8793548cb 100644
--- a/infer/src/IR/Sil.ml
+++ b/infer/src/IR/Sil.ml
@@ -1164,7 +1164,7 @@ let is_sub_empty = function
 (** Join two substitutions into one.
     For all id in dom(sub1) cap dom(sub2), sub1(id) = sub2(id). *)
 let sub_join sub1 sub2 =
-  let sub = List_.merge_dedup ~compare:compare_ident_exp sub1 sub2 in
+  let sub = IList.merge_dedup ~compare:compare_ident_exp sub1 sub2 in
   assert (sub_no_duplicated_ids sub) ;
   sub
 
diff --git a/infer/src/backend/DifferentialFilters.ml b/infer/src/backend/DifferentialFilters.ml
index 7844d6da7..3b6c432e2 100644
--- a/infer/src/backend/DifferentialFilters.ml
+++ b/infer/src/backend/DifferentialFilters.ml
@@ -236,7 +236,7 @@ let do_filter (diff: Differential.t) (renamings: FileRenamings.t) ~(skip_duplica
     ~(interesting_paths: SourceFile.t list option) : Differential.t =
   let paths_filter = interesting_paths_filter interesting_paths in
   let apply_paths_filter_if_needed label issues =
-    if List.exists ~f:(PVariant.( = ) label) Config.differential_filter_set then
+    if List.exists ~f:(PolyVariantEqual.( = ) label) Config.differential_filter_set then
       paths_filter issues
     else issues
   in
diff --git a/infer/src/backend/StatsAggregator.ml b/infer/src/backend/StatsAggregator.ml
index 70fe1c605..46607b6a1 100644
--- a/infer/src/backend/StatsAggregator.ml
+++ b/infer/src/backend/StatsAggregator.ml
@@ -7,7 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module L = Logging
 
 let aggregated_stats_filename = "aggregated_stats.json"
diff --git a/infer/src/backend/callbacks.ml b/infer/src/backend/callbacks.ml
index 004b82516..2c6730558 100644
--- a/infer/src/backend/callbacks.ml
+++ b/infer/src/backend/callbacks.ml
@@ -8,7 +8,6 @@
  *)
 
 open! IStd
-open! PVariant
 module F = Format
 module L = Logging
 
diff --git a/infer/src/backend/exe_env.ml b/infer/src/backend/exe_env.ml
index df897ba4e..7cea10f16 100644
--- a/infer/src/backend/exe_env.ml
+++ b/infer/src/backend/exe_env.ml
@@ -9,7 +9,6 @@
  *)
 
 open! IStd
-open! PVariant
 module Hashtbl = Caml.Hashtbl
 
 (** Support for Execution environments *)
diff --git a/infer/src/backend/interproc.ml b/infer/src/backend/interproc.ml
index c559bdc69..8d06c90b6 100644
--- a/infer/src/backend/interproc.ml
+++ b/infer/src/backend/interproc.ml
@@ -9,7 +9,6 @@
  *)
 
 open! IStd
-open! PVariant
 module Hashtbl = Caml.Hashtbl
 
 (** Interprocedural Analysis *)
@@ -464,7 +463,8 @@ let forward_tabulate exe_env tenv proc_cfg wl =
       L.d_decrease_indent 1 ;
       L.d_ln ()
     with exn ->
-      reraise_if exn ~f:(fun () -> not !Config.footprint || not (Exceptions.handle_exception exn)) ;
+      IExn.reraise_if exn ~f:(fun () ->
+          not !Config.footprint || not (Exceptions.handle_exception exn) ) ;
       handle_exn exn ;
       L.d_decrease_indent 1 ;
       L.d_ln ()
@@ -494,7 +494,7 @@ let forward_tabulate exe_env tenv proc_cfg wl =
       if !handle_exn_called then Printer.force_delayed_prints () ;
       do_after_node curr_node
     with exn ->
-      reraise_if exn ~f:(fun () -> not (Exceptions.handle_exception exn)) ;
+      IExn.reraise_if exn ~f:(fun () -> not (Exceptions.handle_exception exn)) ;
       handle_exn_node curr_node exn ;
       Printer.force_delayed_prints () ;
       do_after_node curr_node ;
@@ -1202,6 +1202,6 @@ let analyze_procedure {Callbacks.summary; proc_desc; tenv; exe_env} : Specs.summ
   let proc_name = Procdesc.get_proc_name proc_desc in
   Specs.add_summary proc_name summary ;
   ( try ignore (analyze_procedure_aux exe_env tenv proc_desc) with exn ->
-      reraise_if exn ~f:(fun () -> not (Exceptions.handle_exception exn)) ;
+      IExn.reraise_if exn ~f:(fun () -> not (Exceptions.handle_exception exn)) ;
       Reporting.log_error_deprecated proc_name exn ) ;
   Specs.get_summary_unsafe __FILE__ proc_name
diff --git a/infer/src/backend/mergeCapture.ml b/infer/src/backend/mergeCapture.ml
index 7a9e668af..63586bcd7 100644
--- a/infer/src/backend/mergeCapture.ml
+++ b/infer/src/backend/mergeCapture.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module L = Logging
 module F = Format
 
