Skip memcpy(x, x) in qunique().
It has undefined behavior.  Follow the precedent of commit
No back-patch, since the
master branch alone has this function.
Discussion:
@@ -30,8 +30,9 @@ qunique(void *array, size_t elements, size_t width,
for (i = 1, j = 0; i < elements; ++i)
{
- if (compare(bytes + i * width, bytes + j * width) != 0)
- memcpy(bytes + ++j * width, bytes + i * width, width);
+ if (compare(bytes + i * width, bytes + j * width) != 0 &&
+ ++j != i)
+ memcpy(bytes + j * width, bytes + i * width, width);
}
return j + 1;
@@ -55,8 +56,9 @@ qunique_arg(void *array, size_t elements, size_t width,
for (i = 1, j = 0; i < elements; ++i)
{
- if (compare(bytes + i * width, bytes + j * width, arg) != 0)
- memcpy(bytes + ++j * width, bytes + i * width, width);
+ if (compare(bytes + i * width, bytes + j * width, arg) != 0 &&
+ ++j != i)
+ memcpy(bytes + j * width, bytes + i * width, width);
}
return j + 1;
