Add facility to make module functions interactive (Bug#23486).

* src/module-env-28.h: Add field for 'make_interactive' function.

* src/emacs-module.c (Lisp_Module_Function): Add new field holding the
interactive form.
(allocate_module_function): Adapt to structure layout change.
(module_make_interactive, module_function_interactive_form): New
functions.
(initialize_environment): Use them.

* src/eval.c (Fcommandp):
* src/data.c (Finteractive_form): Also handle interactive module
functions.

* test/data/emacs-module/mod-test.c (Fmod_test_identity): New test
function.
(emacs_module_init): Create two interactive module test functions.

* test/src/emacs-module-tests.el (module/interactive/return-t)
(module/interactive/return-t-int, module/interactive/identity):
New unit tests.

* doc/lispref/internals.texi (Module Functions): Document new
function.  Rework paragraph about wrapping module functions, as the
example no longer applies.

* etc/NEWS: Document new facility.

5 files changed, 41 insertions, 2 deletions

diff --git a/src/data.c b/src/data.c
index 59d148166fe..dae8b10ef55 100644
--- a/src/data.c
+++ b/src/data.c
@@ -906,6 +906,13 @@ Value, if non-nil, is a list (interactive SPEC).  */)
       if (PVSIZE (fun) > COMPILED_INTERACTIVE)
         return list2 (Qinteractive, AREF (fun, COMPILED_INTERACTIVE));
     }
+  else if (MODULE_FUNCTIONP (fun))
+    {
+      Lisp_Object form
+        = module_function_interactive_form (XMODULE_FUNCTION (fun));
+      if (! NILP (form))
+        return form;
+    }
   else if (AUTOLOADP (fun))
     return Finteractive_form (Fautoload_do_load (fun, cmd, Qnil));
   else if (CONSP (fun))
diff --git a/src/emacs-module.c b/src/emacs-module.c
index a0bab118019..3581daad112 100644
--- a/src/emacs-module.c
+++ b/src/emacs-module.c
@@ -551,7 +551,7 @@ struct Lisp_Module_Function
   union vectorlike_header header;
 
   /* Fields traced by GC; these must come first.  */
-  Lisp_Object documentation;
+  Lisp_Object documentation, interactive_form;
 
   /* Fields ignored by GC.  */
   ptrdiff_t min_arity, max_arity;
@@ -564,7 +564,7 @@ static struct Lisp_Module_Function *
 allocate_module_function (void)
 {
   return ALLOCATE_PSEUDOVECTOR (struct Lisp_Module_Function,
-                                documentation, PVEC_MODULE_FUNCTION);
+                                interactive_form, PVEC_MODULE_FUNCTION);
 }
 
 #define XSET_MODULE_FUNCTION(var, ptr) \
@@ -630,6 +630,24 @@ module_finalize_function (const struct Lisp_Module_Function *func)
     func->finalizer (func->data);
 }
 
+static void
+module_make_interactive (emacs_env *env, emacs_value function, emacs_value spec)
+{
+  MODULE_FUNCTION_BEGIN ();
+  Lisp_Object lisp_fun = value_to_lisp (function);
+  CHECK_MODULE_FUNCTION (lisp_fun);
+  Lisp_Object lisp_spec = value_to_lisp (spec);
+  /* Normalize (interactive nil) to (interactive). */
+  XMODULE_FUNCTION (lisp_fun)->interactive_form
+    = NILP (lisp_spec) ? list1 (Qinteractive) : list2 (Qinteractive, lisp_spec);
+}
+
+Lisp_Object
+module_function_interactive_form (const struct Lisp_Module_Function *fun)
+{
+  return fun->interactive_form;
+}
+
 static emacs_value
 module_funcall (emacs_env *env, emacs_value func, ptrdiff_t nargs,
                 emacs_value *args)
@@ -1463,6 +1481,7 @@ initialize_environment (emacs_env *env, struct emacs_env_private *priv)
   env->get_function_finalizer = module_get_function_finalizer;
   env->set_function_finalizer = module_set_function_finalizer;
   env->open_channel = module_open_channel;
+  env->make_interactive = module_make_interactive;
   Vmodule_environments = Fcons (make_mint_ptr (env), Vmodule_environments);
   return env;
 }
diff --git a/src/eval.c b/src/eval.c
index 126ee2e9555..fdc3cd1e9f4 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1948,6 +1948,13 @@ then strings and vectors are not accepted.  */)
   else if (COMPILEDP (fun))
     return (PVSIZE (fun) > COMPILED_INTERACTIVE ? Qt : if_prop);
 
+  /* Module functions are interactive if their `interactive_form'
+     field is non-nil. */
+  else if (MODULE_FUNCTIONP (fun))
+    return NILP (module_function_interactive_form (XMODULE_FUNCTION (fun)))
+             ? if_prop
+             : Qt;
+
   /* Strings and vectors are keyboard macros.  */
   if (STRINGP (fun) || VECTORP (fun))
     return (NILP (for_call_interactively) ? Qt : Qnil);
diff --git a/src/lisp.h b/src/lisp.h
index 88e69b9061d..a24898004d4 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -4210,6 +4210,8 @@ extern Lisp_Object funcall_module (Lisp_Object, ptrdiff_t, Lisp_Object *);
 extern Lisp_Object module_function_arity (const struct Lisp_Module_Function *);
 extern Lisp_Object module_function_documentation
   (struct Lisp_Module_Function const *);
+extern Lisp_Object module_function_interactive_form
+  (const struct Lisp_Module_Function *);
 extern module_funcptr module_function_address
   (struct Lisp_Module_Function const *);
 extern void *module_function_data (const struct Lisp_Module_Function *);
diff --git a/src/module-env-28.h b/src/module-env-28.h
index 5d884c148c4..40b03b92b52 100644
--- a/src/module-env-28.h
+++ b/src/module-env-28.h
@@ -12,3 +12,7 @@
 
   int (*open_channel) (emacs_env *env, emacs_value pipe_process)
     EMACS_ATTRIBUTE_NONNULL (1);
+
+  void (*make_interactive) (emacs_env *env, emacs_value function,
+                            emacs_value spec)
+    EMACS_ATTRIBUTE_NONNULL (1);