New macro MPFR_FALLTHROUGH to avoid -Wimplicit-fallthrough warnings

with GCC 7+. This macro also makes the code more readable by bringing
the attention on an unusual fallthrough in a switch case.
  * src/mpfr-impl.h: define this macro.
  * src/vasprintf.c: use this macro in a case of fallthrough.

git-svn-id: svn://scm.gforge.inria.fr/svn/mpfr/trunk@13467 280ebfd0-de03-0410-8827-d642c229c3f4

1 files changed, 1 insertions, 0 deletions

diff --git a/src/vasprintf.c b/src/vasprintf.c
index 831452bbe..be7dd79c3 100644
--- a/src/vasprintf.c
+++ b/src/vasprintf.c
@@ -2167,6 +2167,7 @@ mpfr_vasnprintf_aux (char **ptr, char *Buf, size_t size, const char *fmt,
               break;
             case 'N':
               ++fmt;
+              MPFR_FALLTHROUGH;
             default:
               spec.rnd_mode = MPFR_RNDN;
             }