From 5a277895010cf8fb060d4fddf7daeafb53aa551b Mon Sep 17 00:00:00 2001
From: HedgehogInTheCPP <a.rainman@gmail.com>
Date: Tue, 25 Aug 2026 04:51:45 +0300
Subject: [PATCH] add optimization from
 https://github.com/fastfloat/fast_float/pull/402

---
 include/fast_float/digit_comparison.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/fast_float/digit_comparison.h b/include/fast_float/digit_comparison.h
index f9019b8..710aa6e 100644
--- a/include/fast_float/digit_comparison.h
+++ b/include/fast_float/digit_comparison.h
@@ -322,8 +322,9 @@ parse_mantissa(bigint &result, const parsed_number_string_t<UC> &num) noexcept {
       add_native(result, static_cast<limb>(powers_of_ten_uint64[counter]),
                  value);
       bool truncated = is_truncated(p, pend);
-      if (num.fraction.ptr != nullptr) {
-        truncated |= is_truncated(num.fraction);
+      // A nonzero integer suffix already determines the rounding direction.
+      if (!truncated && num.fraction.ptr != nullptr) {
+        truncated = is_truncated(num.fraction);
       }
       if (truncated) {
         round_up_bigint(result, digits);