Eehhh, what the hell is going on here!?

SELECT
    printf("0x%x", (1 << 63) - 2),
    printf("0x%x", (1 << 63) - 1),
    printf("0x%x",  1 << 63     ),
    printf("0x%x", (1 << 63) + 1),
    printf("0x%x", (1 << 63) + 2)

SQLite yields:

0x8000000000000000 (instead of 0x7ffffffffffffffe)
0x8000000000000000 (instead of 0x7fffffffffffffff)
0x8000000000000000 (correct)
0x8000000000000001 (correct)
0x8000000000000002 (correct)

Huh!? O_o Am I stupid? What am I missing here? Or is this actually a bug? :-?

With 62 bits, everything is spot on:

0x3ffffffffffffffe
0x3fffffffffffffff
0x4000000000000000
0x4000000000000001
0x4000000000000002

And 64 bits rather unsurprisingly also yield:

0xfffffffffffffffe
0xffffffffffffffff
0x0
0x1
0x2