diff --git a/infer/src/backend/ondemand.ml b/infer/src/backend/ondemand.ml
index 31e354c8e..509104a24 100644
--- a/infer/src/backend/ondemand.ml
+++ b/infer/src/backend/ondemand.ml
@@ -8,7 +8,6 @@
  *)
 
 open! IStd
-open! PVariant
 
 (** Module for on-demand analysis. *)
 
@@ -155,7 +154,7 @@ let run_proc_analysis analyze_proc ~caller_pdesc callee_pdesc =
     let final_summary = postprocess summary in
     restore_global_state old_state ; final_summary
   with exn ->
-    reraise_if exn ~f:(fun () -> restore_global_state old_state ; not Config.keep_going) ;
+    IExn.reraise_if exn ~f:(fun () -> restore_global_state old_state ; not Config.keep_going) ;
     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
diff --git a/infer/src/backend/preanal.ml b/infer/src/backend/preanal.ml
index b699af07c..820ca0d18 100644
--- a/infer/src/backend/preanal.ml
+++ b/infer/src/backend/preanal.ml
@@ -9,7 +9,6 @@
  *)
 
 open! IStd
-open! PVariant
 module L = Logging
 
 (** add instructions to perform abstraction *)
diff --git a/infer/src/backend/prover.ml b/infer/src/backend/prover.ml
index 5a2ca6748..b6836c6f2 100644
--- a/infer/src/backend/prover.ml
+++ b/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 ->
-    reraise_after exn ~f:(fun () -> L.d_decrease_indent 1)
+    IExn.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)
diff --git a/infer/src/backend/specs.ml b/infer/src/backend/specs.ml
index dba6afdbf..1bd569203 100644
--- a/infer/src/backend/specs.ml
+++ b/infer/src/backend/specs.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module Hashtbl = Caml.Hashtbl
 
 (** Specifications and spec table *)
diff --git a/infer/src/backend/symExec.ml b/infer/src/backend/symExec.ml
index ed7efc9ae..8b98fc85b 100644
--- a/infer/src/backend/symExec.ml
+++ b/infer/src/backend/symExec.ml
@@ -9,7 +9,6 @@
  *)
 
 open! IStd
-open! PVariant
 
 (** Symbolic Execution *)
 
@@ -1386,7 +1385,7 @@ and instrs ?(mask_errors= false) exe_env tenv pdesc instrs ppl =
     Sil.d_instr instr ;
     L.d_ln () ;
     try sym_exec exe_env tenv pdesc instr p path with exn ->
-      reraise_if exn ~f:(fun () -> not mask_errors || not (SymOp.exn_not_failure exn)) ;
+      IExn.reraise_if exn ~f:(fun () -> not mask_errors || not (SymOp.exn_not_failure exn)) ;
       let error = Exceptions.recognize_exception exn in
       let loc =
         match error.ocaml_pos with
@@ -1598,7 +1597,7 @@ and check_variadic_sentinel ?(fails_on_nil= false) n_formals (sentinel, null_pos
     let tmp_id_deref = Ident.create_fresh Ident.kprimed in
     let load_instr = Sil.Load (tmp_id_deref, lexp, typ, loc) in
     try instrs exe_env tenv pdesc [load_instr] result with e when SymOp.exn_not_failure e ->
-      reraise_if e ~f:(fun () -> fails_on_nil) ;
+      IExn.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 proc_name tenv ~use_buckets:true ~is_premature_nil:true
@@ -1825,7 +1824,8 @@ and sym_exec_wrapper exe_env handle_exn tenv proc_cfg instr ((prop: Prop.normal
     State.mark_instr_ok () ;
     Paths.PathSet.from_renamed_list results
   with exn ->
-    reraise_if exn ~f:(fun () -> not !Config.footprint || not (Exceptions.handle_exception exn)) ;
+    IExn.reraise_if exn ~f:(fun () ->
+        not !Config.footprint || not (Exceptions.handle_exception exn) ) ;
     handle_exn exn ;
     (* calls State.mark_instr_fail *)
     Paths.PathSet.empty
diff --git a/infer/src/base/Config.ml b/infer/src/base/Config.ml
index a5a9cc35c..e7b01e318 100644
--- a/infer/src/base/Config.ml
+++ b/infer/src/base/Config.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** Configuration values: either constant, determined at compile time, or set at startup
     time by system calls, environment variables, or command line options *)
@@ -1167,7 +1167,7 @@ and differential_filter_files =
 
