Prepare module header generation for Emacs 28.

* configure.ac: Substitute environment function snippet for Emacs 28.

* src/module-env-28.h: New file, with dummy contents for now.

* src/emacs-module.h.in: Provide emacs_env_28 structure.

Author: phst

configure.ac

@@ -3718,9 +3718,11 @@ AC_CONFIG_FILES([src/emacs-module.h])
 AC_SUBST_FILE([module_env_snippet_25])
 AC_SUBST_FILE([module_env_snippet_26])
 AC_SUBST_FILE([module_env_snippet_27])
+AC_SUBST_FILE([module_env_snippet_28])
 module_env_snippet_25="$srcdir/src/module-env-25.h"
 module_env_snippet_26="$srcdir/src/module-env-26.h"
 module_env_snippet_27="$srcdir/src/module-env-27.h"
+module_env_snippet_28="$srcdir/src/module-env-28.h"
 emacs_major_version="${PACKAGE_VERSION%%.*}"
 AC_SUBST(emacs_major_version)
 

src/emacs-module.h.in

@@ -125,6 +125,17 @@ struct emacs_env_27
 @module_env_snippet_27@
 };
 
+struct emacs_env_28
+{
+@module_env_snippet_25@
+
+@module_env_snippet_26@
+
+@module_env_snippet_27@
+
+@module_env_snippet_28@
+};
+
 /* Every module should define a function as follows.  */
 extern int emacs_module_init (struct emacs_runtime *runtime)
   EMACS_NOEXCEPT

src/module-env-28.h

@@ -0,0 +1,3 @@
+  /* Add module environment functions newly added in Emacs 28 here.
+     Before Emacs 28 is released, remove this comment and start
+     module-env-29.h on the master branch.  */