[misc] Better preserve backtraces in several modules

Re-raising inside exception handlers must be done with care in order
to preserve backtraces; even if newer OCaml versions do a better job
in automatically spilling `%reraise` in places that matter, there is
no guarantee for that to happen.

I've done a best-effort pass of places that were re-raising
incorrectly, hopefully I got the logic right.

There is the special case of `Nametab.error_global_not_found` which is
raised many times in response to a `Not_found` error; IMHO this error
should be converted to something more specific, however the scope of
that change would be huge as to do easily...

2 files changed, 10 insertions, 5 deletions

diff --git a/lib/cErrors.ml b/lib/cErrors.ml
index 62d465c703..cb64e36755 100644
--- a/lib/cErrors.ml
+++ b/lib/cErrors.ml
@@ -25,12 +25,17 @@ let _ =
   in
   Printexc.register_printer pr
 
-let anomaly ?loc ?label pp =
-  Loc.raise ?loc (Anomaly (label, pp))
+let anomaly ?loc ?info ?label pp =
+  let info = Option.default Exninfo.null info in
+  let info = Option.cata (Loc.add_loc info) info loc in
+  Exninfo.iraise (Anomaly (label, pp), info)
 
 exception UserError of string option * Pp.t (* User errors *)
 
-let user_err ?loc ?hdr strm = Loc.raise ?loc (UserError (hdr, strm))
+let user_err ?loc ?info ?hdr strm =
+  let info = Option.default Exninfo.null info in
+  let info = Option.cata (Loc.add_loc info) info loc in
+  Exninfo.iraise (UserError (hdr, strm), info)
 
 exception Timeout
 
diff --git a/lib/cErrors.mli b/lib/cErrors.mli
index 21d41c996d..cf1857cf04 100644
--- a/lib/cErrors.mli
+++ b/lib/cErrors.mli
@@ -21,7 +21,7 @@ val push : exn -> Exninfo.iexn
  [Anomaly] is used for system errors and [UserError] for the
    user's ones. *)
 
-val anomaly : ?loc:Loc.t -> ?label:string -> Pp.t -> 'a
+val anomaly : ?loc:Loc.t -> ?info:Exninfo.info -> ?label:string -> Pp.t -> 'a
 (** Raise an anomaly, with an optional location and an optional
     label identifying the anomaly. *)
 
@@ -34,7 +34,7 @@ exception UserError of string option * Pp.t
 (** Main error signaling exception. It carries a header plus a pretty printing
     doc *)
 
-val user_err : ?loc:Loc.t -> ?hdr:string -> Pp.t -> 'a
+val user_err : ?loc:Loc.t -> ?info:Exninfo.info -> ?hdr:string -> Pp.t -> 'a
 (** Main error raising primitive. [user_err ?loc ?hdr pp] signals an
     error [pp] with optional header and location [hdr] [loc] *)