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, 6 insertions, 8 deletions

diff --git a/plugins/funind/g_indfun.ml4 b/plugins/funind/g_indfun.ml4
index 893baad8c9..93a89330e3 100644
--- a/plugins/funind/g_indfun.ml4
+++ b/plugins/funind/g_indfun.ml4
@@ -198,15 +198,13 @@ let warning_error names e =
   let (e, _) = Cerrors.process_vernac_interp_error (e, Exninfo.null) in
   match e with
     | Building_graph e ->
-	Feedback.msg_warning
-	  (str "Cannot define graph(s) for " ++
-	     h 1 (pr_enum Libnames.pr_reference names) ++
-	     if do_observe () then (spc () ++ Errors.print e) else mt ())
+       let names = pr_enum Libnames.pr_reference names in
+       let error = if do_observe () then (spc () ++ Errors.print e) else mt () in
+       warn_cannot_define_graph (names,error)
     | Defining_principle e ->
-	Feedback.msg_warning
-	  (str "Cannot define principle(s) for "++
-	     h 1 (pr_enum Libnames.pr_reference names) ++
-	     if do_observe () then Errors.print e else mt ())
+       let names = pr_enum Libnames.pr_reference names in
+       let error = if do_observe () then Errors.print e else mt () in
+       warn_cannot_define_principle (names,error)
     | _ -> raise e