[RFC][PATCH] notmuch: Workaround to allow ignoring non-void function return.

[David Edmondson <dme@dme.org>]

---

The mechanism used here works for me in an isolated test case and no
warnings appear when using it as below, but I'm unsure why the
original warning that it is intended to address didn't appear when I
build. Any thoughts?

 compat/compat.h |    6 ++++++
 notmuch-new.c   |    2 +-
 notmuch-show.c  |    2 +-
 notmuch-tag.c   |    2 +-
 4 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/compat/compat.h b/compat/compat.h
index 7767fe8..1160301 100644
--- a/compat/compat.h
+++ b/compat/compat.h
@@ -30,6 +30,12 @@
 extern "C" {
 #endif
 
+#ifdef __GNUC__
+#define ignore_result(x) ({ __typeof__(x) z = x; (void) sizeof (z); })
+#else /* !__GNUC__ */
+#define ignore_result(x) x
+#endif /* __GNUC__ */
+
 #if !HAVE_GETLINE
 #include <stdio.h>
 #include <unistd.h>
diff --git a/notmuch-new.c b/notmuch-new.c
index 3512de7..0ac04cc 100644
--- a/notmuch-new.c
+++ b/notmuch-new.c
@@ -67,7 +67,7 @@ handle_sigint (unused (int sig))
 {
     static char msg[] = "Stopping...         \n";
 
-    (void) write(2, msg, sizeof(msg)-1);
+    ignore_result(write(STDERR_FILENO, msg, sizeof(msg)-1));
     interrupted = 1;
 }
 
diff --git a/notmuch-show.c b/notmuch-show.c
index 19fb49f..681f778 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -866,7 +866,7 @@ do_show_single (void *ctx,
 
 	while (!feof (file)) {
 	    size = fread (buf, 1, sizeof (buf), file);
-	    (void) fwrite (buf, size, 1, stdout);
+	    ignore_result(fwrite (buf, size, 1, stdout));
 	}
 
 	fclose (file);
diff --git a/notmuch-tag.c b/notmuch-tag.c
index 292c5da..2cbfdc3 100644
--- a/notmuch-tag.c
+++ b/notmuch-tag.c
@@ -26,7 +26,7 @@ static void
 handle_sigint (unused (int sig))
 {
     static char msg[] = "Stopping...         \n";
-    (void) write(2, msg, sizeof(msg)-1);
+    ignore_result(write(STDERR_FILENO, msg, sizeof(msg)-1));
     interrupted = 1;
 }
 
-- 
1.7.7.3