Unbreak build when building without GMP support.

Add support for a new preprocessor macro EMACS_MODULE_HAVE_MPZ_T to
emacs-module.h.  If this macro is defined, assume that mpz_t is
already defined and don’t include gmp.h.

Don’t document the new macro for now, as it’s unclear whether we want
to support this in modules outside the Emacs tree.

* src/emacs-module.h.in: Allow user to prevent inclusion of gmp.h.

* src/emacs-module.c: Use mini-gmp if GMP is unavailable.  Don’t
include gmp.h.

* src/lisp.h: Don’t require gmp.h.  It’s not needed for lisp.h.

* test/Makefile.in (GMP_LIB, GMP_OBJ): New variables.
($(test_module)): Use them.

* test/data/emacs-module/mod-test.c: Use mini-gmp if GMP is unavailable.

2 files changed, 6 insertions, 3 deletions

diff --git a/src/emacs-module.c b/src/emacs-module.c
index b6a12386267..0b7b3d6ffbe 100644
--- a/src/emacs-module.c
+++ b/src/emacs-module.c
@@ -70,6 +70,11 @@ To add a new module function, proceed as follows:
 
 #include <config.h>
 
+#ifndef HAVE_GMP
+#include "mini-gmp.h"
+#define EMACS_MODULE_HAVE_MPZ_T
+#endif
+
 #define EMACS_MODULE_GMP
 #include "emacs-module.h"
 
@@ -80,8 +85,6 @@ To add a new module function, proceed as follows:
 #include <stdlib.h>
 #include <time.h>
 
-#include <gmp.h>
-
 #include "lisp.h"
 #include "bignum.h"
 #include "dynlib.h"
diff --git a/src/emacs-module.h.in b/src/emacs-module.h.in
index e61aadfc3ac..fbc62a61ef4 100644
--- a/src/emacs-module.h.in
+++ b/src/emacs-module.h.in
@@ -28,7 +28,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <stdbool.h>
 #endif
 
-#ifdef EMACS_MODULE_GMP
+#if defined EMACS_MODULE_GMP && !defined EMACS_MODULE_HAVE_MPZ_T
 #include <gmp.h>
 #endif