 
 and differential_filter_set =
-  CLOpt.mk_symbol_seq ~long:"differential-filter-set" ~eq:PVariant.( = )
+  CLOpt.mk_symbol_seq ~long:"differential-filter-set" ~eq:PolyVariantEqual.( = )
     "Specify which set of the differential results is filtered with the modified files provided \
      through the $(b,--differential-modified-files) argument. By default it is applied to all \
      sets ($(b,introduced), $(b,fixed), and $(b,preexisting))"
@@ -1372,7 +1372,7 @@ and help =
 and help_format =
   CLOpt.mk_symbol ~long:"help-format"
     ~symbols:[("auto", `Auto); ("groff", `Groff); ("pager", `Pager); ("plain", `Plain)]
-    ~eq:PVariant.( = ) ~default:`Auto
+    ~eq:PolyVariantEqual.( = ) ~default:`Auto
     ~in_help:(List.map InferCommand.all_commands ~f:(fun command -> (command, manual_generic)))
     "Show this help in the specified format. $(b,auto) sets the format to $(b,plain) if the \
      environment variable $(b,TERM) is \"dumb\" or undefined, and to $(b,pager) otherwise."
@@ -1422,7 +1422,7 @@ and issues_fields =
       ; `Issue_field_line_offset
       ; `Issue_field_bug_type
       ; `Issue_field_kind
-      ; `Issue_field_bug_trace ] ~symbols:issues_fields_symbols ~eq:PVariant.( = )
+      ; `Issue_field_bug_trace ] ~symbols:issues_fields_symbols ~eq:PolyVariantEqual.( = )
     "Fields to emit with $(b,--issues-tests)"
 
 
@@ -1556,7 +1556,7 @@ and ml_buckets =
     {|Specify the memory leak buckets to be checked in C++:
 - $(b,cpp) from C++ code
 |}
-    ~symbols:ml_bucket_symbols ~eq:PVariant.( = )
+    ~symbols:ml_bucket_symbols ~eq:PolyVariantEqual.( = )
 
 
 and modified_targets =
@@ -1765,8 +1765,8 @@ and report_formatter =
   CLOpt.mk_symbol ~long:"report-formatter"
     ~in_help:InferCommand.([(Report, manual_generic)])
     ~default:`Phabricator_formatter
-    ~symbols:[("none", `No_formatter); ("phabricator", `Phabricator_formatter)] ~eq:PVariant.( = )
-    "Which formatter to use when emitting the report"
+    ~symbols:[("none", `No_formatter); ("phabricator", `Phabricator_formatter)]
+    ~eq:PolyVariantEqual.( = ) "Which formatter to use when emitting the report"
 
 
 and report_hook =
diff --git a/infer/src/base/DB.ml b/infer/src/base/DB.ml
index 7c85ee96d..fbf028fa9 100644
--- a/infer/src/base/DB.ml
+++ b/infer/src/base/DB.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** Database of analysis results *)
 
diff --git a/infer/src/base/IList.ml b/infer/src/base/IList.ml
index f338c54f4..dbc51f1b0 100644
--- a/infer/src/base/IList.ml
+++ b/infer/src/base/IList.ml
@@ -121,3 +121,19 @@ let append_no_duplicates (type a) ~(cmp: a -> a -> int) =
             if Set.mem set1 x then res_rev else x :: res_rev )
       in
       List.rev res_rev )
+
+
+let merge_dedup l1 l2 ~compare =
+  let rec loop acc l1 l2 =
+    match (l1, l2) with
+    | [], l2 ->
+        List.rev_append acc l2
+    | l1, [] ->
+        List.rev_append acc l1
+    | h1 :: t1, h2 :: t2 ->
+        let cmp = compare h1 h2 in
+        if Int.equal cmp 0 then loop (h1 :: acc) t1 t2
+        else if cmp < 0 then loop (h1 :: acc) t1 l2
+        else loop (h2 :: acc) l1 t2
+  in
+  loop [] l1 l2
diff --git a/infer/src/base/IList.mli b/infer/src/base/IList.mli
index 8a3d609cb..d84ef6c3a 100644
--- a/infer/src/base/IList.mli
+++ b/infer/src/base/IList.mli
@@ -33,3 +33,5 @@ val append_no_duplicates : cmp:('a -> 'a -> int) -> ('a list -> 'a list -> 'a li
 (** [append_no_duplicates list1 list2], assuming that list1 and list2 have no duplicates on their
     own, it computes list1 @ (filtered list2), so it keeps the order of both lists and has no
     duplicates. *)
+
+val merge_dedup : 'a list -> 'a list -> compare:('a -> 'a -> int) -> 'a list
diff --git a/infer/src/base/Logging.ml b/infer/src/base/Logging.ml
index 97cae35be..1f70b48d5 100644
--- a/infer/src/base/Logging.ml
+++ b/infer/src/base/Logging.ml
@@ -308,7 +308,7 @@ let setup_log_file () =
         in
         (* assumes the results dir exists already *)
         let logfile_path = results_dir ^/ Config.log_file in
-        let preexisting_logfile = PVariant.( = ) (Sys.file_exists logfile_path) `Yes in
+        let preexisting_logfile = PolyVariantEqual.( = ) (Sys.file_exists logfile_path) `Yes in
         let chan = Pervasives.open_out_gen [Open_append; Open_creat] 0o666 logfile_path in
         let file_fmt =
           let f = F.formatter_of_out_channel chan in
diff --git a/infer/src/base/Multilinks.ml b/infer/src/base/Multilinks.ml
index 0dad2740f..54e35318a 100644
--- a/infer/src/base/Multilinks.ml
+++ b/infer/src/base/Multilinks.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module F = Format
 module L = Logging
 
