Added more exception safety to Deque::grow

flow/Deque.cpp

@@ -79,4 +79,41 @@ TEST_CASE("/flow/Deque/max_size") {
 	return Void();
 }
 
+struct RandomlyThrows {
+	int data = 0;
+	RandomlyThrows() = default;
+	explicit RandomlyThrows(int data) : data(data) {}
+	~RandomlyThrows() = default;
+	RandomlyThrows(const RandomlyThrows& other) : data(other.data) { randomlyThrow(); }
+	RandomlyThrows& operator=(const RandomlyThrows& other) {
+		data = other.data;
+		randomlyThrow();
+		return *this;
+	}
+
+private:
+	void randomlyThrow() {
+		if (deterministicRandom()->random01() < 0.1) {
+			throw success();
+		}
+	}
+};
+
+TEST_CASE("/flow/Deque/grow_exception_safety") {
+	Deque<RandomlyThrows> q;
+	for (int i = 0; i < 100; ++i) {
+		loop {
+			try {
+				q.push_back(RandomlyThrows{ i });
+				break;
+			} catch (Error& e) {
+			}
+		}
+	}
+	for (int i = 0; i < 100; ++i) {
+		ASSERT(q[i].data == i);
+	}
+	return Void();
+}
+
 void forceLinkDequeTests() {}

flow/Deque.h

@@ -170,8 +170,15 @@ private:
 		T* newArr = (T*)aligned_alloc(std::max(__alignof(T), sizeof(void*)),
 		                              newSize * sizeof(T)); // SOMEDAY: FastAllocator
 		ASSERT(newArr != nullptr);
+		try {
+			for (int i = begin; i != end; i++) {
+				new (&newArr[i - begin]) T(std::move_if_noexcept(arr[i & mask]));
+			}
+		} catch (...) {
+			aligned_free(newArr);
+			throw;
+		}
 		for (int i = begin; i != end; i++) {
-			new (&newArr[i - begin]) T(std::move_if_noexcept(arr[i & mask]));
 			static_assert(std::is_nothrow_destructible_v<T>);
 			arr[i&mask].~T();
 		}