https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90191
Bug ID: 90191
Summary: [9 regression] -Wformat-overflow depends on --param
max-jump-thread-duplication-stmts=17
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: dimhen at gmail dot com
Target Milestone: ---
r265568 PASS
r265754 FAIL
r270458 FAIL
Warn if compiled with "-O2 --param max-jump-thread-duplication-stmts=17"
And not warn if compiled with -O2
Original code fill & printf() 2 vectors of chars (pseudo-code see below)
-- If second vector is in "if() {}" then warning emitted.
-- If second vector is out of "if() {}" then no warning produced.
-- if printf() divided into 2 printf there are no warning.
$ cat a.ii
extern "C" int printf(const char *...);
struct i {
void j(char *p1, int) { delete p1; }
};
struct q {
typedef char &d;
};
struct t {
static char *u();
};
template <typename e, typename ab, typename g, typename h> void ad(e, ab, g,
h);
char *m;
struct v {
struct w {
char *l;
};
v(int p1) {
int o = p1, a = o;
m = a ? t::u() : 0;
n.l = m;
}
~v() {
char *c = n.l, *p = c;
int f = 0;
i k;
k.j(p, f);
}
w n;
};
int s;
struct x : v {
x() : v(y()) {
i b;
ad(0, 0, s, b);
}
q::d operator[](int p1) { return *(n.l + p1); }
static int y();
};
unsigned ap();
char r;
static int av() {
{
x d;
if (0)
goto ay;
char &e = d[0];
printf("%s = %s\n", &r, &e);
}
ay:
return 0;
}
unsigned ap() {
av();
return 0;
}
$ /usr/local/gcc_current/bin/g++ -O2 -fpreprocessed -Wall -Wextra -c a.ii
$ /usr/local/gcc_current/bin/g++ -O2 --param
max-jump-thread-duplication-stmts=17 -fpreprocessed -Wall -Wextra -c a.ii
In function 'int av()',
inlined from 'unsigned int ap()' at a.ii:53:5:
a.ii:47:11: warning: '%s' directive argument is null [-Wformat-overflow=]
47 | printf("%s = %s\n", &r, &e);
| ~~~~~~^~~~~~~~~~~~~~~~~~~~~
Original code looks as
size_t l1, l2, sel;
if(foo_1(&l1))
goto err;
if(foo_2(&sel, &l2))
goto err;
std::vector<char> v(l1);
if(bar_1(&v[0])
goto err;
if(sel) {
std::vector<char> w(l2); // <--- if move out of block then warning disappears
if(bar_2(&w[0]))
goto err;
printf("%s = %s\n", &v[0], &w[0]); // <-- if divided to 2 calls then warning
disappears
return;
}
err:
return;
$ /usr/local/gcc_current/bin/g++ -v
Using built-in specs.
COLLECT_GCC=/usr/local/gcc_current/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/gcc_current/libexec/gcc/x86_64-pc-linux-gnu/9.0.1/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
Target: x86_64-pc-linux-gnu
Configured with: /home/dimhen/src/gcc_current/configure
--prefix=/usr/local/gcc_current --enable-checking=yes,df,fold,rtl,extra
--enable-languages=c,c++,lto --disable-multilib --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-gnu-unique-object
--enable-linker-build-id --with-linker-hash-style=gnu --enable-plugin
--enable-initfini-array --with-isl --enable-offload-targets=nvptx-none
--without-cuda-driver --enable-gnu-indirect-function --with-tune=native
Thread model: posix
gcc version 9.0.1 20190419 (experimental) [trunk revision 270458] (GCC)
