lib: Make sure NULL is defined to be ((void *)0)

This avoids us having to do explicit (void *)NULL casts in e.g.
io_add(..., NULL) context parameter.

diff --git a/src/lib/compat.h b/src/lib/compat.h
index f6bb6e3526031035d29dcadc10b087cce91f8f37..937b09722be4e45a73486e36bab2450cbe800a9a 100644 (file)
--- a/src/lib/compat.h
+++ b/src/lib/compat.h
@@ -11,6 +11,13 @@
 #  define LLONG_MAX 9223372036854775807LL
 #endif
 
+/* We really want NULL to be a pointer, since we have various type-checks
+   that may result in compiler warnings/errors if it's not. */
+#ifndef __cplusplus
+#  undef NULL
+#  define NULL ((void *)0)
+#endif
+
 #ifndef __cplusplus
 #ifdef HAVE__BOOL
 typedef _Bool bool;