From 05e4e581b58cb64c34965f2dbbc87115d656584a Mon Sep 17 00:00:00 2001
From: frosch <frosch@openttd.org>
Date: Sun, 20 Apr 2025 19:44:13 +0200
Subject: [PATCH] Codefix: StringConsumer integer parsing failed for the most
 negative value, which has no positive equivalent.

---
 src/core/string_consumer.hpp  |  4 ++--
 src/tests/string_consumer.cpp | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/core/string_consumer.hpp b/src/core/string_consumer.hpp
index e4e9145fa3..6e314d5489 100644
--- a/src/core/string_consumer.hpp
+++ b/src/core/string_consumer.hpp
@@ -813,10 +813,10 @@ private:
 
 			/* Try negative hex */
 			if (std::is_signed_v<T> && (src.starts_with("-0x") || src.starts_with("-0X"))) {
-				using Unsigned = std::make_signed_t<T>;
+				using Unsigned = std::make_unsigned_t<T>;
 				auto [len, uvalue] = ParseIntegerBase<Unsigned>(src.substr(3), 16, log_errors);
 				if (len == 0) return {};
-				T value = -uvalue;
+				T value = static_cast<T>(0 - uvalue);
 				if (value > 0) {
 					if (log_errors) LogError(fmt::format("Integer out of range: '{}'", src.substr(0, len + 3)));
 					return {};
diff --git a/src/tests/string_consumer.cpp b/src/tests/string_consumer.cpp
index 1cf470a0cc..c884cbc7f3 100644
--- a/src/tests/string_consumer.cpp
+++ b/src/tests/string_consumer.cpp
@@ -485,3 +485,18 @@ TEST_CASE("StringConsumer - invalid int")
 	consumer.SkipIntegerBase(0);
 	CHECK(consumer.ReadUtf8() == 'y');
 }
+
+TEST_CASE("StringConsumer - most negative")
+{
+	StringConsumer consumer("-80000000 -0x80000000 -2147483648"sv);
+	CHECK(consumer.PeekIntegerBase<uint32_t>(16) == std::pair<StringConsumer::size_type, uint32_t>(0, 0));
+	CHECK(consumer.PeekIntegerBase<int32_t>(16) == std::pair<StringConsumer::size_type, int32_t>(9, 0x80000000));
+	consumer.SkipIntegerBase(16);
+	CHECK(consumer.ReadUtf8() == ' ');
+	CHECK(consumer.PeekIntegerBase<uint32_t>(0) == std::pair<StringConsumer::size_type, uint32_t>(0, 0));
+	CHECK(consumer.PeekIntegerBase<int32_t>(0) == std::pair<StringConsumer::size_type, int32_t>(11, 0x80000000));
+	consumer.SkipIntegerBase(0);
+	CHECK(consumer.ReadUtf8() == ' ');
+	CHECK(consumer.PeekIntegerBase<uint32_t>(10) == std::pair<StringConsumer::size_type, uint32_t>(0, 0));
+	CHECK(consumer.PeekIntegerBase<int32_t>(10) == std::pair<StringConsumer::size_type, int32_t>(11, 0x80000000));
+}