False Overlapping read/write in memcpy()

[Martin Poupě]

Have code:

int K[2];
void test(void)
{
    memcpy(&K[0],&K[1],sizeof(K[0]));
}

Cppcheck 2.14 generates warning:
tmp.c:4:5: error: Overlapping read/write in memcpy() is undefined behavior [overlappingWriteFunction]
memcpy(&K[0],&K[1],sizeof(K[0]));
^
However there is no overlap.

[Andrew C Aitchison]

However this is OK:

int K[5];
void test(void)
{
    memcpy(&K[0],&K[4],sizeof(K[0]));

}

but destination &K[3]is not OK.

[Andrew C Aitchison]

long long K[9];
void test(void)
{
memcpy(&K[0],&K[8],sizeof(K[0]));
memcpy(&K[0],&K[7],sizeof(K[0]));
}
Complains about 8 but not 7.

[CHR]

https://trac.cppcheck.net/ticket/12638