[coqlib] Move `Coqlib` to `library/`.

We move Coqlib to library in preparation for the late binding of
Gallina-level references. Placing `Coqlib` in `library/` is convenient
as some components such as pretyping need to depend on it.

By moving we lose the ability to locate references by syntactic
abbreviations, but IMHO it makes to require ML code to refer to
a true constant instead of an abbreviation/notation.

Unfortunately this change means that we break the `Coqlib`
API (providing a compatibility function is not possible), however we
do so for a good reason.

The main changes are:

- move `Coqlib` to `library/`.
- remove reference -> term from `Coqlib`. In particular, clients will
  have different needs with regards to universes/evar_maps, so we
  force them to call the (not very safe) `Universes.constr_of_global`
  explicitly so the users are marked.
- move late binding of impossible case from `Termops` to
  `pretying/Evarconv`. Remove hook.
- `Coqlib.find_reference` doesn't support syntactic abbreviations
  anymore.
- remove duplication of `Coqlib` code in `Program`.
- remove duplication of `Coqlib` code in `Ltac.Rewrite`.
- A special note about bug 5066 and commit 6e87877 . This case
  illustrates the danger of duplication in the code base; the solution
  chosen there was to transform the not-found anomaly into an error
  message, however the general policy was far from clear. The long
  term solution is indeed make `find_reference` emit `Not_found` and
  let the client handle the error maybe non-fatally. (so they can test
  for constants.

1 files changed, 5 insertions, 4 deletions

diff --git a/vernac/auto_ind_decl.ml b/vernac/auto_ind_decl.ml
index 31d610abd..cf534f13a 100644
--- a/vernac/auto_ind_decl.ml
+++ b/vernac/auto_ind_decl.ml
@@ -62,9 +62,10 @@ let constr_of_global g = lazy (Universes.constr_of_global g)
 (* Some pre declaration of constant we are going to use *)
 let bb = constr_of_global Coqlib.glob_bool
 
-let andb_prop = fun _ -> (Coqlib.build_bool_type()).Coqlib.andb_prop
+let andb_prop = fun _ -> Universes.constr_of_global (Coqlib.build_bool_type()).Coqlib.andb_prop
 
 let andb_true_intro = fun _ ->
+  Universes.constr_of_global
     (Coqlib.build_bool_type()).Coqlib.andb_true_intro
 
 let tt = constr_of_global Coqlib.glob_true
@@ -73,9 +74,9 @@ let ff = constr_of_global Coqlib.glob_false
 
 let eq = constr_of_global Coqlib.glob_eq
 
-let sumbool = Coqlib.build_coq_sumbool
+let sumbool () = Universes.constr_of_global (Coqlib.build_coq_sumbool ())
 
-let andb = fun _ -> (Coqlib.build_bool_type()).Coqlib.andb
+let andb = fun _ -> Universes.constr_of_global (Coqlib.build_bool_type()).Coqlib.andb
 
 let induct_on c = induction false None c None None
 
@@ -849,7 +850,7 @@ let compute_dec_goal ind lnamesparrec nparrec =
         create_input (
           mkNamedProd n (mkFullInd ind (2*nparrec)) (
             mkNamedProd m (mkFullInd ind (2*nparrec+1)) (
-              mkApp(sumbool(),[|eqnm;mkApp (Coqlib.build_coq_not(),[|eqnm|])|])
+              mkApp(sumbool(),[|eqnm;mkApp (Universes.constr_of_global @@ Coqlib.build_coq_not(),[|eqnm|])|])
           )
         )
       )