Fix build on Embarcadero C++Builder 10.3

Double braces aren't necessary for list-initialization after a '=' sign.
  - https://en.cppreference.com/w/cpp/container/array#Example
  - https://www.boost.org/doc/libs/1_69_0/doc/html/array/rationale.html

In Embarcadero C++Builder 10.3 (`bcc32c`) that syntax fails to compile.
Change to single braces.

Also allow `BOOST_ASIO_HAS_HANDLER_HOOKS` to be enabled on the modern
[Clang-based](http://docwiki.embarcadero.com/RADStudio/Rio/en/Win32_Clang-enhanced_Compilers)
C++Builder compilers.

example/cpp03/icmp/ipv4_header.hpp

@@ -68,14 +68,14 @@ class ipv4_header
   boost::asio::ip::address_v4 source_address() const
   {
     boost::asio::ip::address_v4::bytes_type bytes
-      = { { rep_[12], rep_[13], rep_[14], rep_[15] } };
+      = { rep_[12], rep_[13], rep_[14], rep_[15] };
     return boost::asio::ip::address_v4(bytes);
   }
 
   boost::asio::ip::address_v4 destination_address() const
   {
     boost::asio::ip::address_v4::bytes_type bytes
-      = { { rep_[16], rep_[17], rep_[18], rep_[19] } };
+      = { rep_[16], rep_[17], rep_[18], rep_[19] };
     return boost::asio::ip::address_v4(bytes);
   }
 

example/cpp03/porthopper/protocol.hpp

@@ -72,7 +72,7 @@ class control_request
   boost::array<boost::asio::mutable_buffer, 1> to_buffers()
   {
     boost::array<boost::asio::mutable_buffer, 1> buffers
-      = { { boost::asio::buffer(data_) } };
+      = { boost::asio::buffer(data_) };
     return buffers;
   }
 
@@ -137,7 +137,7 @@ class frame
   boost::array<boost::asio::mutable_buffer, 1> to_buffers()
   {
     boost::array<boost::asio::mutable_buffer, 1> buffers
-      = { { boost::asio::buffer(data_) } };
+      = { boost::asio::buffer(data_) };
     return buffers;
   }
 

include/boost/asio/detail/config.hpp

@@ -1334,9 +1334,9 @@
 #   if (__GNUC__ >= 3)
 #    define BOOST_ASIO_HAS_HANDLER_HOOKS 1
 #   endif // (__GNUC__ >= 3)
-#  elif !defined(__BORLANDC__)
+#  elif !defined(__BORLANDC__) || defined(__clang__)
 #   define BOOST_ASIO_HAS_HANDLER_HOOKS 1
-#  endif // !defined(__BORLANDC__)
+#  endif // !defined(__BORLANDC__) || defined(__clang__)
 # endif // !defined(BOOST_ASIO_DISABLE_HANDLER_HOOKS)
 #endif // !defined(BOOST_ASIO_HAS_HANDLER_HOOKS)
 

include/boost/asio/detail/impl/dev_poll_reactor.ipp

@@ -285,7 +285,7 @@ void dev_poll_reactor::run(long usec, op_queue<operation>& ops)
   lock.unlock();
 
   // Block on the /dev/poll descriptor.
-  ::pollfd events[128] = { { 0, 0, 0 } };
+  ::pollfd events[128] = { 0, 0, 0 };
   ::dvpoll dp = { 0, 0, 0 };
   dp.dp_fds = events;
   dp.dp_nfds = 128;

include/boost/asio/ip/impl/address_v6.ipp

@@ -133,8 +133,8 @@ address_v4 address_v6::to_v4() const
     boost::asio::detail::throw_exception(ex);
   }
 
