GCC 8.0+ <https://gcc.gnu.org/gcc-8/changes.html> introduces a new
warning about unsafe macros expanding to multiple statements used
as a body of a statement such as if, else, while, switch, or for.
In combination with -Werror this can cause the compilation to fail:
|In file included from xmalloc.c:37:
|xmalloc.c: In function 'xmalloc':
|system.h:39:2: error: macro expands to multiple statements [-Werror=multistatement-macros]
| fflush(stdout); \
| ^~~~~~
|xmalloc.c:52:5: note: in expansion of macro 'error'
| error (EXIT_FAILURE, 0, _("memory exhausted"));
| ^~~~~
|xmalloc.c:51:3: note: some parts of macro expansion are not guarded by this 'if' clause
| if (p == NULL)
| ^~
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
--- a/lib/system.h
+++ b/lib/system.h
-@@ -30,7 +30,16 @@
+@@ -30,7 +30,18 @@
#define LIB_SYSTEM_H 1
#include <errno.h>
+#else
+#include "err.h"
+#include <stdio.h>
-+#define error(status, errno, ...) \
-+ fflush(stdout); \
-+ warn(__VA_ARGS__); \
-+ if (status) exit(status)
++#define error(status, errno, ...) \
++ do { \
++ fflush(stdout); \
++ warn(__VA_ARGS__); \
++ if (status) exit(status); \
++ } while(0)
+#endif
#include <stddef.h>
#include <stdint.h>
#include <sys/param.h>
-@@ -38,6 +47,10 @@
+@@ -38,6 +49,10 @@
#include <byteswap.h>
#include <unistd.h>