net/IPv[46]Address: make the initializers more portable

Thanks to C++14, we can declare and fill variables inside `constexpr`
functions.  This means me can stop make assumptions on the `struct`
layouts without losing `constexpr`.

Closes #393

NEWS

@@ -2,6 +2,7 @@ ver 0.21.1 (not yet released)
 * decoder
   - ffmpeg: fix build failure with non-standard FFmpeg installation path
 * fix build failure on Linux-PowerPC
+* fix build failure on FreeBSD
 
 ver 0.21 (2018/10/31)
 * configuration

src/net/IPv4Address.hxx

@@ -53,20 +53,6 @@ class IPv4Address {
 							uint8_t c, uint8_t d) noexcept {
 		return {{{ a, b, c, d }}};
 	}
-
-	/**
-	 * @param x the 32 bit IP address in network byte order
-	 */
-	static constexpr struct in_addr ConstructInAddrBE(uint32_t x) noexcept {
-		return (struct in_addr){{.S_addr=x}};
-	}
-
-	/**
-	 * @param x the 32 bit IP address in host byte order
-	 */
-	static constexpr struct in_addr ConstructInAddr(uint32_t x) noexcept {
-		return ConstructInAddr(x >> 24, x >> 16, x >> 8, x);
-	}
 #else
 
 #ifdef __BIONIC__
@@ -78,11 +64,19 @@ class IPv4Address {
 		return ToBE32((a << 24) | (b << 16) | (c << 8) | d);
 	}
 
+	static constexpr struct in_addr ConstructInAddr(uint8_t a, uint8_t b,
+							uint8_t c, uint8_t d) noexcept {
+		return { ConstructInAddrT(a, b, c, d) };
+	}
+#endif
+
 	/**
 	 * @param x the 32 bit IP address in network byte order
 	 */
 	static constexpr struct in_addr ConstructInAddrBE(uint32_t x) noexcept {
-		return { x };
+		struct in_addr ia{};
+		ia.s_addr = x;
+		return ia;
 	}
 
 	/**
@@ -92,26 +86,16 @@ class IPv4Address {
 		return ConstructInAddrBE(ToBE32(x));
 	}
 
-	static constexpr struct in_addr ConstructInAddr(uint8_t a, uint8_t b,
-							uint8_t c, uint8_t d) noexcept {
-		return { ConstructInAddrT(a, b, c, d) };
-	}
-#endif
-
 	/**
 	 * @param port the port number in host byte order
 	 */
 	static constexpr struct sockaddr_in Construct(struct in_addr address,
 						      uint16_t port) noexcept {
-		return {
-#ifdef HAVE_STRUCT_SOCKADDR_IN_SIN_LEN
-			sizeof(struct sockaddr_in),
-#endif
-			AF_INET,
-			ToBE16(port),
-			address,
-			{},
-		};
+		struct sockaddr_in sin{};
+		sin.sin_family = AF_INET;
+		sin.sin_port = ToBE16(port);
+		sin.sin_addr = address;
+		return sin;
 	}
 
 	/**

src/net/IPv6Address.hxx

@@ -68,16 +68,12 @@ class IPv6Address {
 	static constexpr struct sockaddr_in6 Construct(struct in6_addr address,
 						       uint16_t port,
 						       uint32_t scope_id) noexcept {
-		return {
-#if defined(__APPLE__)
-			sizeof(struct sockaddr_in6),
-#endif
-			AF_INET6,
-			ToBE16(port),
-			0,
-			address,
-			scope_id,
-		};
+		struct sockaddr_in6 sin{};
+		sin.sin6_family = AF_INET6;
+		sin.sin6_port = ToBE16(port);
+		sin.sin6_addr = address;
+		sin.sin6_scope_id = scope_id;
+		return sin;
 	}
 
 public:

src/net/meson.build

@@ -10,14 +10,6 @@ if have_tcp and not get_option('ipv6').disabled()
   if not have_ipv6 and get_option('ipv6').enabled()
     error('IPv6 not supported by OS')
   endif
-
-  conf.set('HAVE_STRUCT_SOCKADDR_IN_SIN_LEN', c_compiler.has_member('struct sockaddr_in', 'sin_len', prefix: '''
-#ifdef _WIN32
-#include <winsock2.h>
-#include <ws2tcpip.h>
-#else
-#include <netinet/in.h>
-#endif'''))
 else
   have_ipv6 = false
 endif