From 754c677b0bbf3ea6c7d2a73c93848f1b0d68c91e Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 20 Jun 2011 16:54:15 +0930 Subject: lib: import ccan modules for tdb2 Imported from git://git.ozlabs.org/~ccan/ccan init-1161-g661d41f Signed-off-by: Rusty Russell --- lib/ccan/build_assert/_info | 49 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) create mode 100644 lib/ccan/build_assert/_info (limited to 'lib/ccan/build_assert/_info') diff --git a/lib/ccan/build_assert/_info b/lib/ccan/build_assert/_info new file mode 100644 index 0000000000..0906af07e6 --- /dev/null +++ b/lib/ccan/build_assert/_info @@ -0,0 +1,49 @@ +#include +#include +#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: + * #include + * #include + * + * struct foo { + * char string[5]; + * int x; + * }; + * + * static 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; + * } + * + * License: LGPL (2 or any later version) + * Author: Rusty Russell + */ +int main(int argc, char *argv[]) +{ + if (argc != 2) + return 1; + + if (strcmp(argv[1], "depends") == 0) + /* Nothing. */ + return 0; + + return 1; +} -- cgit