A new infrastructure for warnings.

On the user side, coqtop and coqc take a list of warning names or categories
after -w. No prefix means activate the warning, a "-" prefix means deactivate
it, and "+" means turn the warning into an error. Special categories include
"all", and "default" which contains the warnings enabled by default.

We also provide a vernacular Set Warnings which takes the same flags as argument.

Note that coqc now prints warnings.

The name and category of a warning are printed with the warning itself.

On the developer side, Feedback.msg_warning is still accessible, but the
recommended way to print a warning is in two steps:

1) create it by:

let warn_my_warning =
  CWarnings.create ~name:"my-warning" ~category:"my-category"
    (fun args -> Pp.strbrk ...)

2) print it by:

warn_my_warning args

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/cWarnings.mli b/lib/cWarnings.mli
new file mode 100644
index 000000000..351554284
--- /dev/null
+++ b/lib/cWarnings.mli
@@ -0,0 +1,34 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+type status =
+  Disabled | Enabled | AsError
+
+(*
+type 'a repr = {
+  print : 'a -> Pp.std_ppcmds;
+  kind : string;
+  enabled : bool;
+}
+ *)
+
+val set_current_loc : Loc.t -> unit
+
+val create : name:string -> category:string -> ?default:status ->
+             ('a -> Pp.std_ppcmds) -> ?loc:Loc.t -> 'a -> unit
+
+(*
+val emit : 'a t -> 'a -> unit
+
+type any = Any : string * string * 'a repr -> any
+
+val dump : unit -> any list
+ *)
+
+val get_flags : unit -> string
+val set_flags : string -> unit