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diff --git a/lib/ccan/typesafe_cb/_info b/lib/ccan/typesafe_cb/_info
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+++ b/lib/ccan/typesafe_cb/_info
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+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * typesafe_cb - macros for safe callbacks.
+ *
+ * The basis of the typesafe_cb header is typesafe_cb_cast(): a
+ * conditional cast macro.   If an expression exactly matches a given
+ * type, it is cast to the target type, otherwise it is left alone.
+ *
+ * This allows us to create functions which take a small number of
+ * specific types, rather than being forced to use a void *.  In
+ * particular, it is useful for creating typesafe callbacks as the
+ * helpers typesafe_cb(), typesafe_cb_preargs() and
+ * typesafe_cb_postargs() demonstrate.
+ *
+ * The standard way of passing arguments to callback functions in C is
+ * to use a void pointer, which the callback then casts back to the
+ * expected type.  This unfortunately subverts the type checking the
+ * compiler would perform if it were a direct call.  Here's an example:
+ *
+ *	static void my_callback(void *_obj)
+ *	{
+ *		struct obj *obj = _obj;
+ *		...
+ *	}
+ *	...
+ *		register_callback(my_callback, &my_obj);
+ *
+ * If we wanted to use the natural type for my_callback (ie. "void
+ * my_callback(struct obj *obj)"), we could make register_callback()
+ * take a void * as its first argument, but this would subvert all
+ * type checking.  We really want register_callback() to accept only
+ * the exactly correct function type to match the argument, or a
+ * function which takes a void *.
+ *
+ * This is where typesafe_cb() comes in: it uses typesafe_cb_cast() to
+ * cast the callback function if it matches the argument type:
+ *
+ *	void _register_callback(void (*cb)(void *arg), void *arg);
+ *	#define register_callback(cb, arg)				\
+ *		_register_callback(typesafe_cb(void, void *, (cb), (arg)), \
+ *				   (arg))
+ *
+ * On compilers which don't support the extensions required
+ * typesafe_cb_cast() and friend become an unconditional cast, so your
+ * code will compile but you won't get type checking.
+ *
+ * Example:
+ *	#include <ccan/typesafe_cb/typesafe_cb.h>
+ *	#include <stdlib.h>
+ *	#include <stdio.h>
+ *
+ *	// Generic callback infrastructure.
+ *	struct callback {
+ *		struct callback *next;
+ *		int value;
+ *		int (*callback)(int value, void *arg);
+ *		void *arg;
+ *	};
+ *	static struct callback *callbacks;
+ *
+ *	static void _register_callback(int value, int (*cb)(int, void *),
+ *				       void *arg)
+ *	{
+ *		struct callback *new = malloc(sizeof(*new));
+ *		new->next = callbacks;
+ *		new->value = value;
+ *		new->callback = cb;
+ *		new->arg = arg;
+ *		callbacks = new;
+ *	}
+ *	#define register_callback(value, cb, arg)			\
+ *		_register_callback(value,				\
+ *				   typesafe_cb_preargs(int, void *,	\
+ *						       (cb), (arg), int),\
+ *				   (arg))
+ *
+ *	static struct callback *find_callback(int value)
+ *	{
+ *		struct callback *i;
+ *
+ *		for (i = callbacks; i; i = i->next)
+ *			if (i->value == value)
+ *				return i;
+ *		return NULL;
+ *	}
+ *
+ *	// Define several silly callbacks.  Note they don't use void *!
+ *	#define DEF_CALLBACK(name, op)			\
+ *		static int name(int val, int *arg)	\
+ *		{					\
+ *			printf("%s", #op);		\
+ *			return val op *arg;		\
+ *		}
+ *	DEF_CALLBACK(multiply, *);
+ *	DEF_CALLBACK(add, +);
+ *	DEF_CALLBACK(divide, /);
+ *	DEF_CALLBACK(sub, -);
+ *	DEF_CALLBACK(or, |);
+ *	DEF_CALLBACK(and, &);
+ *	DEF_CALLBACK(xor, ^);
+ *	DEF_CALLBACK(assign, =);
+ *
+ *	// Silly game to find the longest chain of values.
+ *	int main(int argc, char *argv[])
+ *	{
+ *		int i, run = 1, num = argv[1] ? atoi(argv[1]) : 0;
+ *
+ *		for (i = 1; i < 1024;) {
+ *			// Since run is an int, compiler checks "add" does too.
+ *			register_callback(i++, add, &run);
+ *			register_callback(i++, divide, &run);
+ *			register_callback(i++, sub, &run);
+ *			register_callback(i++, multiply, &run);
+ *			register_callback(i++, or, &run);
+ *			register_callback(i++, and, &run);
+ *			register_callback(i++, xor, &run);
+ *			register_callback(i++, assign, &run);
+ *		}
+ *
+ *		printf("%i ", num);
+ *		while (run < 56) {
+ *			struct callback *cb = find_callback(num % i);
+ *			if (!cb) {
+ *				printf("-> STOP\n");
+ *				return 1;
+ *			}
+ *			num = cb->callback(num, cb->arg);
+ *			printf("->%i ", num);
+ *			run++;
+ *		}
+ *		printf("-> Winner!\n");
+ *		return 0;
+ *	}
+ *
+ * License: LGPL (2 or any later version)
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ */
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	return 1;
+}