Re: [PATCH 4/5] treewide: Spell ASSERT() as assert()

On Tue, Mar 17, 2026 at 01:02:34AM +0100, Stefano Brivio wrote:

On Mon, 16 Mar 2026 16:46:28 +1100 David Gibson wrote:

...

+++ b/util.h @@ -73,10 +73,14 @@ void abort_with_msg(const char *fmt, ...) * Therefore, avoid using the usual do while wrapper we use to force the macro * to act like a single statement requiring a ';'. */ -#define ASSERT_WITH_MSG(expr, ...) \ +#define assert_with_msg(expr, ...) \ ((expr) ? (void)0 : abort_with_msg(__VA_ARGS__)) -#define ASSERT(expr) \ - ASSERT_WITH_MSG((expr), "ASSERTION FAILED in %s (%s:%d): %s", \ +/* The standard library assert() hits our seccomp filter and dies before it can + * actually print a message. So, replace it with our own version. + */ +#undef assert +#define assert(expr) \ + assert_with_msg((expr), "ASSERTION FAILED in %s (%s:%d): %s", \ __func__, __FILE__, __LINE__, STRINGIFY(expr))

While looking this up to make sure it's specified as a macro (it is, and this builds against musl as well), I realised that POSIX.1-2024 says:

https://pubs.opengroup.org/onlinepubs/9799919799/functions/assert.html

Forcing a definition of the name NDEBUG, either from the compiler command line or with the preprocessor control statement #define NDEBUG ahead of the #include statement, shall stop assertions from being compiled into the program.

...so, I wonder, now that it's called assert(), should we define it as "do { } while(0)" #ifdef NDEBUG, for correctness (and maybe somebody has obscure usages for NDEBUG which we shouldn't sabotage)?

I like the idea in principle. Actually implementing it turns out to be kind of a pain in the arse, because if we actually try to compile with -DNDEBUG then we get a much of warnings due to reaching the end of functions (assert(0) stopped us otherwise) or unused variables (they're only used in the assert expression or message). A project for some other time, I think.

This will conflict with "[PATCH v2 3/3] vu_common: Move iovec management into vu_collect()" by the way, but I'll take care of it, if it still conflicts by the time I merge it.

-- Stefano

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson