Paul Eggert wrote:
> The first step is to add a new module "verify", which defines macros
> verify(EXPR) and verify_expr(EXPR) that act like assert(EXPR) except
> they check EXPR at compile-time, not at run-time. verify(EXPR) is for
> declaration contexts, and verify_expr is for expression contexts.
Thanks a lot for making this generally available!
At first sight, using a bitfield width instead of an array size, to
avoid multiple-definition errors, seems awfully cool. But it does not
work:
$ cat foo.c
#include "verify.h"
verify (1 + 1 == 2); verify (1 + 1 == 2);
$ gcc -O -c foo.c
foo.c:2: conflicting types for `verify_function_2'
foo.c:2: previous declaration of `verify_function_2'
Here's a fix that makes this work. OK to commit?
Bruno
diff -c -3 -r1.1 verify.h
*** verify.h 22 Sep 2005 22:56:29 -0000 1.1
--- verify.h 23 Sep 2005 09:48:54 -0000
***************
*** 16,22 ****
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
! /* Written by Paul Eggert and Jim Meyering. */
#ifndef VERIFY_H
# define VERIFY_H 1
--- 16,22 ----
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
! /* Written by Paul Eggert, Jim Meyering, Bruno Haible. */
#ifndef VERIFY_H
# define VERIFY_H 1
***************
*** 26,36 ****
/* A type that is valid if and only if R is nonzero.
R should be an integer constant expression.
! verify_type__ and verify_error_if_negative_size__ are symbols that
! are private to this header file. */
! # define verify_type__(R) \
! struct { int verify_error_if_negative_size__ : (R) ? 1 : -1; }
/* Verify requirement R at compile-time, as a declaration.
R should be an integer constant expression.
--- 26,36 ----
/* A type that is valid if and only if R is nonzero.
R should be an integer constant expression.
! verify_array_type__ and verify_pointer_type__ are symbols that are
! private to this header file. */
! # define verify_array_type__(R) int [(R) ? 1 : -1]
! # define verify_pointer_type__(R) int (*) [(R) ? 1 : -1]
/* Verify requirement R at compile-time, as a declaration.
R should be an integer constant expression.
***************
*** 44,50 ****
no conforming compiler will reject them outright. */
# define verify(R) \
! extern verify_type__ (R) GL_CONCAT (verify_function_, __LINE__) (void)
/* Verify requirement R at compile-time, as an expression.
R should be an integer constant expression.
--- 44,50 ----
no conforming compiler will reject them outright. */
# define verify(R) \
! extern void GL_CONCAT (verify_function_, __LINE__) (verify_array_type__
(R))
/* Verify requirement R at compile-time, as an expression.
R should be an integer constant expression.
***************
*** 52,57 ****
This macro can be used in some contexts where verify cannot, and vice
versa.
Return void. */
! # define verify_expr(R) ((void) ((verify_type__ (R) *) 0))
#endif
--- 52,57 ----
This macro can be used in some contexts where verify cannot, and vice
versa.
Return void. */
! # define verify_expr(R) ((void) ((verify_pointer_type__ (R)) 0))
#endif
_______________________________________________
bug-gnulib mailing list
bug-gnulib@gnu.org
http://lists.gnu.org/mailman/listinfo/bug-gnulib
