no-overflow-check-after-overflow

Disallow overflow tests that perform the overflowing operation first

Comparing an unsigned arithmetic result with an operand observes overflow only after it has occurred.
Instead, you MUST use checked arithmetic or the overflow flag returned by an overflowing operation.

- Category: correctness
- Level: error
- Fix: suggestion
- Scope: module

Reported

function overflows(left: uint32, right: uint32): boolean {
    return left + right < left;
}
Accepted

function overflows(left: uint32, right: uint32): boolean {
    return left.checkedAdd(right) === undefined;
}
Prior art

- Clippy · panickingoverflowchecks

language/linter/src/rules/correctness/nooverflowcheckafteroverflow.rs:8