On Tue, Apr 25, 2023 at 07:51:57AM -0500, Eric Blake wrote:
> On Tue, Apr 25, 2023 at 10:52:45AM +1000, David Leonard wrote:
> > On Mon, 24 Apr 2023, Harald van Dijk wrote:
> > > coreutils/readlink.c:91:27: warning: adding 'unsigned int' to a string
> > > does not append to the string [-Wstring-plus-int]
> > > printf("%s%s", buf, "\n" + (opt & 1));
> > > ~~~~~^~~~~~~~~~~
> > > coreutils/readlink.c:91:27: note: use array indexing to silence this
> > > warning
> > > printf("%s%s", buf, "\n" + (opt & 1));
> > > ^
> > > & [ ]
> > >
> > > I am not sure what busybox's intent is here. If busybox decides that
> > > this warning is useless, it would be nice if it got suppressed reliably.
> >
> > Alternatively, avoid warnings with this construction which gives pretty
> > good size results:
> >
> > if (opt)
>
> That's not the same as 'if (opt & 1)'. As such, you are not comparing
> apples to oranges...
>
> > $ cat f1.c
> > #include <stdio.h>
> >
> > /* suppress trailing newline when opt */
> > int f1(int opt, char buf[]) {
> > #if defined(T0)
> > if (opt) printf("%s", buf); else printf("%s\n", buf);
> > #elif defined(T1)
> > if (opt) fputs(buf, stdout); else puts(buf);
> > #elif defined(T2)
> > printf("%s%s", buf, "\n" + (opt & 1));
>
> Of the four tests, T2 is the only one with correct semantics.
>
> > #elif defined(T3)
> > printf("%s%s", buf, opt ? "" : "\n");
> > #else
> > # error "forgot to -DTx"
> > #endif
The baseline in the existing coreutils/readlink.c is:
printf((opt & 1) ? "%s" : "%s\n", buf);
which I don't see in your tests.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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