Move modules to ccan/ tools to tools/

[ccan] / ccan / build_assert / _info.c

diff --git a/ccan/build_assert/_info.c b/ccan/build_assert/_info.c
new file mode 100644 (file)
index 0000000..555aae2
--- /dev/null
+++ b/ccan/build_assert/_info.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * build_assert - routines for build-time assertions
+ *
+ * This code provides routines which will cause compilation to fail should some
+ * assertion be untrue: such failures are preferable to run-time assertions,
+ * but much more limited since they can only depends on compile-time constants.
+ *
+ * These assertions are most useful when two parts of the code must be kept in
+ * sync: it is better to avoid such cases if possible, but seconds best is to
+ * detect invalid changes at build time.
+ *
+ * For example, a tricky piece of code might rely on a certain element being at
+ * the start of the structure.  To ensure that future changes don't break it,
+ * you would catch such changes in your code like so:
+ *
+ * Example:
+ *     char *foo_string(struct foo *foo)
+ *     {
+ *             // This trick requires that the string be first in the structure
+ *             BUILD_ASSERT(offsetof(struct foo, string) == 0);
+ *             return (char *)foo;
+ *     }
+ */
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               return 1;
+
+       if (strcmp(argv[1], "depends") == 0)
+               /* Nothing. */
+               return 0;
+
+       return 1;
+}