MBEDTLS_STATIC_ASSERT: make it work outside of a function
At the top level, the macro would have had to be used without a following
semicolon (except with permissive compilers that accept spurious semicolons
outside of a function), which is confusing to humans and indenters. Fix
that.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/common.h b/library/common.h
index 3936ffd..7bb2674 100644
--- a/library/common.h
+++ b/library/common.h
@@ -352,17 +352,19 @@
#endif
/* Always provide a static assert macro, so it can be used unconditionally.
- * It will expand to nothing on some systems.
- * Can be used outside functions (but don't add a trailing ';' in that case:
- * the semicolon is included here to avoid triggering -Wextra-semi when
- * MBEDTLS_STATIC_ASSERT() expands to nothing).
- * Can't use the C11-style `defined(static_assert)` on FreeBSD, since it
+ * It does nothing on systems where we don't know how to define a static assert.
+ */
+/* Can't use the C11-style `defined(static_assert)` on FreeBSD, since it
* defines static_assert even with -std=c99, but then complains about it.
*/
#if defined(static_assert) && !defined(__FreeBSD__)
-#define MBEDTLS_STATIC_ASSERT(expr, msg) static_assert(expr, msg);
+#define MBEDTLS_STATIC_ASSERT(expr, msg) static_assert(expr, msg)
#else
-#define MBEDTLS_STATIC_ASSERT(expr, msg)
+/* Make sure `MBEDTLS_STATIC_ASSERT(expr, msg);` is valid both inside and
+ * outside a function. We choose a struct declaration, which can be repeated
+ * any number of times and does not need a matching definition. */
+#define MBEDTLS_STATIC_ASSERT(expr, msg) \
+ struct ISO_C_does_not_allow_extra_semicolon_outside_of_a_function
#endif
#if defined(__has_builtin)