Change semantics of empty list equality

I considered making empty lists of undetermined type equal to all empty
lists, but then the comparison would not be transitive

3 files changed, 8 insertions, 8 deletions

diff --git a/include/tag_list.h b/include/tag_list.h
index af5a87d5ee..adb8623f45 100644
--- a/include/tag_list.h
+++ b/include/tag_list.h
@@ -161,8 +161,8 @@ public:
     /**
      * @brief Equality comparison for lists
      *
-     * Lists are considered equal if they contain equal tags. Empty lists
-     * are always considered equal to each other.
+     * Lists are considered equal if their content types and the contained tags
+     * are equal.
      */
     friend bool operator==(const tag_list& lhs, const tag_list& rhs);
     friend bool operator!=(const tag_list& lhs, const tag_list& rhs);
diff --git a/src/tag_list.cpp b/src/tag_list.cpp
index 34112b3eca..7900f9872e 100644
--- a/src/tag_list.cpp
+++ b/src/tag_list.cpp
@@ -132,8 +132,6 @@ auto tag_list::cend() const   -> const_iterator { return tags.cend(); }
 
 bool operator==(const tag_list& lhs, const tag_list& rhs)
 {
-    if(lhs.size() == 0 && rhs.size() == 0)
-        return true;
     return lhs.el_type_ == rhs.el_type_ && lhs.tags == rhs.tags;
 }
 
diff --git a/test/nbttest.cpp b/test/nbttest.cpp
index 347dad3e3a..c253a5d59b 100644
--- a/test/nbttest.cpp
+++ b/test/nbttest.cpp
@@ -297,19 +297,21 @@ void test_tag_list()
     ASSERT(list.size() == 0 && list.el_type() == tag_type::String);
     EXPECT_EXCEPTION(list.push_back(tag_short(25)), std::bad_cast);
     EXPECT_EXCEPTION(list.push_back(value(nullptr)), std::bad_cast);
-    
+
     list.reset();
     ASSERT(list.el_type() == tag_type::Null);
     list.emplace_back<tag_int>(17);
     ASSERT(list.el_type() == tag_type::Int);
-    
+
     list.reset(tag_type::Float);
     ASSERT(list.el_type() == tag_type::Float);
     list.emplace_back<tag_float>(17.0f);
     ASSERT(list == tag_list({17.0f}));
 
-    ASSERT(tag_list() == tag_list(tag_type::Int));
-    ASSERT(tag_list(tag_type::Short) == tag_list(tag_type::Int));
+    ASSERT(tag_list() != tag_list(tag_type::Int));
+    ASSERT(tag_list() == tag_list());
+    ASSERT(tag_list(tag_type::Short) != tag_list(tag_type::Int));
+    ASSERT(tag_list(tag_type::Short) == tag_list(tag_type::Short));
 
     tag_list short_list = tag_list::of<tag_short>({25, 36});
     ASSERT(short_list.el_type() == tag_type::Short);