diff --git a/infer/src/base/ResultsDatabase.ml b/infer/src/base/ResultsDatabase.ml
index 2f3318ef7..9818ebc32 100644
--- a/infer/src/base/ResultsDatabase.ml
+++ b/infer/src/base/ResultsDatabase.ml
@@ -8,7 +8,6 @@
  *)
 
 open! IStd
-open! PVariant
 module L = Logging
 
 let database : Sqlite3.db option ref = ref None
diff --git a/infer/src/base/ResultsDir.ml b/infer/src/base/ResultsDir.ml
index 9160816ce..2042d95e4 100644
--- a/infer/src/base/ResultsDir.ml
+++ b/infer/src/base/ResultsDir.ml
@@ -7,7 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module CLOpt = CommandLineOption
 module L = Logging
 
diff --git a/infer/src/base/SourceFile.ml b/infer/src/base/SourceFile.ml
index d6d9eeceb..17385e1da 100644
--- a/infer/src/base/SourceFile.ml
+++ b/infer/src/base/SourceFile.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module L = Logging
 
 let count_newlines (path: string) : int =
diff --git a/infer/src/base/SymOp.ml b/infer/src/base/SymOp.ml
index 44dfdcb50..e6ed66b58 100644
--- a/infer/src/base/SymOp.ml
+++ b/infer/src/base/SymOp.ml
@@ -29,10 +29,10 @@ let try_finally ~f ~finally =
   | r ->
       finally () ; r
   | exception (Analysis_failure_exe _ as f_exn) ->
-      reraise_after f_exn ~f:(fun () ->
+      IExn.reraise_after f_exn ~f:(fun () ->
           try finally () with _ -> (* swallow in favor of the original exception *) () )
   | exception f_exn ->
-      reraise_after f_exn ~f:(fun () ->
+      IExn.reraise_after f_exn ~f:(fun () ->
           try finally ()
           with
           | finally_exn
diff --git a/infer/src/base/Utils.ml b/infer/src/base/Utils.ml
index 4f7defdb0..884009212 100644
--- a/infer/src/base/Utils.ml
+++ b/infer/src/base/Utils.ml
@@ -8,7 +8,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module F = Format
 module Hashtbl = Caml.Hashtbl
 module L = Die
@@ -163,7 +163,7 @@ let read_json_file path =
 let do_finally_swallow_timeout ~f ~finally =
   let res =
     try f () with exc ->
-      reraise_after exc ~f:(fun () ->
+      IExn.reraise_after exc ~f:(fun () ->
           try finally () |> ignore with _ -> (* swallow in favor of the original exception *) () )
   in
   let res' = finally () in
@@ -254,7 +254,7 @@ let realpath ?(warn_on_error= true) path =
         Hashtbl.add realpath_cache path (Ok realpath) ;
         realpath
     | exception (Unix.Unix_error (code, _, arg) as exn) ->
-        reraise_after exn ~f:(fun () ->
+        IExn.reraise_after exn ~f:(fun () ->
             if warn_on_error then
               F.eprintf "WARNING: Failed to resolve file %s with \"%s\" @\n@." arg
                 (Unix.Error.message code) ;
diff --git a/infer/src/base/ZipLib.ml b/infer/src/base/ZipLib.ml
index f5a5bee2d..a425f9fca 100644
--- a/infer/src/base/ZipLib.ml
+++ b/infer/src/base/ZipLib.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module L = Logging
 
