https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120954
Bug ID: 120954
Summary: [15 Regression] False positive -Warray-bounds=2
warning
Product: gcc
Version: 15.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: sirl at gcc dot gnu.org
Target Milestone: ---
This small code snippet warns with r15-9921 (r15-9866 was still OK):
static const int map01[32] = { 11, 12, 13, 14, 15 };
static const int map02[32] = { 21, 22, 23, 24, 25 };
static const int map03[32] = { 31, 32, 33, 34, 35 };
static const int map11[32] = { 111, 112, 113, 114, 115 };
static const int map12[32] = { 121, 122, 123, 124, 125 };
static const int map13[32] = { 131, 132, 133, 134, 135 };
int test(int n, int ver)
{
int r = 0;
if (n >= 0 && n < 32) {
r = ((ver >= 4) ? ((ver >= 0x65) ? map01 : map02 ) : map03)[n];
} else if (n >= 0x100 && n < 0x120) {
r = ((ver >= 4) ? ((ver >= 0x65) ? map11 : map12 ) : map13)[n -
0x100];
};
return r;
}
# g++-15 -c -O2 -Warray-bounds=2 test-Warray-bounds.cpp
test-Warray-bounds.cpp: In function 'int test(int, int)':
test-Warray-bounds.cpp:16:86: warning: intermediate array offset -256 is
outside array bounds of 'const int [32]' [-Warray-bounds=]
16 | r = ((ver >= 4) ? ((ver >= 0x65) ? map11 : map12 ) :
map13)[n - 0x100];
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
This one also might have been caused by
commit r15-9896-g7fdf47538a659f6af8dadbecbb63c8a226b63754
Author: Jakub Jelinek <ja...@redhat.com>
Date: Tue Jul 1 15:28:10 2025 +0200
c++: Fix up cp_build_array_ref COND_EXPR handling [PR120471]
But this time I'm not very confident about that. Compiling this a C code
doesn't warn.
