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-rw-r--r--include/stddef.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/stddef.h b/include/stddef.h
index 275e53c..0e10989 100644
--- a/include/stddef.h
+++ b/include/stddef.h
@@ -28,6 +28,18 @@
* the same width and ISO C does not specify it this
* way), use to indicate that a pointer does not point
* to anything.
+ *
+ * Note on considerations of `NULL` being harmful:
+ * It is important to remember than `sizeof(NULL)`
+ * does not equal `sizeof(int)` on all machines.
+ * Therefore, in variadic arguments, it is important
+ * not to substitute `x` for `x != NULL`. This
+ * would cause horrible bugs. If you insist on not
+ * using `NULL`, correct substitutions would be
+ * `!!x` or `x != 0`.
+ * Note that `NULL` is genuinely harmful in C++,
+ * but excessive use of C++, and especially it
+ * features, is harmful too.
*/
#ifndef NULL
# define NULL ((void*)0)