CURRENT (r253984) buildworld fails: contrib/bind9/bin/dig/dighost.c:4340:27: error: passing 'const char *' to parameter of type 'void *' discards qualifiers
Buildword on r253984 fails ins BIND9: cc -O2 -pipe -O3 -march=native -I/usr/src/usr.sbin/pkg_install/create/../lib -pipe -O3 -std=gnu99 -Qunused-arguments -fstack-protector -Wsystem-headers -Werror -Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wno-uninitialized -Wno-pointer-sign -Wno-empty-body -Wno-string-plus-int -Wno-tautological-compare -Wno-unused-value -Wno-parentheses-equality -Wno-unused-function -Wno-conversion -Wformat=2 -Wno-format-extra-args -Wno-format-nonliteral -Werror -c /usr/src/usr.sbin/pkg_install/create/perform.c --- usr.bin.all__D --- /usr/src/usr.bin/dig/../../contrib/bind9/bin/dig/dighost.c:4340:27: error: passing 'const char *' to parameter of type 'void *' discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers] isc_buffer_init(buffer, str, len); [...] signature.asc Description: PGP signature
Re: const char *
:don't think there's any way to get rid of the warning without changing :the declarations. : :In my opinion, the use of -Wcast-qual is bogus. Often the whole :point of a cast is to remove a qualifier such as const. It's one :thing to warn when that's done implicitly, and quite another thing to :warn when the programmer has clearly expressed his intent through the :use of a cast. : :John :-- : John Polstra j...@polstra.com There are only a few cases where cast-qual is bogus. 99% of the warnings it generated were quite real. Maybe not bugs, but definitely programming by misadventure. Volatile and const are only going to become more important as we get deeper into the SMP issues. Especially volatile. cast-qual is necessary to keep people from making bozo mistakes. Matthew Dillon dil...@backplane.com To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-current in the body of the message
Re: const char *
../../dev/usb/ukbd.c: In function `ukbd_detach':
../../dev/usb/ukbd.c:373: warning: cast discards `const' from pointer
target type
...
It is a consequence of the following type definition:
(sys/bus_private.h)
struct device {
...
const char* desc; /* driver specific description */
...
}
One problem I have is that a string like that might be produced by
concatenating a few strings together. In the case of USB the desc is
the string returned by the device. At attach the string is created and
malloc()-ed, at detach free()-ed.
At the sys/bus*.h (bus) level, `desc' is just a string. It is const
mainly so that callers can pass a literal string to device_set_desc()
without getting a warning from -Wcast-qual. Unfortunately, this prevents
the bus level from helping you keep track of how the string was created.
The warning could be avoided using a table of the original (non-const)
addresses of the (malloc()ed) strings passed to device_set_desc().
This is a bit much to avoid a harmless warning, but you would need to
do it if not all strings were malloc()ed.
The warning can be avoided by (ab)using a variant union. I plan to use
a suitably macroised version of this to fix warnings for library functions.
Bruce
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Re: const char *
Matthew Dillon wrote: : :In my opinion, the use of -Wcast-qual is bogus. Often the whole :point of a cast is to remove a qualifier such as const. It's one :thing to warn when that's done implicitly, and quite another thing :to warn when the programmer has clearly expressed his intent through :the use of a cast. There are only a few cases where cast-qual is bogus. 99% of the warnings it generated were quite real. Maybe not bugs, but definitely programming by misadventure. Volatile and const are only going to become more important as we get deeper into the SMP issues. Especially volatile. cast-qual is necessary to keep people from making bozo mistakes. I would find -Wcast-qual tolerable if it behaved just a little bit differently. It should allow without complaint explicit casts which change _only_ the constness. For example, casting from const char * to char * explicitly would be OK. But casting from, say, const char * to void * would still produce a warning. This would make it possible to get rid of the warnings in those cases where it made sense to cast away const (e.g., dealing with bad but standard interfaces). The above is more or less how C++'s const_castT(x) construct works. John --- John Polstra j...@polstra.com John D. Polstra Co., Inc.Seattle, Washington USA Nobody ever went broke underestimating the taste of the American public. -- H. L. Mencken To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-current in the body of the message
const char *
With the new efforts in getting rid of all the warnings in the kernel
compiles I have a problem with the following warning:
../../dev/usb/ukbd.c: In function `ukbd_detach':
../../dev/usb/ukbd.c:373: warning: cast discards `const' from pointer
target type
produced by the following two lines in the USB code:
(dev/usb/ukbd.c)
ukbd_detach(device_t self)
{
...
const char *devinfo = device_get_desc(self);
...
free((void *)devinfo, M_USB);
It is a consequence of the following type definition:
(sys/bus_private.h)
struct device {
...
const char* desc; /* driver specific description */
...
}
One problem I have is that a string like that might be produced by
concatenating a few strings together. In the case of USB the desc is
the string returned by the device. At attach the string is created and
malloc()-ed, at detach free()-ed.
Anyone savvy enough to tell me what I need to change in the USB code to
get rid of the warning?
Cheers,
Nick
FreeBSD USB Driver Development
--
e-mail: n_hi...@freebsd.org
home page: http://www.etla.net/~n_hibma/usb/usb.pl
mailing list: usb-...@egroups.com
To Unsubscribe: send mail to majord...@freebsd.org
with unsubscribe freebsd-current in the body of the message
Re: const char *
In article pine.bsf.3.96.990220224447.327a-100...@henny.plazza.it,
Nick Hibma hi...@skylink.it wrote:
With the new efforts in getting rid of all the warnings in the kernel
compiles I have a problem with the following warning:
../../dev/usb/ukbd.c: In function `ukbd_detach':
../../dev/usb/ukbd.c:373: warning: cast discards `const' from pointer
target type
produced by the following two lines in the USB code:
(dev/usb/ukbd.c)
ukbd_detach(device_t self)
{
...
const char *devinfo = device_get_desc(self);
...
free((void *)devinfo, M_USB);
...
Anyone savvy enough to tell me what I need to change in the USB code to
get rid of the warning?
The warning comes because -Wcast-qual is on the command line. I
don't think there's any way to get rid of the warning without changing
the declarations.
In my opinion, the use of -Wcast-qual is bogus. Often the whole
point of a cast is to remove a qualifier such as const. It's one
thing to warn when that's done implicitly, and quite another thing to
warn when the programmer has clearly expressed his intent through the
use of a cast.
John
--
John Polstra j...@polstra.com
John D. Polstra Co., Inc.Seattle, Washington USA
Nobody ever went broke underestimating the taste of the American public.
-- H. L. Mencken
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with unsubscribe freebsd-current in the body of the message