 type zip_library = {zip_filename: string; zip_channel: Zip.in_file Lazy.t; models: bool}
diff --git a/infer/src/checkers/SiofTrace.ml b/infer/src/checkers/SiofTrace.ml
index 16a4bc4d1..9dbf32c3c 100644
--- a/infer/src/checkers/SiofTrace.ml
+++ b/infer/src/checkers/SiofTrace.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module F = Format
 module L = Logging
 
diff --git a/infer/src/clang/Capture.ml b/infer/src/clang/Capture.ml
index cb0ee0451..7f7e1be42 100644
--- a/infer/src/clang/Capture.ml
+++ b/infer/src/clang/Capture.ml
@@ -103,7 +103,7 @@ let run_clang_frontend ast_source =
 
 let run_and_validate_clang_frontend ast_source =
   try run_clang_frontend ast_source with exc ->
-    reraise_if exc ~f:(fun () -> not Config.keep_going) ;
+    IExn.reraise_if exc ~f:(fun () -> not Config.keep_going) ;
     L.internal_error "ERROR RUNNING CAPTURE: %a@\n%s@\n" Exn.pp exc (Printexc.get_backtrace ())
 
 
diff --git a/infer/src/clang/ComponentKit.ml b/infer/src/clang/ComponentKit.ml
index ecd3d8415..ba516857d 100644
--- a/infer/src/clang/ComponentKit.ml
+++ b/infer/src/clang/ComponentKit.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 module MF = MarkupFormatter
 
 let get_source_range an =
diff --git a/infer/src/clang/cAst_utils.ml b/infer/src/clang/cAst_utils.ml
index c68de1c6f..9ff057bed 100644
--- a/infer/src/clang/cAst_utils.ml
+++ b/infer/src/clang/cAst_utils.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** Functions for transformations of ast nodes *)
 
diff --git a/infer/src/clang/cFrontend_checkers_main.ml b/infer/src/clang/cFrontend_checkers_main.ml
index a99c73bc6..4d5cfbc2d 100644
--- a/infer/src/clang/cFrontend_checkers_main.ml
+++ b/infer/src/clang/cFrontend_checkers_main.ml
@@ -103,7 +103,7 @@ let rec get_responds_to_selector stmt =
     when List.mem ~equal:String.equal responToSelectorMethods mdi.Clang_ast_t.omei_selector ->
       [method_name]
   | BinaryOperator (_, [stmt1; stmt2], _, bo_info)
-    when PVariant.( = ) bo_info.Clang_ast_t.boi_kind `LAnd ->
+    when PolyVariantEqual.( = ) bo_info.Clang_ast_t.boi_kind `LAnd ->
       List.append (get_responds_to_selector stmt1) (get_responds_to_selector stmt2)
   | ImplicitCastExpr (_, [stmt], _, _)
   | ParenExpr (_, [stmt], _)
@@ -146,13 +146,15 @@ let rec get_current_os_version stmt =
   let open Clang_ast_t in
   match stmt with
   | BinaryOperator (_, [stmt1; stmt2], _, bo_info)
-    when PVariant.( = ) bo_info.Clang_ast_t.boi_kind `GE && is_core_foundation_version_number stmt1 ->
+    when PolyVariantEqual.( = ) bo_info.Clang_ast_t.boi_kind `GE
+         && is_core_foundation_version_number stmt1 ->
       Option.to_list (current_os_version_constant stmt2)
   | BinaryOperator (_, [stmt1; stmt2], _, bo_info)
-    when PVariant.( = ) bo_info.Clang_ast_t.boi_kind `LE && is_core_foundation_version_number stmt2 ->
+    when PolyVariantEqual.( = ) bo_info.Clang_ast_t.boi_kind `LE
+         && is_core_foundation_version_number stmt2 ->
       Option.to_list (current_os_version_constant stmt1)
   | BinaryOperator (_, [stmt1; stmt2], _, bo_info)
-    when PVariant.( = ) bo_info.Clang_ast_t.boi_kind `LAnd ->
+    when PolyVariantEqual.( = ) bo_info.Clang_ast_t.boi_kind `LAnd ->
       List.append (get_current_os_version stmt1) (get_current_os_version stmt2)
   | ImplicitCastExpr (_, [stmt], _, _)
   | ParenExpr (_, [stmt], _)
diff --git a/infer/src/clang/cFrontend_decl.ml b/infer/src/clang/cFrontend_decl.ml
index 67a9df64f..de25f604f 100644
--- a/infer/src/clang/cFrontend_decl.ml
+++ b/infer/src/clang/cFrontend_decl.ml
@@ -41,7 +41,7 @@ let protect ~f ~recover ~pp_context (trans_unit_ctx: CFrontend_config.translatio
       log_and_recover ~print:true "Unexpected SelfClassException %a@\n" Typ.Name.pp e.class_name
   | exn ->
       let trace = Backtrace.get () in
-      reraise_if exn ~f:(fun () ->
+      IExn.reraise_if exn ~f:(fun () ->
           L.internal_error "%a: %a@\n%!" pp_context () Exn.pp exn ;
           not Config.keep_going ) ;
       log_and_recover ~print:true "Frontend error: %a@\nBacktrace:@\n%s" Exn.pp exn
diff --git a/infer/src/clang/cLocation.ml b/infer/src/clang/cLocation.ml
index 6b0d9e844..770f6a1d3 100644
--- a/infer/src/clang/cLocation.ml
+++ b/infer/src/clang/cLocation.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** Module for function to retrieve the location (file, line, etc) of instructions *)
 
