env refactoring: avoid external uses of {add_import,crc_units}

There is a small change of behavior in this patch due to a different
handling of weak dependencies (those with crco=None); in
Env.check_consistency, only non-weak dependencies would get
[Env.add_import] called, while the `toplevel/` implementations would
also call [Env.add_import] on weak dependencies. After this patch, we
systematically call [add_import] only on non-weak dependencies, even
in `toplevel/`.

([Gabriel:] As far as I can see, the use of [add_import] in the
toplevel never leads to a use of [Env.imports()] for producing
a dependency list, as the toplevel does not produce cmi/cmo files; are
they just no-ops?)

toplevel/topdirs.ml

@@ -118,15 +118,7 @@ let _ = add_directive "cd" (Directive_string dir_cd)
 exception Load_failed
 
 let check_consistency ppf filename cu =
-  try
-    List.iter
-      (fun (name, crco) ->
-       Env.add_import name;
-       match crco with
-         None -> ()
-       | Some crc->
-           Consistbl.check Env.crc_units name crc filename)
-      cu.cu_imports
+  try Env.import_crcs ~source:filename cu.cu_imports
   with Consistbl.Inconsistency(name, user, auth) ->
     fprintf ppf "@[<hv 0>The files %s@ and %s@ \
                  disagree over interface %s@]@."

toplevel/toploop.ml

@@ -492,14 +492,8 @@ let _ =
   Sys.interactive := true;
   let crc_intfs = Symtable.init_toplevel() in
   Compmisc.init_path false;
-  List.iter
-    (fun (name, crco) ->
-      Env.add_import name;
-      match crco with
-        None -> ()
-      | Some crc->
-          Consistbl.set Env.crc_units name crc Sys.executable_name)
-    crc_intfs
+  Env.import_crcs ~source:Sys.executable_name crc_intfs;
+  ()
 
 let load_ocamlinit ppf =
   if !Clflags.noinit then ()

typing/env.ml

@@ -730,16 +730,17 @@ let clear_imports () =
   imported_units := String.Set.empty;
   imported_opaque_units := String.Set.empty
 
+let import_crcs ~source crcs =
+  let import_crc (name, crco) =
+    match crco with
+    | None -> ()
+    | Some crc ->
+        add_import name;
+        Consistbl.check crc_units name crc source
+  in List.iter import_crc crcs
+
 let check_consistency ps =
-  try
-    List.iter
-      (fun (name, crco) ->
-         match crco with
-            None -> ()
-          | Some crc ->
-              add_import name;
-              Consistbl.check crc_units name crc ps.ps_filename)
-      ps.ps_crcs;
+  try import_crcs ~source:ps.ps_filename ps.ps_crcs
   with Consistbl.Inconsistency(name, source, auth) ->
     error (Inconsistent_import(name, auth, source))
 

typing/env.mli

@@ -260,14 +260,12 @@ val crc_of_unit: modname -> Digest.t
 
 val imports: unit -> crcs
 
+(* may raise Consistbl.Inconsistency *)
+val import_crcs: source:string -> crcs -> unit
+
 (* [is_imported_opaque md] returns true if [md] is an opaque imported module  *)
 val is_imported_opaque: string -> bool
 
-(* Direct access to the table of imported compilation units with their CRC *)
-
-val crc_units: Consistbl.t
-val add_import: string -> unit
-
 (* Summaries -- compact representation of an environment, to be
    exported in debugging information. *)