Inclusion of functors with restricted signature is now forbidden (fix #3746)

 The previous behavior was to include the interface of such a functor,
 possibly leading to the creation of unexpected axioms, see bug report #3746.
 In the case of non-functor module with restricted signature, we could
 simply refer to the original objects (strengthening), but for a functor,
 the inner objects have no existence yet. As said in the new error message,
 a simple workaround is hence to first instantiate the functor, then include
 the local instance:

  Module LocalInstance := Funct(Args).
  Include LocalInstance.

 By the way, the mod_type_alg field is now filled more systematically,
 cf new comments in declarations.mli. This way, we could use it to know
 whether a module had been given a restricted signature (via ":"). Earlier,
 some mod_type_alg were None in situations not handled by the extraction
 (MEapply of module type).

 Some code refactoring on the fly.

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/modops.mli b/kernel/modops.mli
index a335ad9b4..86aae598c 100644
--- a/kernel/modops.mli
+++ b/kernel/modops.mli
@@ -126,13 +126,12 @@ type module_typing_error =
   | IncorrectWithConstraint of Label.t
   | GenerativeModuleExpected of Label.t
   | LabelMissing of Label.t * string
+  | IncludeRestrictedFunctor of module_path
 
 exception ModuleTypingError of module_typing_error
 
 val error_existing_label : Label.t -> 'a
 
-val error_application_to_not_path : module_struct_entry -> 'a
-
 val error_incompatible_modtypes :
   module_type_body -> module_type_body -> 'a
 
@@ -152,3 +151,5 @@ val error_incorrect_with_constraint : Label.t -> 'a
 val error_generative_module_expected : Label.t -> 'a
 
 val error_no_such_label_sub : Label.t->string->'a
+
+val error_include_restricted_functor : module_path -> 'a