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)
fputs(buf, stdout);
else
puts(buf);
The rest of this email is cc/size experiment results.
$ ./cc-size -c f1.c -Os
cc -c f1.c -Os
-DT0 -DT1 -DT2 -DT3
aarch64 1584 -80 -8 +48
arm 1008 -48 -20 +0
mips 1396 -72 +8 +64
x86_64 1520 -80 -32 +0
gcc 1552 -96 +8 +72
clang 1280 -80 +0 +72
The numbers represent the increase in byte size of f1.o compared to when
compiled with baseline -DT0.
$ 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));
#elif defined(T3)
printf("%s%s", buf, opt ? "" : "\n");
#else
# error "forgot to -DTx"
#endif
}
The compilers were:
aarch64-linux-musl-gcc (GCC) 11.2.0
arm-linux-musleabi-gcc (GCC) 11.2.0
mips-linux-musl-gcc (GCC) 11.2.0
x86_64-linux-musl-gcc (GCC) 11.2.0
gcc (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0
Ubuntu clang version 14.0.0-1ubuntu1 (x86_64-pc-linux-gnu)
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