On loongson/sparc64/hppa/riscv:
CIpcServerProxy.cpp: In member function 'void CIpcServerProxy::send(const CIpcMessage&)':
CIpcServerProxy.cpp:93: ISO C++ says that these are ambiguous, even though the worst conversion for the first is better than the worst conversion for the second:
../synergy/CProtocolUtil.h:81: note: candidate 1: static void CProtocolUtil::writef(void*, const char*, void*)
../synergy/CProtocolUtil.h:53: note: candidate 2: static void CProtocolUtil::writef(synergy::IStream*, const char*, ...)
../synergy/CProtocolUtil.h:81: error: 'static void CProtocolUtil::writef(void*, const char*, void*)' is private
CIpcServerProxy.cpp:93: error: within this context

gcc bug fixed in 4.3.3 (but similar occurs in clang 11.1.0)

Index: src/lib/ipc/IpcServerProxy.cpp
--- src/lib/ipc/IpcServerProxy.cpp.orig
+++ src/lib/ipc/IpcServerProxy.cpp
@@ -95,7 +95,11 @@ IpcServerProxy::send(const IpcMessage& message)
 	case kIpcCommand: {
 		const IpcCommandMessage& cm = static_cast<const IpcCommandMessage&>(message);
 		String command = cm.command();
+#if defined(__mips64__) || defined(__sparc64__) || defined(__hppa__) || defined(__riscv)
+		ProtocolUtil::writef(static_cast<void*>(&m_stream), static_cast<const char*>(kIpcMsgCommand), &command);
+#else
 		ProtocolUtil::writef(&m_stream, kIpcMsgCommand, &command);
+#endif
 		break;
 	}