-  address_v4::bytes_type v4_bytes = { { addr_.s6_addr[12],
-    addr_.s6_addr[13], addr_.s6_addr[14], addr_.s6_addr[15] } };
+  address_v4::bytes_type v4_bytes = { addr_.s6_addr[12],
+    addr_.s6_addr[13], addr_.s6_addr[14], addr_.s6_addr[15] };
   return address_v4(v4_bytes);
 }
 #endif // !defined(BOOST_ASIO_NO_DEPRECATED)
@@ -260,16 +260,16 @@ address_v6 address_v6::loopback() BOOST_ASIO_NOEXCEPT
 address_v6 address_v6::v4_mapped(const address_v4& addr)
 {
   address_v4::bytes_type v4_bytes = addr.to_bytes();
-  bytes_type v6_bytes = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF,
-    v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] } };
+  bytes_type v6_bytes = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF,
+    v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] };
   return address_v6(v6_bytes);
 }
 
 address_v6 address_v6::v4_compatible(const address_v4& addr)
 {
   address_v4::bytes_type v4_bytes = addr.to_bytes();
-  bytes_type v6_bytes = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] } };
+  bytes_type v6_bytes = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] };
   return address_v6(v6_bytes);
 }
 #endif // !defined(BOOST_ASIO_NO_DEPRECATED)
@@ -329,17 +329,17 @@ address_v4 make_address_v4(
   }
 
   address_v6::bytes_type v6_bytes = v6_addr.to_bytes();
-  address_v4::bytes_type v4_bytes = { { v6_bytes[12],
-    v6_bytes[13], v6_bytes[14], v6_bytes[15] } };
+  address_v4::bytes_type v4_bytes = { v6_bytes[12],
+    v6_bytes[13], v6_bytes[14], v6_bytes[15] };
   return address_v4(v4_bytes);
 }
 
 address_v6 make_address_v6(
     v4_mapped_t, const address_v4& v4_addr)
 {
   address_v4::bytes_type v4_bytes = v4_addr.to_bytes();
-  address_v6::bytes_type v6_bytes = { { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-    0xFF, 0xFF, v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] } };
+  address_v6::bytes_type v6_bytes = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0xFF, 0xFF, v4_bytes[0], v4_bytes[1], v4_bytes[2], v4_bytes[3] };
   return address_v6(v6_bytes);
 }
 

test/buffer.cpp

@@ -48,12 +48,12 @@ void test()
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
     boost::array<char, 1024> array_data;
     const boost::array<char, 1024>& const_array_data_1 = array_data;
-    boost::array<const char, 1024> const_array_data_2 = { { 0 } };
+    boost::array<const char, 1024> const_array_data_2 = { 0 };
 #endif // defined(BOOST_ASIO_HAS_BOOST_ARRAY)
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
     std::array<char, 1024> std_array_data;
     const std::array<char, 1024>& const_std_array_data_1 = std_array_data;
-    std::array<const char, 1024> const_std_array_data_2 = { { 0 } };
+    std::array<const char, 1024> const_std_array_data_2 = { 0 };
 #endif // defined(BOOST_ASIO_HAS_STD_ARRAY)
     std::vector<char> vector_data(1024);
     const std::vector<char>& const_vector_data = vector_data;

test/ip/address_v4.cpp

@@ -40,7 +40,7 @@ void test()
     // address_v4 constructors.
 
     ip::address_v4 addr1;
-    const ip::address_v4::bytes_type const_bytes_value = { { 127, 0, 0, 1 } };
+    const ip::address_v4::bytes_type const_bytes_value = { 127, 0, 0, 1 };
     ip::address_v4 addr2(const_bytes_value);
     const unsigned long const_ulong_value = 0x7F000001;
     ip::address_v4 addr3(const_ulong_value);

test/ip/address_v6.cpp

@@ -40,7 +40,7 @@ void test()
     // address_v6 constructors.
 
     ip::address_v6 addr1;
-    const ip::address_v6::bytes_type const_bytes_value = { { 0 } };
+    const ip::address_v6::bytes_type const_bytes_value = { 0 };
     ip::address_v6 addr2(const_bytes_value);
 
     // address_v6 functions.

