gnulib/doc/posix-headers/assert.texi

@node assert.h
@section @file{assert.h}

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/assert.h.html}

Gnulib module: assert-h
@mindex assert-h

@mindex assert
@mindex verify
See also the Gnulib modules @code{assert} and @code{verify}.

Portability problems fixed by Gnulib:
@itemize
@item
On older C platforms @code{<assert.h>} must be included before using
@code{static_assert}.  For example, GCC versions before 13 do not
support the @code{static_assert} keyword that was standardized by C23.
@item
On older platforms @code{static_assert} does not allow the second
string-literal argument to be omitted.  For example, GCC versions
before 9.1 do not support the single-argument @code{static_assert}
that was standardized by C23 and C++17.
@item
Even-older platforms do not support @code{static_assert} at all.
For example, GCC versions before 4.6 and G++ versions before 4.3
do not support the two-argument form, which was standardized
by C11 and C++11.
@item
Older C platforms might not support the obsolescent
@code{_Static_assert} keyword or macro.
This portability problem should not matter with code using this
module, as such code should use @code{static_assert} instead.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
A @code{static_assert} can also
be used within a @code{struct} or @code{union} specifier, in place of
an ordinary declaration of a member of the struct or union.  The
Gnulib substitute can be used only as an ordinary declaration
in code intended to be portable to C99 or earlier.
@item
In C23 and C++11 and later, @code{static_assert} is a keyword.
In C11 and C17 it is a macro.  Any Gnulib substitute is also a macro.
@item
In C99 and later, @code{assert} can be applied to any scalar expression.
In C89, the argument to @code{assert} is of type @code{int}.
@end itemize