https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83431
--- Comment #3 from Matteo Croce <mcroce at redhat dot com> ---
I can reproduce it with this snippet:
void f()
{
const char *dir = "a";
const char file[50] = "b";
char buf[4];
snprintf(buf, sizeof(buf), "%s/%s", dir, file);
}
$ gcc -Wall -c buf.c
buf.c: In function ‘f’:
buf.c:8:33: warning: ‘%s’ directive output may be truncated writing up to 49
bytes into a region of size 3 [-Wformat-truncation=]
8 | snprintf(buf, sizeof(buf), "%s/%s", dir, file);
| ^~ ~~~~~~~~~~~
buf.c:8:2: note: ‘snprintf’ output 2 or more bytes (assuming 51) into a
destination of size 4
8 | snprintf(buf, sizeof(buf), "%s/%s", dir, file);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/9/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin
--enable-initfini-array --with-isl --enable-offload-targets=nvptx-none
--without-cuda-driver --enable-gnu-indirect-function --enable-cet
--with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 9.1.1 20190503 (Red Hat 9.1.1-1) (GCC)
Regards,
Matteo Croce