diff --git a/infer/src/clang/cPredicates.ml b/infer/src/clang/cPredicates.ml
index cb0fd3303..db3157eec 100644
--- a/infer/src/clang/cPredicates.ml
+++ b/infer/src/clang/cPredicates.ml
@@ -247,7 +247,7 @@ let decl_ref_name ?kind name st =
         let has_right_name = ALVar.compare_str_with_alexp ndi.ni_name name in
         match kind with
         | Some decl_kind ->
-            has_right_name && PVariant.( = ) dr.Clang_ast_t.dr_kind decl_kind
+            has_right_name && PolyVariantEqual.( = ) dr.Clang_ast_t.dr_kind decl_kind
         | None ->
             has_right_name )
     | _ ->
@@ -288,7 +288,7 @@ let is_enum_constant_of_enum an name =
         | Some (_, stripped_qual_name) -> (
           match QualifiedCppName.extract_last stripped_qual_name with
           | Some (enum_name, _) ->
-              PVariant.( = ) dr.Clang_ast_t.dr_kind `EnumConstant
+              PolyVariantEqual.( = ) dr.Clang_ast_t.dr_kind `EnumConstant
               && ALVar.compare_str_with_alexp enum_name name
           | _ ->
               false )
@@ -356,7 +356,7 @@ let is_ivar_atomic an =
       match CAst_utils.get_decl ivar_pointer with
       | Some d ->
           let attributes = get_ivar_attributes d in
-          List.exists ~f:(PVariant.( = ) `Atomic) attributes
+          List.exists ~f:(PolyVariantEqual.( = ) `Atomic) attributes
       | _ ->
           false )
   | _ ->
diff --git a/infer/src/clang/cTrans.ml b/infer/src/clang/cTrans.ml
index fb05f852c..ae1d46882 100644
--- a/infer/src/clang/cTrans.ml
+++ b/infer/src/clang/cTrans.ml
@@ -8,7 +8,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** Translates instructions: (statements and expressions) from the ast into sil *)
 
diff --git a/infer/src/clang/cVar_decl.ml b/infer/src/clang/cVar_decl.ml
index 4feec0479..732d4a33c 100644
--- a/infer/src/clang/cVar_decl.ml
+++ b/infer/src/clang/cVar_decl.ml
@@ -8,7 +8,6 @@
  *)
 
 open! IStd
-open! PVariant
 
 (** Process variable declarations by saving them as local or global variables.  *)
 
diff --git a/infer/src/clang/ctl_parser_types.ml b/infer/src/clang/ctl_parser_types.ml
index 823eb25da..26e20f974 100644
--- a/infer/src/clang/ctl_parser_types.ml
+++ b/infer/src/clang/ctl_parser_types.ml
@@ -409,7 +409,7 @@ let builtin_type_kind_assoc =
 
 
 let builtin_equal (bi: Clang_ast_t.builtin_type_kind) (abi: builtin_kind) =
-  match List.Assoc.find ~equal:PVariant.( = ) builtin_type_kind_assoc bi with
+  match List.Assoc.find ~equal:PolyVariantEqual.( = ) builtin_type_kind_assoc bi with
   | Some assoc_abi when equal_builtin_kind assoc_abi abi ->
       true
   | _ ->
diff --git a/infer/src/integration/CaptureCompilationDatabase.ml b/infer/src/integration/CaptureCompilationDatabase.ml
index 769663b2b..3e8db22ab 100644
--- a/infer/src/integration/CaptureCompilationDatabase.ml
+++ b/infer/src/integration/CaptureCompilationDatabase.ml
@@ -30,7 +30,7 @@ let create_cmd (compilation_data: CompilationDatabase.compilation_data) =
    Because infer processes run in parallel but do not share any memory, we use the
    filesystem to signal failures across processes. *)
 let sentinel_exists sentinel_opt =
-  let file_exists sentinel = PVariant.( = ) (Sys.file_exists sentinel) `Yes in
+  let file_exists sentinel = PolyVariantEqual.( = ) (Sys.file_exists sentinel) `Yes in
   Option.value_map ~default:false sentinel_opt ~f:file_exists
 
