Don't return reference on copy assignment operators

We prefer to prevent using chained assignment (`T a = b = c = T();`) as this
can lead to confusing code and subtle bugs.

According to https://en.wikipedia.org/wiki/Assignment_operator_(C%2B%2B), C++
allows any arbitrary return type, so this is standard compliant.

This could be re-assessed if/when we have an actual need for a behavior more
akin to that of the C++ STL, for now this PR simply changes a handful of
cases which were inconsistent with the rest of the codebase (`void` return
type was already the most common case prior to this commit).

5 files changed, 7 insertions, 14 deletions

diff --git a/core/templates/local_vector.h b/core/templates/local_vector.h
index 3854e1e94c..4ec08821f8 100644
--- a/core/templates/local_vector.h
+++ b/core/templates/local_vector.h
@@ -234,19 +234,17 @@ public:
 			data[i] = p_from.data[i];
 		}
 	}
-	inline LocalVector &operator=(const LocalVector &p_from) {
+	inline void operator=(const LocalVector &p_from) {
 		resize(p_from.size());
 		for (U i = 0; i < p_from.count; i++) {
 			data[i] = p_from.data[i];
 		}
-		return *this;
 	}
-	inline LocalVector &operator=(const Vector<T> &p_from) {
+	inline void operator=(const Vector<T> &p_from) {
 		resize(p_from.size());
 		for (U i = 0; i < count; i++) {
 			data[i] = p_from[i];
 		}
-		return *this;
 	}
 
 	_FORCE_INLINE_ ~LocalVector() {
diff --git a/core/templates/oa_hash_map.h b/core/templates/oa_hash_map.h
index 025cc30db4..9dab36e343 100644
--- a/core/templates/oa_hash_map.h
+++ b/core/templates/oa_hash_map.h
@@ -353,7 +353,7 @@ public:
 		(*this) = p_other;
 	}
 
-	OAHashMap &operator=(const OAHashMap &p_other) {
+	void operator=(const OAHashMap &p_other) {
 		if (capacity != 0) {
 			clear();
 		}
@@ -363,7 +363,6 @@ public:
 		for (Iterator it = p_other.iter(); it.valid; it = p_other.next_iter(it)) {
 			set(*it.key, *it.value);
 		}
-		return *this;
 	}
 
 	OAHashMap(uint32_t p_initial_capacity = 64) {
diff --git a/core/templates/ordered_hash_map.h b/core/templates/ordered_hash_map.h
index 4996b88190..928072bb18 100644
--- a/core/templates/ordered_hash_map.h
+++ b/core/templates/ordered_hash_map.h
@@ -85,11 +85,10 @@ public:
 				next_element(other.next_element) {
 		}
 
-		Element &operator=(const Element &other) {
+		void operator=(const Element &other) {
 			list_element = other.list_element;
 			next_element = other.next_element;
 			prev_element = other.prev_element;
-			return *this;
 		}
 
 		_FORCE_INLINE_ bool operator==(const Element &p_other) const {
@@ -145,9 +144,8 @@ public:
 				list_element(other.list_element) {
 		}
 
-		ConstElement &operator=(const ConstElement &other) {
+		void operator=(const ConstElement &other) {
 			list_element = other.list_element;
-			return *this;
 		}
 
 		ConstElement next() const {
diff --git a/core/templates/vector.h b/core/templates/vector.h
index a955d49101..376d5cbeff 100644
--- a/core/templates/vector.h
+++ b/core/templates/vector.h
@@ -132,9 +132,8 @@ public:
 		insert(i, p_val);
 	}
 
-	inline Vector &operator=(const Vector &p_from) {
+	inline void operator=(const Vector &p_from) {
 		_cowdata._ref(p_from._cowdata);
-		return *this;
 	}
 
 	Vector<uint8_t> to_byte_array() const {
diff --git a/core/templates/vmap.h b/core/templates/vmap.h
index 2aa22f97cf..0ff105ccbf 100644
--- a/core/templates/vmap.h
+++ b/core/templates/vmap.h
@@ -193,9 +193,8 @@ public:
 	_FORCE_INLINE_ VMap() {}
 	_FORCE_INLINE_ VMap(const VMap &p_from) { _cowdata._ref(p_from._cowdata); }
 
-	inline VMap &operator=(const VMap &p_from) {
+	inline void operator=(const VMap &p_from) {
 		_cowdata._ref(p_from._cowdata);
-		return *this;
 	}
 };