If currently two unsigned values are compared via `a - b`, in the case b
is actually bigger than a, the result will not be an negative number (as
-1 is expected) but a huge positive number as the subtraction is an
unsigned subtraction.
Avoid over-/underflow affected operations; use comparisons.
Modern compilers will generate sane code, like:
xor eax, eax
cmp rdi, rsi
seta al
sbb eax, 0
ret
Reasoning:
- implementation was unsound -- broke down when I added a fairly
basic macro definition expanding to a struct initializer in a *.c
file.
- made it way too easy (e.g. via otherwise totally innocuous git
commands) to end up with timestamps such that it always ran
MakeHeader.py but never used its output, leading to overbuild noise
when running what should be a null 'make'.
- but mostly: it's just an awkward way of dealing with C code.
Christian Göttsche
Benny Baumann
Daniel Lange
Zev Weiss
Hisham
Michael McConville