 
diff --git a/infer/src/integration/Driver.ml b/infer/src/integration/Driver.ml
index 40650e473..d257063a3 100644
--- a/infer/src/integration/Driver.ml
+++ b/infer/src/integration/Driver.ml
@@ -7,7 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 open! IStd
-open! PVariant
+open PolyVariantEqual
 
 (** entry points for top-level functionalities such as capture, analysis, and reporting *)
 
diff --git a/infer/src/integration/Javac.ml b/infer/src/integration/Javac.ml
index e3b46241f..81ef05384 100644
--- a/infer/src/integration/Javac.ml
+++ b/infer/src/integration/Javac.ml
@@ -70,7 +70,7 @@ let compile compiler build_prog build_args =
             (Unix.Exit_or_signal.to_string_hum (Error err))
             shell_cmd log verbose_errlog )
     | exception exn ->
-        reraise_if exn ~f:(fun () ->
+        IExn.reraise_if exn ~f:(fun () ->
             match error_k with
             | Some k ->
                 L.(debug Capture Quiet) "*** Failed: %a!@\n" Exn.pp exn ;
diff --git a/infer/src/istd/.merlin b/infer/src/istd/.merlin
index 61702e145..e47615a55 100644
--- a/infer/src/istd/.merlin
+++ b/infer/src/istd/.merlin
@@ -16,4 +16,5 @@ PKG yojson
 PKG zip
 FLG -principal -safe-string -short-paths -strict-formats -strict-sequence
 FLG -w +a-4-9-40-41-42-44-45-48-60
+FLG -open Core
 S .
diff --git a/infer/src/istd/IExn.ml b/infer/src/istd/IExn.ml
new file mode 100644
index 000000000..41c12e178
--- /dev/null
+++ b/infer/src/istd/IExn.ml
@@ -0,0 +1,20 @@
+(*
+ * Copyright (c) 2018 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+open! Core
+
+let reraise_after ~f exn =
+  let backtrace = Caml.Printexc.get_raw_backtrace () in
+  let () = f () in
+  Caml.Printexc.raise_with_backtrace exn backtrace
+
+
+let reraise_if ~f exn =
+  let backtrace = Caml.Printexc.get_raw_backtrace () in
+  if f () then Caml.Printexc.raise_with_backtrace exn backtrace
diff --git a/infer/src/istd/IExn.mli b/infer/src/istd/IExn.mli
new file mode 100644
index 000000000..269ed296d
--- /dev/null
+++ b/infer/src/istd/IExn.mli
@@ -0,0 +1,18 @@
+(*
+ * Copyright (c) 2018 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+open! Core
+
+val reraise_after : f:(unit -> unit) -> exn -> 'a
+(** Reraise the exception after doing f. Always reraise immediately after catching the exception,
+    otherwise the backtrace can be wrong. *)
+
+val reraise_if : f:(unit -> bool) -> exn -> unit
+(** Reraise the exception if f returns true. Always reraise immediately after catching the
+    exception, otherwise the backtrace can be wrong. *)
diff --git a/infer/src/istd/IStd.ml b/infer/src/istd/IStd.ml
index 86dd22458..a0586e7aa 100644
--- a/infer/src/istd/IStd.ml
+++ b/infer/src/istd/IStd.ml
@@ -1,5 +1,5 @@
 (*
- * Copyright (c) 2016 - present Facebook, Inc.
+ * Copyright (c) 2018 - present Facebook, Inc.
  * All rights reserved.
  *
  * This source code is licensed under the BSD style license found in the
@@ -9,27 +9,6 @@
 
 include Core
 
-module List_ = struct
-  let merge_dedup l1 l2 ~compare =
-    let rec loop acc l1 l2 =
-      match (l1, l2) with
-      | [], l2 ->
-          List.rev_append acc l2
-      | l1, [] ->
-          List.rev_append acc l1
-      | h1 :: t1, h2 :: t2 ->
-          let cmp = compare h1 h2 in
-          if cmp = 0 then loop (h1 :: acc) t1 t2
-          else if cmp < 0 then loop (h1 :: acc) t1 l2
-          else loop (h2 :: acc) l1 t2
-    in
-    loop [] l1 l2
-end
-
-(* Use Caml.Set since they are serialized using Marshal, and Core.Std.Set includes the comparison
-   function in its representation, which Marshal cannot (de)serialize. *)
-module IntSet = Caml.Set.Make (Int)
-
 [@@@warning "-32"]
 
