From 7ed9ee2992ef15789d82ab961f525d9bb2885204 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 23 Apr 2026 17:47:30 +0300
Subject: [PATCH] benchmark: fix nixos V panic: string.repeat: count is
 negative: -26  (fixes #10974)

---
 vlib/benchmark/benchmark.v      | 17 ++++++++++++++---
 vlib/benchmark/benchmark_test.v | 11 +++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/vlib/benchmark/benchmark.v b/vlib/benchmark/benchmark.v
index 0cd2ad264..cdc7cb653 100644
--- a/vlib/benchmark/benchmark.v
+++ b/vlib/benchmark/benchmark.v
@@ -4,6 +4,8 @@ import time
 import term
 import arrays
 
+const step_label_width = 5
+
 pub const b_ok = term.ok_message('OK  ')
 pub const b_fail = term.fail_message('FAIL')
 pub const b_skip = term.warn_message('SKIP')
@@ -166,6 +168,7 @@ pub:
 pub fn (b &Benchmark) step_message_with_label_and_duration(label string, msg string, sduration time.Duration,
 	opts MessageOptions) string {
 	timed_line := b.tdiff_in_ms(msg, sduration.microseconds())
+	flabel := format_step_label(label)
 	if b.nexpected_steps > 1 {
 		mut sprogress := ''
 		if b.nexpected_steps < 10 {
@@ -194,11 +197,19 @@ pub fn (b &Benchmark) step_message_with_label_and_duration(label string, msg str
 			}
 		}
 		if opts.preparation > 0 {
-			return '${label:-5s} [${sprogress}] C: ${f64(opts.preparation.microseconds()) / 1_000.0:7.1F} ms, R: ${timed_line}'
+			return '${flabel} [${sprogress}] C: ${f64(opts.preparation.microseconds()) / 1_000.0:7.1F} ms, R: ${timed_line}'
 		}
-		return '${label:-5s} [${sprogress}] ${timed_line}'
+		return '${flabel} [${sprogress}] ${timed_line}'
+	}
+	return '${flabel}${timed_line}'
+}
+
+fn format_step_label(label string) string {
+	visible_len := term.strip_ansi(label).len
+	if visible_len >= step_label_width {
+		return label
 	}
-	return '${label:-5s}${timed_line}'
+	return label + ' '.repeat(step_label_width - visible_len)
 }
 
 // step_message_with_label returns a string describing the current step using current time as duration.
diff --git a/vlib/benchmark/benchmark_test.v b/vlib/benchmark/benchmark_test.v
index 3871fa4ea..fec00d39c 100644
--- a/vlib/benchmark/benchmark_test.v
+++ b/vlib/benchmark/benchmark_test.v
@@ -1,5 +1,6 @@
 import time
 import benchmark
+import term
 
 fn test_measure() {
 	mut b := benchmark.start()
@@ -62,3 +63,13 @@ fn test_total_message() {
 	assert !res2.contains(' Max: ')
 	assert !res2.contains(' Avg: ')
 }
+
+fn test_step_message_handles_ansi_label_longer_than_label_width() {
+	mut b := benchmark.start()
+	ansi_fail_label := '\x1b[41m\x1b[1m\x1b[37m FAIL \x1b[39m\x1b[22m\x1b[49m'
+	long_cmd := 'command: /nix/store/' + 'x'.repeat(90) + '-vlang/build/source/v -o v_g -g cmd/v'
+	message := b.step_message_with_label(ansi_fail_label, long_cmd)
+
+	assert term.strip_ansi(message).contains('FAIL')
+	assert message.contains(long_cmd)
+}
-- 
2.39.5