Make classes derived from buffer<T> final to silence the virtual destructor warning. (#1937)

Co-authored-by: Bart Siwek <bsiwek@cisco.com>

include/fmt/core.h

@@ -761,7 +761,7 @@ class fixed_buffer_traits {
 
 // A buffer that writes to an output iterator when flushed.
 template <typename OutputIt, typename T, typename Traits = buffer_traits>
-class iterator_buffer : public Traits, public buffer<T> {
+class iterator_buffer final : public Traits, public buffer<T> {
  private:
   OutputIt out_;
   enum { buffer_size = 256 };
@@ -787,7 +787,7 @@ class iterator_buffer : public Traits, public buffer<T> {
   size_t count() const { return Traits::count() + this->size(); }
 };
 
-template <typename T> class iterator_buffer<T*, T> : public buffer<T> {
+template <typename T> class iterator_buffer<T*, T> final : public buffer<T> {
  protected:
   void grow(size_t) final FMT_OVERRIDE {}
 
@@ -801,7 +801,7 @@ template <typename T> class iterator_buffer<T*, T> : public buffer<T> {
 template <typename Container>
 class iterator_buffer<std::back_insert_iterator<Container>,
                       enable_if_t<is_contiguous<Container>::value,
-                                  typename Container::value_type>>
+                                  typename Container::value_type>> final
     : public buffer<typename Container::value_type> {
  private:
   Container& container_;
@@ -823,7 +823,7 @@ class iterator_buffer<std::back_insert_iterator<Container>,
 };
 
 // A buffer that counts the number of code units written discarding the output.
-template <typename T = char> class counting_buffer : public buffer<T> {
+template <typename T = char> class counting_buffer final : public buffer<T> {
  private:
   enum { buffer_size = 256 };
   T data_[buffer_size];

include/fmt/format.h

@@ -651,7 +651,7 @@ enum { inline_buffer_size = 500 };
  */
 template <typename T, size_t SIZE = inline_buffer_size,
           typename Allocator = std::allocator<T>>
-class basic_memory_buffer : public detail::buffer<T> {
+class basic_memory_buffer final : public detail::buffer<T> {
  private:
   T store_[SIZE];
 

include/fmt/os.h

@@ -378,7 +378,7 @@ struct ostream_params {
 static constexpr detail::buffer_size buffer_size;
 
 // A fast output stream which is not thread-safe.
-class ostream : private detail::buffer<char> {
+class ostream final : private detail::buffer<char> {
  private:
   file file_;
 

test/core-test.cc

@@ -78,7 +78,7 @@ TEST(BufferTest, Indestructible) {
                 "buffer's destructor is protected");
 }
 
-template <typename T> struct mock_buffer : buffer<T> {
+template <typename T> struct mock_buffer final : buffer<T> {
   MOCK_METHOD1(do_grow, size_t(size_t capacity));
 
   void grow(size_t capacity) { this->set(this->data(), do_grow(capacity)); }
@@ -368,7 +368,7 @@ TEST(ArgTest, PointerArg) {
 struct check_custom {
   test_result operator()(
       fmt::basic_format_arg<fmt::format_context>::handle h) const {
-    struct test_buffer : fmt::detail::buffer<char> {
+    struct test_buffer final : fmt::detail::buffer<char> {
       char data[10];
       test_buffer() : fmt::detail::buffer<char>(data, 0, 10) {}
       void grow(size_t) {}

test/format-test.cc

@@ -293,12 +293,8 @@ TEST(MemoryBufferTest, MoveAssignment) {
 
 TEST(MemoryBufferTest, Grow) {
   typedef allocator_ref<mock_allocator<int>> Allocator;
-  typedef basic_memory_buffer<int, 10, Allocator> Base;
   mock_allocator<int> alloc;
-  struct TestMemoryBuffer : Base {
+  basic_memory_buffer<int, 10, Allocator> buffer((Allocator(&alloc)));
-    TestMemoryBuffer(Allocator alloc) : Base(alloc) {}
-    using Base::grow;
-  } buffer((Allocator(&alloc)));
   buffer.resize(7);
   using fmt::detail::to_unsigned;
   for (int i = 0; i < 7; ++i) buffer[to_unsigned(i)] = i * i;
@@ -306,7 +302,7 @@ TEST(MemoryBufferTest, Grow) {
   int mem[20];
   mem[7] = 0xdead;
   EXPECT_CALL(alloc, allocate(20)).WillOnce(Return(mem));
-  buffer.grow(20);
+  buffer.try_reserve(20);
   EXPECT_EQ(20u, buffer.capacity());
   // Check if size elements have been copied
   for (int i = 0; i < 7; ++i) EXPECT_EQ(i * i, buffer[to_unsigned(i)]);

test/ostream-test.cc

@@ -150,7 +150,7 @@ TEST(OStreamTest, WriteToOStreamMaxSize) {
   std::streamsize max_streamsize = fmt::detail::max_value<std::streamsize>();
   if (max_size <= fmt::detail::to_unsigned(max_streamsize)) return;
 
-  struct test_buffer : fmt::detail::buffer<char> {
+  struct test_buffer final : fmt::detail::buffer<char> {
     explicit test_buffer(size_t size)
       : fmt::detail::buffer<char>(nullptr, size, size) {}
     void grow(size_t) {}