Export major version of latest Emacs supported by emacs-module.h.

This is useful if module authors want to support multiple versions of
emacs-module.h.

* configure.ac (emacs_major_version): Define substitution.

* src/emacs-module.h.in (EMACS_MAJOR_VERSION): Define macro.

* doc/lispref/internals.texi (Module Initialization): Document
EMACS_MAJOR_VERSION preprocessor macro.

* test/data/emacs-module/mod-test.c (emacs_module_init): Verify
behavior of EMACS_MAJOR_VERSION.

1 files changed, 5 insertions, 0 deletions

diff --git a/test/data/emacs-module/mod-test.c b/test/data/emacs-module/mod-test.c
index b7007bd80ff..a9154fa167d 100644
--- a/test/data/emacs-module/mod-test.c
+++ b/test/data/emacs-module/mod-test.c
@@ -445,6 +445,11 @@ bind_function (emacs_env *env, const char *name, emacs_value Sfun)
 int
 emacs_module_init (struct emacs_runtime *ert)
 {
+  /* Check that EMACS_MAJOR_VERSION is defined and an integral
+     constant.  */
+  char dummy[EMACS_MAJOR_VERSION];
+  assert (27 <= sizeof dummy);
+
   if (ert->size < sizeof *ert)
     {
       fprintf (stderr, "Runtime size of runtime structure (%"pT" bytes) "