Use Gnulib libgmp module

Instead of doing GMP by hand, use the Gnulib libgmp module.
* .gitignore: Add lib/gmp.h.
* admin/merge-gnulib (GNULIB_MODULES): Add libgmp.
* configure.ac (GMP_LIB, GMP_OBJ): Remove.  Gnulib uses the name
LIB_GMP, so all uses changed.  All uses of GMP_OBJ removed.
(HAVE_GMP): Set this from Gnulib’s variables.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.
* lib/mini-gmp-gnulib.c, lib/mini-gmp.c, lib/mini-gmp.h, m4/libgmp.m4:
New files, copied from Gnulib.
* src/bignum.h, test/data/emacs-module/mod-test.c:
Include gmp.h unconditionally.
* src/mini-gmp-emacs.c, src/mini-gmp.c, src/mini-gmp.h:
Remove.  This moves these files from src to lib, and
updates them to the current GMP version.
* test/Makefile.in (GMP_H): New macro.
($(test_module)): Use it to decide whether to compile
mini-gmp-gnulib.c too.

2 files changed, 53 insertions, 0 deletions

diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 3a0fae11c44..f577a6fa741 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -118,6 +118,7 @@ AC_DEFUN([gl_EARLY],
   AC_REQUIRE([AC_SYS_LARGEFILE])
   # Code from module lchmod:
   # Code from module libc-config:
+  # Code from module libgmp:
   # Code from module limits-h:
   # Code from module localtime-buffer:
   # Code from module lstat:
@@ -345,6 +346,10 @@ AC_DEFUN([gl_INIT],
   gl_INTTYPES_INCOMPLETE
   AC_REQUIRE([gl_LARGEFILE])
   gl___INLINE
+  gl_LIBGMP
+  if test -n "$GMP_H"; then
+    AC_LIBOBJ([mini-gmp-gnulib])
+  fi
   gl_LIMITS_H
   gl_FUNC_LSTAT
   if test $REPLACE_LSTAT = 1; then
@@ -1035,6 +1040,9 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/memmem.c
   lib/mempcpy.c
   lib/memrchr.c
+  lib/mini-gmp-gnulib.c
+  lib/mini-gmp.c
+  lib/mini-gmp.h
   lib/minmax.h
   lib/mkostemp.c
   lib/mktime-internal.h
@@ -1166,6 +1174,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/inttypes.m4
   m4/largefile.m4
   m4/lchmod.m4
+  m4/libgmp.m4
   m4/limits-h.m4
   m4/localtime-buffer.m4
   m4/lstat.m4
diff --git a/m4/libgmp.m4 b/m4/libgmp.m4
new file mode 100644
index 00000000000..b569bb73462
--- /dev/null
+++ b/m4/libgmp.m4
@@ -0,0 +1,44 @@
+# Configure the GMP library or a replacement.
+
+dnl Copyright 2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_LIBGMP],
+[
+  AC_ARG_WITH([libgmp],
+    [AS_HELP_STRING([--without-libgmp],
+       [do not use the GNU Multiple Precision (GMP) library;
+        this is the default on systems lacking libgmp.])])
+
+  AC_CHECK_HEADERS_ONCE([gmp.h])
+  GMP_H=gmp.h
+  LIB_GMP=
+
+  case $with_libgmp in
+    no) ;;
+    yes) GMP_H= LIB_GMP=-lgmp;;
+    *) if test "$ac_cv_header_gmp_h" = yes; then
+         gl_saved_LIBS=$LIBS
+         AC_SEARCH_LIBS([__gmpz_roinit_n], [gmp])
+         LIBS=$gl_saved_LIBS
+         case $ac_cv_search___gmpz_roinit_n in
+           'none needed')
+             GMP_H=;;
+           -*)
+             GMP_H= LIB_GMP=$ac_cv_search___gmpz_roinit_n;;
+         esac
+       fi;;
+  esac
+
+  if test -z "$GMP_H"; then
+    AC_DEFINE([HAVE_GMP], 1,
+      [Define to 1 if you have the GMP library instead of just the
+       mini-gmp replacement.])
+  fi
+
+  AC_SUBST([LIB_GMP])
+  AC_SUBST([GMP_H])
+  AM_CONDITIONAL([GL_GENERATE_GMP_H], [test -n "$GMP_H"])
+])