 (* Compare police: generic compare mostly disabled. *)
@@ -47,31 +26,10 @@ let invalid_arg _ : [`use_Logging_die_instead] = assert false
 
 let invalid_argf _ : [`use_Logging_die_instead] = assert false
 
-(** With Logging.exit you have more control of the code that invokes exit, for example when forking
-    and running certain functions that may in turn invoke exit, and you want to handle the execution
-    flow differently - like invoking certain callbacks before exiting, or not exiting at all. *)
 let exit = `In_general_prefer_using_Logging_exit_over_Pervasives_exit
 
 [@@@warning "+32"]
 
-module PVariant = struct
-  (* Equality for polymorphic variants *)
-  let ( = ) (v1: [> ]) (v2: [> ]) = Polymorphic_compare.( = ) v1 v2
-end
-
-(** Reraise the exception after doing f. Always reraise immediately after catching the exception, otherwise the backtrace can be wrong *)
-let reraise_after ~f exn =
-  let backtrace = Caml.Printexc.get_raw_backtrace () 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
-
-
 module ANSITerminal : module type of ANSITerminal = struct
   include ANSITerminal
 
diff --git a/infer/src/istd/IntSet.ml b/infer/src/istd/IntSet.ml
new file mode 100644
index 000000000..61e337fbe
--- /dev/null
+++ b/infer/src/istd/IntSet.ml
@@ -0,0 +1,11 @@
+(*
+ * Copyright (c) 2018 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+open! Core
+include Caml.Set.Make (Int)
diff --git a/infer/src/istd/IntSet.mli b/infer/src/istd/IntSet.mli
new file mode 100644
index 000000000..54fa4419e
--- /dev/null
+++ b/infer/src/istd/IntSet.mli
@@ -0,0 +1,10 @@
+(*
+ * Copyright (c) 2018 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+include Caml.Set.S with type elt = int
diff --git a/infer/src/istd/PolyVariantEqual.ml b/infer/src/istd/PolyVariantEqual.ml
new file mode 100644
index 000000000..0c6bca72d
--- /dev/null
+++ b/infer/src/istd/PolyVariantEqual.ml
@@ -0,0 +1,12 @@
+(*
+ * Copyright (c) 2018 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+open! Core
+
+let ( = ) (v1: [> ]) (v2: [> ]) = Polymorphic_compare.( = ) v1 v2
diff --git a/infer/src/istd/PolyVariantEqual.mli b/infer/src/istd/PolyVariantEqual.mli
new file mode 100644
index 000000000..3eb433bb1
--- /dev/null
+++ b/infer/src/istd/PolyVariantEqual.mli
@@ -0,0 +1,15 @@
+(*
+ * Copyright (c) 2018 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *)
+
+open! Core
+
+(** Open to bring equality [(=)] for polymorphic variants into scope *)
+
+val ( = ) : ([> ] as 'a) -> 'a -> bool
+(** Equality for polymorphic variants *)
diff --git a/infer/src/istd/jbuild.in b/infer/src/istd/jbuild.in
index bae8749fd..a1639a522 100644
--- a/infer/src/istd/jbuild.in
+++ b/infer/src/istd/jbuild.in
@@ -4,7 +4,7 @@
      {|
 (library
  ((name InferStdlib)
-  (flags (%s))
+  (flags (%s -open Core))
   (ocamlopt_flags (%s))
   (libraries (%s))
  ))
diff --git a/infer/src/java/jClasspath.ml b/infer/src/java/jClasspath.ml
index 927b62a88..c9d4f774a 100644
--- a/infer/src/java/jClasspath.ml
+++ b/infer/src/java/jClasspath.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 open Javalib_pack
 module L = Logging
 
diff --git a/infer/src/java/jFrontend.ml b/infer/src/java/jFrontend.ml
index 10108347e..bbf7a1f2f 100644
--- a/infer/src/java/jFrontend.ml
+++ b/infer/src/java/jFrontend.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 open Javalib_pack
 open Sawja_pack
 module L = Logging
diff --git a/infer/src/java/jMain.ml b/infer/src/java/jMain.ml
index b248152f1..b6f5a50ca 100644
--- a/infer/src/java/jMain.ml
+++ b/infer/src/java/jMain.ml
@@ -9,7 +9,7 @@
  *)
 
 open! IStd
-open! PVariant
+open PolyVariantEqual
 open Javalib_pack
 module F = Format
 module L = Logging