From 5c993bf8e8cde97fe82c6d6eec4befeb1527bdac Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 26 Feb 2026 10:25:51 +0300
Subject: [PATCH] strconv: fix common_parse_int not giving result when needed
 (fixes #17031)

---
 vlib/strconv/atoi.v      | 10 +++++++---
 vlib/strconv/atoi_test.v |  7 +++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/vlib/strconv/atoi.v b/vlib/strconv/atoi.v
index fbcc3ea14..07689fb99 100644
--- a/vlib/strconv/atoi.v
+++ b/vlib/strconv/atoi.v
@@ -190,11 +190,15 @@ pub fn common_parse_int(_s string, base int, _bit_size int, error_on_non_digit b
 	// TODO: check should u64(bit_size-1) be size of int (32)?
 	cutoff := u64(1) << u64(bit_size - 1)
 	if !neg && un >= cutoff {
-		// return error('parse_int: range error ${s0}')
+		if error_on_high_digit {
+			return error('common_parse_int: integer overflow ${_s}')
+		}
 		return i64(cutoff - u64(1))
 	}
 	if neg && un > cutoff {
-		// return error('parse_int: range error ${s0}')
+		if error_on_high_digit {
+			return error('common_parse_int: integer overflow ${_s}')
+		}
 		return -i64(cutoff)
 	}
 	return if neg { -i64(un) } else { i64(un) }
@@ -213,7 +217,7 @@ pub fn common_parse_int(_s string, base int, _bit_size int, error_on_non_digit b
 // correspond to int, int8, int16, int32, and int64.
 // If bitSize is below 0 or above 64, an error is returned.
 pub fn parse_int(_s string, base int, _bit_size int) !i64 {
-	return common_parse_int(_s, base, _bit_size, true, true)
+	return common_parse_int(_s, base, _bit_size, true, false)
 }
 
 // atoi_common_check perform basics check on string to parse:
diff --git a/vlib/strconv/atoi_test.v b/vlib/strconv/atoi_test.v
index e54ea520b..bc54a7b83 100644
--- a/vlib/strconv/atoi_test.v
+++ b/vlib/strconv/atoi_test.v
@@ -341,6 +341,13 @@ fn test_parse_int() {
 	}
 }
 
+fn test_common_parse_int_error_on_high_digit() {
+	assert strconv.common_parse_int('9223372036854775808', 0, 64, false, true) or { 1 } == 1
+	assert strconv.common_parse_int('-9223372036854775809', 0, 64, false, true) or { 1 } == 1
+	assert strconv.common_parse_int('9223372036854775808', 0, 64, false, false) or { 1 } == max_i64
+	assert strconv.common_parse_int('-9223372036854775809', 0, 64, false, false) or { 1 } == min_i64
+}
+
 fn test_common_parse_uint2() {
 	mut result, mut error := strconv.common_parse_uint2('1', 10, 8)
 	assert result == 1
-- 
2.39.5