Subject: Re: [PATCH v2 2/2] parseopt: check for duplicate long names and numerical options

From: René Scharfe <[email-masked]>
Date: Sat, 28 Feb 2026 12:28:39 +0100

On 2/28/26 11:58 AM, Jeff King wrote:
> On Sat, Feb 28, 2026 at 10:19:16AM +0100, René Scharfe wrote:
> 
>> +static void parse_options_check_harder(const struct option *opts)
>> +{
>> +	struct strset long_names = STRSET_INIT;
>> +	for (; opts->type != OPTION_END; opts++) {
>> +		if (opts->long_name) {
>> +			if (!strset_add(&long_names, opts->long_name))
>> +				optbug(opts, "long name already used");
>> +		}
>> +	}
>> +	BUG_if_bug("invalid 'struct option'");
>> +	strset_clear(&long_names);
>> +}
> 
> I confirmed on my silly pathological case that invoking rev-parse with a
> real option shows no slowdown, and we now pay the same 10ms cost to show
> "-h".
> 
> Your other email made me wonder how the sorted-array solution might
> perform (patch below). It shaves off 2ms of those 10. Probably not worth
> caring about for "-h" output (which is already spending another 5-10ms
> to generate the output, versus a normal parse).
Curious; sorting performs worse on my machine (Apple M1, 1 is 2cc719175,
2 is patch 2 v2, 3 is your patch on top):

Benchmark 1: ./git_main rev-parse --parseopt -- -h <input
  Time (mean ± σ):      77.5 ms ±   0.4 ms    [User: 73.1 ms, System: 3.5 ms]
  Range (min … max):    76.8 ms …  78.5 ms    37 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: ./git_strset rev-parse --parseopt -- -h <input
  Time (mean ± σ):      82.6 ms ±   0.3 ms    [User: 77.7 ms, System: 3.9 ms]
  Range (min … max):    82.1 ms …  83.7 ms    34 runs

  Warning: Ignoring non-zero exit code.

Benchmark 3: ./git_qsort rev-parse --parseopt -- -h <input
  Time (mean ± σ):      85.6 ms ±   0.2 ms    [User: 81.2 ms, System: 3.5 ms]
  Range (min … max):    85.3 ms …  86.5 ms    33 runs

  Warning: Ignoring non-zero exit code.

Summary
  ./git_main rev-parse --parseopt -- -h <input ran
    1.07 ± 0.01 times faster than ./git_strset rev-parse --parseopt -- -h <input
    1.10 ± 0.01 times faster than ./git_qsort rev-parse --parseopt -- -h <input