Add comment to the safety of the uint8 cast (open-telemetry#5819)

MadVikingGod · XSAM · web-flow · commit 074bc28c5af3 · 2024-06-28T10:06:03.000-07:00
Closes open-telemetry#5666 Closes open-telemetry#5571 Closes open-telemetry#5626 The conversion referenced in both issues is impossible to overflow. This PR leaves a comment to that effect. Co-authored-by: Aaron Clawson <MadVikingGod@users.noreply.github.com> Co-authored-by: Sam Xie <sam@samxie.me>
diff --git a/samplers/probability/consistent/tracestate.go b/samplers/probability/consistent/tracestate.go
@@ -198,6 +198,7 @@ func parseNumber(key string, input string, maximum uint8) (uint8, error) {
 	if value > uint64(maximum) {
 		return maximum + 1, parseError(key, strconv.ErrRange)
 	}
+	// `value` is strictly less then the uint8 maximum. This cast is safe.
 	return uint8(value), nil
 }
 

Original file line number	Diff line number	Diff line change
`@@ -198,6 +198,7 @@ func parseNumber(key string, input string, maximum uint8) (uint8, error) {`
`198`	`198`	`if value > uint64(maximum) {`
`199`	`199`	`return maximum + 1, parseError(key, strconv.ErrRange)`
`200`	`200`	`}`
	`201`	+ // `value` is strictly less then the uint8 maximum. This cast is safe.
`201`	`202`	`return uint8(value), nil`
`202`	`203`	`}`
`203`	`204`