如果遇到報錯
ADD_LIBRARY cannot create target "paho-mqtt3c" because another target with the same name already exists. The existing target is a shared library created in source directory
需要更改
..\paho.mqtt.c\src
下的CMakeLists.txt，將 -static后綴添加到文件中的靜態庫名稱上，有兩個地方需要進行此更改，在該文件中搜索PAHO_BUILD_STATIC：
第94行附近（添加-static到if語句中引用的庫名稱中）：
IF (PAHO_BUILD_STATIC)
ADD_LIBRARY(paho-mqtt3c-static STATIC $<TARGET_OBJECTS:common_obj> MQTTClient.c)
ADD_LIBRARY(paho-mqtt3a-static STATIC $<TARGET_OBJECTS:common_obj> MQTTAsync.c)
TARGET_LINK_LIBRARIES(paho-mqtt3c-static ${LIBS_SYSTEM})
TARGET_LINK_LIBRARIES(paho-mqtt3a-static ${LIBS_SYSTEM})
INSTALL(TARGETS paho-mqtt3c-static paho-mqtt3a-static
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
ENDIF()
在第164行附近（添加-static到if語句中引用的庫名稱中）：
IF (PAHO_BUILD_STATIC)
ADD_LIBRARY(paho-mqtt3cs-static STATIC $<TARGET_OBJECTS:common_ssl_obj> MQTTClient.c SSLSocket.c)
ADD_LIBRARY(paho-mqtt3as-static STATIC $<TARGET_OBJECTS:common_ssl_obj> MQTTAsync.c SSLSocket.c)
TARGET_LINK_LIBRARIES(paho-mqtt3cs-static ${OPENSSL_LIBRARIES} ${LIBS_SYSTEM})
TARGET_LINK_LIBRARIES(paho-mqtt3as-static ${OPENSSL_LIBRARIES} ${LIBS_SYSTEM})
SET_TARGET_PROPERTIES(
paho-mqtt3cs-static paho-mqtt3as-static PROPERTIES
VERSION ${CLIENT_VERSION}
SOVERSION ${PAHO_VERSION_MAJOR}
COMPILE_DEFINITIONS "OPENSSL=1")
INSTALL(TARGETS paho-mqtt3cs-static paho-mqtt3as-static
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
ENDIF()
進行更改后，清除CMake緩存（或刪除構建文件夾中的CMakeCache.txt文件）並重新運行CMake。