From 2bbed8cc0698e946a084425d8762fb89685b80f7 Mon Sep 17 00:00:00 2001
From: elsid <elsid.mail@gmail.com>
Date: Mon, 2 Jan 2023 17:03:03 +0100
Subject: [PATCH] =?UTF-8?q?Fix=20gcc=20warning:=20array=20subscript=205=20?=
 =?UTF-8?q?is=20outside=20array=20bounds=20of=20=E2=80=98const=20char=20[5?=
 =?UTF-8?q?]=E2=80=99?=
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In function ‘bool ESM::operator==(const FixedString<capacity>&, const T* const&) [with long unsigned int capacity = 5; T = char; <template-parameter-1-3> = void]’,
    inlined from ‘testing::AssertionResult testing::internal::CmpHelperEQ(const char*, const char*, const T1&, const T2&) [with T1 = ESM::FixedString<5>; T2 = const char*]’ at /home/elsid/dev/googletest/build/gcc/release/install/include/gtest/gtest.h:1358:11,
    inlined from ‘static testing::AssertionResult testing::internal::EqHelper::Compare(const char*, const char*, const T1&, const T2&) [with T1 = ESM::FixedString<5>; T2 = const char*; typename std::enable_if<((! std::is_integral<_Tp>::value) || (! std::is_pointer<_Dp>::value))>::type* <anonymous> = 0]’ at /home/elsid/dev/googletest/build/gcc/release/install/include/gtest/gtest.h:1377:64,
    inlined from ‘virtual void {anonymous}::EsmFixedString_equality_operator_for_not_convertible_to_uint32_with_const_char_pointer_Test::TestBody()’ at apps/openmw_test_suite/esm/test_fixed_string.cpp:165:9:
components/esm/esmcommon.hpp:134:19: warning: array subscript 5 is outside array bounds of ‘const char [5]’ [-Warray-bounds]
  134 |         return rhs[capacity] == '\0';
      |                ~~~^
apps/openmw_test_suite/esm/test_fixed_string.cpp: In member function ‘virtual void {anonymous}::EsmFixedString_equality_operator_for_not_convertible_to_uint32_with_const_char_pointer_Test::TestBody()’:
apps/openmw_test_suite/esm/test_fixed_string.cpp:164:20: note: at offset 5 into object ‘other’ of size 5
  164 |         const char other[5] = { 'a', 'b', 'c', 'd', '\0' };
      |                    ^~~~~
---
 .../esm/test_fixed_string.cpp                 | 15 ++++++++++++++
 components/esm/esmcommon.hpp                  | 20 ++++++++++++-------
 2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/apps/openmw_test_suite/esm/test_fixed_string.cpp b/apps/openmw_test_suite/esm/test_fixed_string.cpp
index f3d4071c28..76ed346daa 100644
--- a/apps/openmw_test_suite/esm/test_fixed_string.cpp
+++ b/apps/openmw_test_suite/esm/test_fixed_string.cpp
@@ -170,4 +170,19 @@ namespace
         const ESM::FixedString<5> value("abcd");
         EXPECT_EQ(value, std::string("abcd"));
     }
+
+    TEST(EsmFixedString, equality_operator_for_not_convertible_to_uint32_with_string_view)
+    {
+        const ESM::FixedString<5> value("abcd");
+        const std::string other("abcd");
+        EXPECT_EQ(value, std::string_view(other));
+    }
+
+    TEST(EsmFixedString, equality_operator_should_not_get_out_of_bounds)
+    {
+        ESM::FixedString<5> value;
+        const char other[5] = { 'a', 'b', 'c', 'd', 'e' };
+        std::memcpy(value.mData, other, sizeof(other));
+        EXPECT_EQ(value, static_cast<const char*>(other));
+    }
 }
diff --git a/components/esm/esmcommon.hpp b/components/esm/esmcommon.hpp
index f272fa553e..e12a4703ce 100644
--- a/components/esm/esmcommon.hpp
+++ b/components/esm/esmcommon.hpp
@@ -121,23 +121,23 @@ namespace ESM
         }
     };
 
-    template <std::size_t capacity, class T, typename = std::enable_if_t<std::is_same_v<T, char>>>
-    inline bool operator==(const FixedString<capacity>& lhs, const T* const& rhs) noexcept
+    template <std::size_t capacity>
+    inline bool operator==(const FixedString<capacity>& lhs, std::string_view rhs) noexcept
     {
-        for (std::size_t i = 0; i < capacity; ++i)
+        for (std::size_t i = 0, n = std::min(rhs.size(), capacity); i < n; ++i)
         {
             if (lhs.mData[i] != rhs[i])
                 return false;
             if (lhs.mData[i] == '\0')
                 return true;
         }
-        return rhs[capacity] == '\0';
+        return rhs.size() <= capacity || rhs[capacity] == '\0';
     }
 
-    template <std::size_t capacity>
-    inline bool operator==(const FixedString<capacity>& lhs, const std::string& rhs) noexcept
+    template <std::size_t capacity, class T, typename = std::enable_if_t<std::is_same_v<T, char>>>
+    inline bool operator==(const FixedString<capacity>& lhs, const T* const& rhs) noexcept
     {
-        return lhs == rhs.c_str();
+        return lhs == std::string_view(rhs, capacity);
     }
 
     template <std::size_t capacity, std::size_t rhsSize>
@@ -156,6 +156,12 @@ namespace ESM
         return lhs.toInt() == rhs.toInt();
     }
 
+    template <class T, typename = std::enable_if_t<std::is_same_v<T, char>>>
+    inline bool operator==(const FixedString<4>& lhs, const T* const& rhs) noexcept
+    {
+        return lhs == std::string_view(rhs, 5);
+    }
+
     template <std::size_t capacity, class Rhs>
     inline bool operator!=(const FixedString<capacity>& lhs, const Rhs& rhs) noexcept
     {