C Integer Promotions & Conversions

When to use

• Writing arithmetic mixing int, unsigned, size_t, char, short, or literals.
• Reviewing comparisons between signed and unsigned values.
• Calculating buffer/allocation sizes from potentially large inputs (CVE-2022-0185, CVE-2016-8617).
• Diagnosing "works on 64-bit, breaks on 32-bit" (size_t narrowing).

When not to use

• Pure unsigned-only arithmetic with no narrowing (still check overflow — see c-undefined-behavior).
• Floating point conversion (different rules — FLP).
• C++ — use cpp-object-lifecycle for C++-specific integer issues (ES.100-107).

What the agent often gets wrong