[PATCH 02/20] trace: use 'ignore_value()' instead of a dummy variable

["Daniel P. Berrangé" <berrange@redhat.com>]

This pattern is more concise than using a dummy variable which
in turn needs annotating as unused.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 trace/ftrace.c | 3 +--
 trace/simple.c | 9 ++++-----
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/trace/ftrace.c b/trace/ftrace.c
index 6875faedb9c..c1ed6ad4454 100644
--- a/trace/ftrace.c
+++ b/trace/ftrace.c
@@ -41,7 +41,6 @@ static int find_mount(char *mount_point, const char *fstype)
 void ftrace_write(const char *fmt, ...)
 {
     char ftrace_buf[MAX_TRACE_STRLEN];
-    int unused __attribute__ ((unused));
     int trlen;
     va_list ap;
 
@@ -50,7 +49,7 @@ void ftrace_write(const char *fmt, ...)
     va_end(ap);
 
     trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);
-    unused = write(trace_marker_fd, ftrace_buf, trlen);
+    ignore_value(write(trace_marker_fd, ftrace_buf, trlen));
 }
 
 bool ftrace_init(void)
diff --git a/trace/simple.c b/trace/simple.c
index c0aba00cb7f..e148ca44530 100644
--- a/trace/simple.c
+++ b/trace/simple.c
@@ -163,7 +163,6 @@ static gpointer writeout_thread(gpointer opaque)
     } dropped;
     unsigned int idx = 0;
     int dropped_count;
-    size_t unused __attribute__ ((unused));
     uint64_t type = TRACE_RECORD_TYPE_EVENT;
 
     for (;;) {
@@ -179,13 +178,13 @@ static gpointer writeout_thread(gpointer opaque)
             } while (!g_atomic_int_compare_and_exchange(&dropped_events,
                                                         dropped_count, 0));
             dropped.rec.arguments[0] = dropped_count;
-            unused = fwrite(&type, sizeof(type), 1, trace_fp);
-            unused = fwrite(&dropped.rec, dropped.rec.length, 1, trace_fp);
+            ignore_value(fwrite(&type, sizeof(type), 1, trace_fp));
+            ignore_value(fwrite(&dropped.rec, dropped.rec.length, 1, trace_fp));
         }
 
         while (get_trace_record(idx, &recordptr)) {
-            unused = fwrite(&type, sizeof(type), 1, trace_fp);
-            unused = fwrite(recordptr, recordptr->length, 1, trace_fp);
+            ignore_value(fwrite(&type, sizeof(type), 1, trace_fp));
+            ignore_value(fwrite(recordptr, recordptr->length, 1, trace_fp));
             writeout_idx += recordptr->length;
             free(recordptr); /* don't use g_free, can deadlock when traced */
             idx = writeout_idx % TRACE_BUF_LEN;
-- 
2.55.0