Make mini-gmp safe for --enable-gcc-warnings

* configure.ac (GMP_OBJ): When building mini-gmp, compile
mini-gmp-emacs.c, not mini-gmp.c.
* lib-src/etags.c (NDEBUG): Don't attempt to redefine, in
case the builder compiles with -DNDEBUG.
* src/conf_post.h (NDEBUG) [!ENABLE_CHECKING && !NDEBUG]: Define.
This avoids bloat in mini-gmp-emacs.o.
* src/mini-gmp-emacs.c: New file, which pacifies --enable-gcc-warnings.

2 files changed, 41 insertions, 2 deletions

diff --git a/src/conf_post.h b/src/conf_post.h
index 0927fca7ca3..f9838bc662a 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -20,9 +20,16 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 /* Put the code here rather than in configure.ac using AH_BOTTOM.
    This way, the code does not get processed by autoheader.  For
-   example, undefs here are not commented out.
+   example, undefs here are not commented out.  */
 
-   To help make dependencies clearer elsewhere, this file typically
+/* Disable 'assert' unless enabling checking.  Do this early, in
+   case some misguided implementation depends on NDEBUG in some
+   include file other than assert.h.  */
+#if !defined ENABLE_CHECKING && !defined NDEBUG
+# define NDEBUG
+#endif
+
+/* To help make dependencies clearer elsewhere, this file typically
    does not #include other files.  The exceptions are first stdbool.h
    because it is unlikely to interfere with configuration and bool is
    such a core part of the C language, and second ms-w32.h (DOS_NT
diff --git a/src/mini-gmp-emacs.c b/src/mini-gmp-emacs.c
new file mode 100644
index 00000000000..7a1b7ab5de5
--- /dev/null
+++ b/src/mini-gmp-emacs.c
@@ -0,0 +1,32 @@
+/* Tailor mini-gmp.c for GNU Emacs
+
+Copyright 2018 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or (at
+your option) any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include <stddef.h>
+
+/* Pacify GCC -Wsuggest-attribute=malloc.  */
+static void *gmp_default_alloc (size_t) ATTRIBUTE_MALLOC;
+
+/* Pacify GCC -Wunused-variable for variables used only in 'assert' calls.  */
+#if defined NDEBUG && GNUC_PREREQ (4, 6, 0)
+# pragma GCC diagnostic ignored "-Wunused-variable"
+#endif
+
+#include "mini-gmp.c"