Re: [PATCH] kernel: Fix ftrace.c compiler warning when callingftrace_nop_replace()

From: Steven Rostedt
Date: Mon May 23 2011 - 09:08:40 EST

On Sun, 2011-05-22 at 18:36 -0700, H. Peter Anvin wrote:
> On 05/22/2011 06:19 PM, Eduardo Silva wrote:
> > the function ftrace_nop_replace() returns a 'static const unsigned char *'
> > value, so when the caller perform a direct assignment to a
> > 'static unsigned char *', the compiler raise the following warning message:
> >
> > ftrace.c:308:6: warning: assignment discards qualifiers from pointer target type
> > ftrace.c:318:6: warning: assignment discards qualifiers from pointer target type
> >
> > Adding the proper casts the message goes away.
> >
> > Signed-off-by: Eduardo Silva <edsiper@xxxxxxxxx>
> This quiets a warning of something that potentially looks like a real
> bug. Perhaps "new" should be const?

Although there is no real bug here, I hate these "hide the warning"

The real solution is to change all the users into const *. This should
be doable as the new and old pointers are not modified.

And remember:

char *changes;
const char *no_changes;

no_changes = changes; /* is OK! (no compiler warnings) */

changes = no_changes; /* is not OK. (compiler will warn). */

-- Steve

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