From: Pedro Alves <pedro@codesourcery.com>
To: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: gdb-patches@sourceware.org,
Joel Brobecker <brobecker@adacore.com>,
Eli Zaretskii <eliz@gnu.org>,
Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: [patch 1/9]#2 Rename `enum target_signal' to target_signal_t
Date: Wed, 01 Sep 2010 20:06:00 -0000 [thread overview]
Message-ID: <201009012059.36696.pedro@codesourcery.com> (raw)
In-Reply-To: <20100901191843.GA27558@host1.dyn.jankratochvil.net>
On Wednesday 01 September 2010 20:18:43, Jan Kratochvil wrote:
> On Wed, 01 Sep 2010 21:07:55 +0200, Pedro Alves wrote:
> > I wonder if switching on "-Wc++-compat" wouldn't catch these (at
> > least with recent enough gccs) and be more productive than
> > switching to a struct. /me ducks.
>
> I wanted to argue with this great point myself but during my tests (gcc-4.5)
> enum unfortunately IS compatible with int even in C++ (tried -Wall/-pedantic
> etc.). I haven't checked the C++ spec.
I think "int signal = TARGET_SIGNAL_TRAP" would be valid C++, while
"enum gdb_signal signal = SIGTRAP" would not. I thought the latter would
be the most common scenario to catch though. Maybe not.
Anyway, personally, I'd just do a enum target_signal/enum gdb_signal
rename, and stay with that.
But, here's another idea of how to get compiler warnings/errors,
that I think is more transparent to code throughout:
/* An empty struct. It's the instances we care about. */
struct gdb_signal_1
{
};
/* An array of all defined gdb signals. */
const struct gdb_signal_1 gdb_signals[NUM_GDB_SIGNALS];
/* gdb code uses gdb_signal, not gdb_signal_1. gdb_signal is a
pointer. */
typedef struct gdb_signal_1 * gdb_signal;
/* Define the constants. */
#define TARGET_SIGNAL_0 (&gdb_signals[0])
#define TARGET_SIGNAL_TRAP (&gdb_signals[5])
#define TARGET_SIGNAL_FOO (&gdb_signals[FOO])
...
Then, you can do this:
gdb_signal signal = TARGET_SIGNAL_TRAP;
and still do this:
for (gdb_signal foo = TARGET_SIGNAL_0; sig < TARGET_SIGNAL_LAST; sig++)
do_things(foo);
... all as before. But these:
int sig = TARGET_SIGNAL_TRAP;
gdb_signal sig = SIGTRAP;
gdb_signal sig = TARGET_SIGNAL_TRAP;
if (sig < SIGTRAP)
do_things ();
... give out a warnings, fatal with -Werror.
Getting at the signal integer is simply:
#define GDB_SIGNAL_NUMBER(gdb_sig) \
(((gdb_sig) - TARGET_SIGNAL_0) / sizeof (gdb_sig))
All the other macros TARGET_SIGNAL_EQ|NE|GT|... disappear.
Here's a compilable example:
$ cat sig.c
#include <signal.h>
struct gdb_signal_1 {};
typedef struct gdb_signal_1 * gdb_signal;
struct gdb_signal_1 signals[10];
#define TARGET_SIGNAL_TRAP (&signals[5])
int main ()
{
gdb_signal sig = TARGET_SIGNAL_TRAP;
int sig2 = SIGTRAP;
if (sig == sig2)
{
}
sig = sig2;
sig2 = sig;
return 0;
}
$ gcc sig.c -o sig.o -c -Wall
sig.c: In function ‘main’:
sig.c:16: warning: comparison between pointer and integer
sig.c:20: warning: assignment makes pointer from integer without a cast
sig.c:21: warning: assignment makes integer from pointer without a cast
--
Pedro Alves
next prev parent reply other threads:[~2010-09-01 19:59 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-30 7:11 Jan Kratochvil
2010-08-30 8:14 ` Mark Kettenis
2010-08-30 8:24 ` Jan Kratochvil
2010-08-30 10:09 ` Eli Zaretskii
2010-08-30 11:11 ` Mark Kettenis
2010-08-30 14:08 ` Joel Brobecker
2010-08-31 18:28 ` Jan Kratochvil
2010-08-31 18:45 ` Mark Kettenis
2010-09-01 2:03 ` Joel Brobecker
2010-09-01 18:18 ` Joel Brobecker
2010-09-01 18:30 ` Jan Kratochvil
2010-09-01 18:38 ` Pedro Alves
2010-09-01 18:45 ` Jan Kratochvil
2010-09-01 18:40 ` Joel Brobecker
2010-09-01 18:51 ` Jan Kratochvil
2010-09-01 19:08 ` Pedro Alves
2010-09-01 19:28 ` Jan Kratochvil
2010-09-01 20:06 ` Pedro Alves [this message]
2010-09-01 20:06 ` Daniel Jacobowitz
2010-09-01 20:10 ` Pedro Alves
2010-09-02 9:46 ` Pedro Alves
2010-09-02 14:01 ` Jan Kratochvil
2010-09-02 15:36 ` Joel Brobecker
2010-09-02 19:02 ` Pedro Alves
2010-09-02 20:46 ` Jan Kratochvil
2010-09-07 18:59 ` Jan Kratochvil
2010-09-02 16:02 ` Joel Brobecker
2010-09-02 17:04 ` Jan Kratochvil
2010-09-06 0:29 ` Jan Kratochvil
2010-09-06 13:30 ` Pedro Alves
2010-09-06 14:52 ` Jan Kratochvil
2010-09-08 23:42 ` Jan Kratochvil
2010-09-01 20:23 ` Jan Kratochvil
2010-09-01 20:30 ` Mark Kettenis
2010-09-01 20:47 ` Pedro Alves
2010-09-01 21:32 ` Joseph S. Myers
2010-09-01 19:12 ` Joel Brobecker
2010-09-01 22:37 ` Tom Tromey
2010-08-30 14:11 ` Eli Zaretskii
2010-08-30 17:34 ` Michael Snyder
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