les/api.go: bad loop var capture

[suchfun]

Describe the bug

we use tool scopelint to scan this repo, and find some warnings.

In les/api.go: 258-310 line:
loop var is used in some anonymous functions, and these anonymous functions will be executed after the whole loop iteration.
but they always only use the last element in the loop instead of all of them.

	benchmarks := make([]requestBenchmark, len(setups))
	for i, setup := range setups {
		if t, ok := setup["type"].(string); ok {
			getInt := func(field string, def int) int {
				if value, ok := setup[field].(float64); ok {
					return int(value)
				}
				return def
			}
			getBool := func(field string, def bool) bool {
				if value, ok := setup[field].(bool); ok {
					return value
				}
				return def
			}
			switch t {
			case "header":
				benchmarks[i] = &benchmarkBlockHeaders{
					amount:  getInt("amount", 1),
					skip:    getInt("skip", 1),
					byHash:  getBool("byHash", false),
					reverse: getBool("reverse", false),
				}
			case "body":
				benchmarks[i] = &benchmarkBodiesOrReceipts{receipts: false}
			case "receipts":
				benchmarks[i] = &benchmarkBodiesOrReceipts{receipts: true}
			case "proof":
				benchmarks[i] = &benchmarkProofsOrCode{code: false}
			case "code":
				benchmarks[i] = &benchmarkProofsOrCode{code: true}
			case "cht":
				benchmarks[i] = &benchmarkHelperTrie{
					bloom:    false,
					reqCount: getInt("amount", 1),
				}
			case "bloom":
				benchmarks[i] = &benchmarkHelperTrie{
					bloom:    true,
					reqCount: getInt("amount", 1),
				}
			case "txSend":
				benchmarks[i] = &benchmarkTxSend{}
			case "txStatus":
				benchmarks[i] = &benchmarkTxStatus{}
			default:
				return nil, errUnknownBenchmarkType
			}
		} else {
			return nil, errUnknownBenchmarkType
		}
	}
	rs := api.server.handler.runBenchmark(benchmarks, passCount, time.Millisecond*time.Duration(length))

Expected behavior

value of loop var is different value from each iteration when getInt/getBool is called instead of a single value.

how to fix it

	benchmarks := make([]requestBenchmark, len(setups))
	for i, setup := range setups {

                setup := setup   // add this line

		if t, ok := setup["type"].(string); ok {
			getInt := func(field string, def int) int {
				if value, ok := setup[field].(float64); ok {
					return int(value)
				}
				return def
			}
			getBool := func(field string, def bool) bool {
				if value, ok := setup[field].(bool); ok {
					return value
				}
				return def
			}
			switch t {
			case "header":
				benchmarks[i] = &benchmarkBlockHeaders{
					amount:  getInt("amount", 1),
					skip:    getInt("skip", 1),
					byHash:  getBool("byHash", false),
					reverse: getBool("reverse", false),
				}
			case "body":
				benchmarks[i] = &benchmarkBodiesOrReceipts{receipts: false}
			case "receipts":
				benchmarks[i] = &benchmarkBodiesOrReceipts{receipts: true}
			case "proof":
				benchmarks[i] = &benchmarkProofsOrCode{code: false}
			case "code":
				benchmarks[i] = &benchmarkProofsOrCode{code: true}
			case "cht":
				benchmarks[i] = &benchmarkHelperTrie{
					bloom:    false,
					reqCount: getInt("amount", 1),
				}
			case "bloom":
				benchmarks[i] = &benchmarkHelperTrie{
					bloom:    true,
					reqCount: getInt("amount", 1),
				}
			case "txSend":
				benchmarks[i] = &benchmarkTxSend{}
			case "txStatus":
				benchmarks[i] = &benchmarkTxStatus{}
			default:
				return nil, errUnknownBenchmarkType
			}
		} else {
			return nil, errUnknownBenchmarkType
		}
	}
	rs := api.server.handler.runBenchmark(benchmarks, passCount, time.Millisecond*time.Duration(length))

[fjl]

Please send a pull request!

[holiman]

I'm closing this. Feel free to open a PR -- I also think that this is fixed in my PR to add more linters: #24783 . No need to have it open as a ticket too, IMO