Make checking for liveness of global values more precise.

We can't just use a hash lookup because a global and a local reference
might refer to the same Lisp object.

* src/emacs-module.c (module_free_global_ref): More precise check for
global liveness.

* test/data/emacs-module/mod-test.c (Fmod_test_globref_invalid_free):
New test module function.
(emacs_module_init): Export it.

* test/src/emacs-module-tests.el
(module--test-assertions--globref-invalid-free): New unit test.

1 files changed, 14 insertions, 0 deletions

diff --git a/test/data/emacs-module/mod-test.c b/test/data/emacs-module/mod-test.c
index 437faaee2a0..ed289d7a863 100644
--- a/test/data/emacs-module/mod-test.c
+++ b/test/data/emacs-module/mod-test.c
@@ -201,7 +201,19 @@ Fmod_test_globref_free (emacs_env *env, ptrdiff_t nargs, emacs_value args[],
   return env->intern (env, "ok");
 }
 
+/* Treat a local reference as global and free it.  Module assertions
+   should detect this case even if a global reference representing the
+   same object also exists.  */
 
+static emacs_value
+Fmod_test_globref_invalid_free (emacs_env *env, ptrdiff_t nargs,
+                                emacs_value *args, void *data)
+{
+  emacs_value local = env->make_integer (env, 9876);
+  env->make_global_ref (env, local);
+  env->free_global_ref (env, local);  /* Not allowed. */
+  return env->intern (env, "nil");
+}
 
 /* Return a copy of the argument string where every 'a' is replaced
    with 'b'.  */
@@ -694,6 +706,8 @@ emacs_module_init (struct emacs_runtime *ert)
 	 1, 1, NULL, NULL);
   DEFUN ("mod-test-globref-make", Fmod_test_globref_make, 0, 0, NULL, NULL);
   DEFUN ("mod-test-globref-free", Fmod_test_globref_free, 4, 4, NULL, NULL);
+  DEFUN ("mod-test-globref-invalid-free", Fmod_test_globref_invalid_free, 0, 0,
+         NULL, NULL);
   DEFUN ("mod-test-string-a-to-b", Fmod_test_string_a_to_b, 1, 1, NULL, NULL);
   DEFUN ("mod-test-userptr-make", Fmod_test_userptr_make, 1, 1, NULL, NULL);
   DEFUN ("mod-test-userptr-get", Fmod_test_userptr_get, 1, 1, NULL, NULL);