Fix base-prefixed integer unpacking

[dduan]

Summary

• Reject base-prefixed integer tokens that omit digits before unpacking.
• Add regression coverage for x = 0x.

Validation

• Not run in this split branch per instruction; this commit was already verified before PR splitting.

[github-actions]

�[33mWarning: running with the Swift runtime interposer on Linux to avoid the Swift 6.3 runtime hook crash. See https://github.com/ordo-one/benchmark/issues/349�[0m

Comparing results between 'main' and 'pull_request'

Host 'runnervm5mmn9' with 4 'x86_64' processors with 15 GB memory, running:
#18~24.04.1-Ubuntu SMP Thu May 28 16:39:11 UTC 2026

TOMLDecoderBenchmarks

Decode toml.io example metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	63	64	64	65	70	90	130	7213
pull_request	63	64	64	68	86	110	140	6924
Δ	0	0	0	3	16	20	10	-289
Improvement %	0	0	0	-5	-23	-22	-8	-289

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	765	765	765	765	765	765	765	7213
pull_request	765	765	765	765	765	765	765	6924
Δ	0	0	0	0	0	0	0	-289
Improvement %	0	0	0	0	0	0	0	-289

Parse toml.io example metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ns) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	5079	5243	5283	5351	5431	10583	36187	10000
pull_request	5160	5271	5303	5351	6355	12455	60267	10000
Δ	81	28	20	0	924	1872	24080	0
Improvement %	-2	-1	0	0	-17	-18	-67	0

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	31	31	31	31	31	31	31	10000
pull_request	31	31	31	31	31	31	31	10000
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

decode canada.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	258	258	258	263	265	265	265	4
pull_request	260	260	264	265	268	268	268	4
Δ	2	2	6	2	3	3	3	0
Improvement %	-1	-1	-2	-1	-1	-1	-1	0

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	1286	1286	1286	1286	1286	1286	1286	4
pull_request	1286	1286	1286	1286	1286	1286	1286	4
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

decode twitter.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	8689	9495	9511	9527	9560	9688	9688	105
pull_request	8727	9486	9503	9544	9585	9789	10024	105
Δ	38	-9	-8	17	25	101	336	0
Improvement %	0	0	0	0	0	-1	-3	0

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	113	113	113	113	113	113	113	105
pull_request	113	113	113	113	113	113	113	105
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

parse GitHub events archive metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	125	126	126	128	134	134	134	8
pull_request	122	122	122	125	133	133	133	9
Δ	-3	-4	-4	-3	-1	-1	-1	1
Improvement %	2	3	3	2	1	1	1	1

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	394	394	394	394	394	394	394	8
pull_request	394	394	394	394	394	394	394	9
Δ	0	0	0	0	0	0	0	1
Improvement %	0	0	0	0	0	0	0	1

parse canada.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	15	16	16	16	16	25	25	63
pull_request	15	15	16	16	16	24	24	64
Δ	0	-1	0	0	0	-1	-1	1
Improvement %	0	6	0	0	0	4	4	1

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	47	47	47	47	47	47	47	63
pull_request	47	47	47	47	47	47	47	64
Δ	0	0	0	0	0	0	0	1
Improvement %	0	0	0	0	0	0	0	1

parse twitter.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	2268	2288	2294	2304	2316	2445	3412	424
pull_request	2259	2275	2286	2341	2361	2423	3397	424
Δ	-9	-13	-8	37	45	-22	-15	0
Improvement %	0	1	0	-2	-2	1	0	0

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	7736	7736	7736	7736	7736	7736	7736	424
pull_request	7736	7736	7736	7736	7736	7736	7736	424
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0