In ISO C11, the operand of @code{alignof}/@code{_Alignof} must be a
parenthesized type. Recent versions of GCC support an extension in
which the operand can also be a unary expression, as with
-@code{sizeof}. We don't know of any compilers that support
-@code{alignof}/@code{_Alignof} without also supporting this extension;
-if you find one please let us know.
+@code{sizeof}. The Gnulib substitute does not support this extension.
@item
@code{_Alignas} and @code{alignas} are not always supported;
on platforms lacking support, the