On 2023-06-09 09:11, Eli Zaretskii wrote:
From: Martin Dorey <martin.do...@hitachivantara.com>
CC: "bug-make@gnu.org" <bug-make@gnu.org>
Date: Fri, 9 Jun 2023 06:32:28 +0000
msip_labels:
#include <stdint.h>
intptr_t _get_osfhandle(int);
typedef void* HANDLE;
HANDLE fn() {
return (HANDLE)_get_osfhandle(0);
}
martind@sirius:~/tmp/svensson-2023-06-08$ gcc -c -Wbad-function-cast make.c
make.c: In function ‘fn’:
make.c:7:10: warning: cast from function call of type ‘intptr_t {aka long int}’
to non-matching type ‘void *’ [-Wbad-function-cast]
return (HANDLE)_get_osfhandle(0);
^
martind@sirius:~/tmp/svensson-2023-06-08$
That's gcc-6.3, but it's much the same in every version I tested from gcc-4.4
to gcc-10. A random version's man page,
https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Warning-Options.html, explains the
flag as to:
Warn when a function call is cast to a non-matching type. For example, warn if
a call to a function returning an integer type is cast to a pointer type.
I fear they mean exactly what they say there. So, while you might call it a
mistake, I don't think it's an accident.
https://stackoverflow.com/a/35308713/18096 has some explanation of why it might
sometimes be useful... and how it could be sidestepped by a change to Gnu Make,
like our new friend wished for.
Yes, it sounds like -Wbad-function-cast will always emit a warning in
such cases, and one cannot use it with the likes of _get_osfhandle,
which _require_ such casts.
You can, of course, work around it; the following compiles without a
warning:
#include <stdint.h>
intptr_t _get_osfhandle(int);
typedef void* HANDLE;
HANDLE fn() {
intptr_t handle = _get_osfhandle(0);
return (HANDLE)handle;
}
Okay, lets go this way to fix the warning to allow building with
-Wbad-function-cast.
The only thing left, that I don't know how to handle, is the use of O() where
the 3rd parameter is not a string literal.
src/job.c: In function 'create_batch_file':
src/job.c:365:3: error: format not a string literal and no format arguments
[-Werror=format-security]
O (fatal, NILF, error_string);
^
is it okay to change this to: fatal (NILF, 0, error_string);
or is there a better way to get around this warning?
