Improve --enable-gcc-warnings for MinGW64

This partially reverts my 2016-05-30 patch.  Apparently MinGW64
still requires pacifications that GCC 7.1.1 x86-64 (Fedora 26)
does not.  Also, pacify tparam.c, which isn’t used on Fedora.
* lib-src/etags.c (process_file_name, TeX_commands):
* src/buffer.c (fix_overlays_before):
* src/data.c (Fmake_variable_buffer_local, cons_to_unsigned)
(cons_to_signed):
* src/editfns.c (Ftranslate_region_internal):
Prefer UNINIT to some stray value, as this simplifies
code-reading later.
* src/eval.c (CACHEABLE): New macro.
(internal_lisp_condition_case): Use it.
* src/tparam.c (tparam1): Use FALLTHROUGH to pacify GCC.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/eval.c b/src/eval.c
index c2cd6c60ea4..a6612b93e25 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -30,6 +30,15 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "dispextern.h"
 #include "buffer.h"
 
+/* CACHEABLE is ordinarily nothing, except it is 'volatile' if
+   necessary to cajole GCC into not warning incorrectly that a
+   variable should be volatile.  */
+#if defined GCC_LINT || defined lint
+# define CACHEABLE volatile
+#else
+# define CACHEABLE /* empty */
+#endif
+
 /* Chain of condition and catch handlers currently in effect.  */
 
 /* struct handler *handlerlist; */
@@ -1226,7 +1235,7 @@ internal_lisp_condition_case (Lisp_Object var, Lisp_Object bodyform,
                               Lisp_Object handlers)
 {
   struct handler *oldhandlerlist = handlerlist;
-  volatile ptrdiff_t clausenb = 0;
+  ptrdiff_t CACHEABLE clausenb = 0;
 
   CHECK_SYMBOL (var);