test/read.cpp

@@ -2547,9 +2547,9 @@ void test_3_arg_boost_array_buffers_async_read()
   boost::asio::io_context ioc;
   test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::array<boost::asio::mutable_buffer, 2> buffers = { {
+  boost::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -2610,9 +2610,9 @@ void test_3_arg_std_array_buffers_async_read()
   boost::asio::io_context ioc;
   test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  std::array<boost::asio::mutable_buffer, 2> buffers = { {
+  std::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -3205,9 +3205,9 @@ void test_4_arg_boost_array_buffers_async_read()
   boost::asio::io_context ioc;
   test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::array<boost::asio::mutable_buffer, 2> buffers = { {
+  boost::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -3549,9 +3549,9 @@ void test_4_arg_std_array_buffers_async_read()
   boost::asio::io_context ioc;
   test_stream s(ioc);
   char read_buf[sizeof(read_data)];
-  std::array<boost::asio::mutable_buffer, 2> buffers = { {
+  std::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));

test/read_at.cpp

@@ -3544,9 +3544,9 @@ void test_4_arg_boost_array_buffers_async_read_at()
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::array<boost::asio::mutable_buffer, 2> buffers = { {
+  boost::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -3643,9 +3643,9 @@ void test_4_arg_std_array_buffers_async_read_at()
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  std::array<boost::asio::mutable_buffer, 2> buffers = { {
+  std::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -4637,9 +4637,9 @@ void test_5_arg_boost_array_buffers_async_read_at()
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  boost::array<boost::asio::mutable_buffer, 2> buffers = { {
+  boost::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));
@@ -5338,9 +5338,9 @@ void test_5_arg_std_array_buffers_async_read_at()
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
   char read_buf[sizeof(read_data)];
-  std::array<boost::asio::mutable_buffer, 2> buffers = { {
+  std::array<boost::asio::mutable_buffer, 2> buffers = {
     boost::asio::buffer(read_buf, 32),
-    boost::asio::buffer(read_buf) + 32 } };
+    boost::asio::buffer(read_buf) + 32 };
 
   s.reset(read_data, sizeof(read_data));
   memset(read_buf, 0, sizeof(read_buf));

test/write.cpp

@@ -2294,9 +2294,9 @@ void test_3_arg_boost_array_buffers_async_write()
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
   boost::asio::io_context ioc;
   test_stream s(ioc);
-  boost::array<boost::asio::const_buffer, 2> buffers = { {
+  boost::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;
@@ -2352,9 +2352,9 @@ void test_3_arg_std_array_buffers_async_write()
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
   boost::asio::io_context ioc;
   test_stream s(ioc);
-  std::array<boost::asio::const_buffer, 2> buffers = { {
+  std::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;
@@ -3220,9 +3220,9 @@ void test_4_arg_boost_array_buffers_async_write()
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
   boost::asio::io_context ioc;
   test_stream s(ioc);
-  boost::array<boost::asio::const_buffer, 2> buffers = { {
+  boost::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;
@@ -3535,9 +3535,9 @@ void test_4_arg_std_array_buffers_async_write()
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
   boost::asio::io_context ioc;
   test_stream s(ioc);
-  std::array<boost::asio::const_buffer, 2> buffers = { {
+  std::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;

test/write_at.cpp

@@ -3156,9 +3156,9 @@ void test_4_arg_boost_array_buffers_async_write_at()
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
-  boost::array<boost::asio::const_buffer, 2> buffers = { {
+  boost::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;
@@ -3258,9 +3258,9 @@ void test_4_arg_std_array_buffers_async_write_at()
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
-  std::array<boost::asio::const_buffer, 2> buffers = { {
+  std::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;
@@ -4860,9 +4860,9 @@ void test_5_arg_boost_array_buffers_async_write_at()
 #if defined(BOOST_ASIO_HAS_BOOST_ARRAY)
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
-  boost::array<boost::asio::const_buffer, 2> buffers = { {
+  boost::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;
@@ -5505,9 +5505,9 @@ void test_5_arg_std_array_buffers_async_write_at()
 #if defined(BOOST_ASIO_HAS_STD_ARRAY)
   boost::asio::io_context ioc;
   test_random_access_device s(ioc);
-  std::array<boost::asio::const_buffer, 2> buffers = { {
+  std::array<boost::asio::const_buffer, 2> buffers = {
     boost::asio::buffer(write_data, 32),
-    boost::asio::buffer(write_data) + 32 } };
+    boost::asio::buffer(write_data) + 32 };
 
   s.reset();
   bool called = false;