I have an application that uses multiple libraries imported/compiled via VCPKG. The project is then build with cmake with C++14 using set(CMAKE_CXX_STANDARD 14) since Activemq-cpp cannot be built with higher cpp versions.

My question is, is it possible to tell vcpkg/cmake to build (or link ?) activemq-cpp using C++14 and then set the C++ version of the final project to C++20 ?

I’m quite new to CMake so this is a bit confusing to me.

Here are the files:

vcpkg.json

{
  "dependencies": [
    {
      "name": "opencascade",
      "version>=": "7.8.1"
    },
    {
      "name": "protobuf",
      "version>=": "3.21.8"
    },
    {
      "name": "activemq-cpp",
      "version>=": "3.9.5#15"
    }
  ],
  "version-string": "0.13.1",
  "name": "opencascade-rendering-viewer"
}

CMakeList.txt

# --- General CMake settings -------------------------------------------
cmake_minimum_required(VERSION 3.21 FATAL_ERROR)


set(PROJECT_NAME "OpenCASCADE_Rendering_Server")
set(PROJECT_VERSION "0.13.1")
message(STATUS "Project Name: ${PROJECT_NAME} | Version: ${PROJECT_VERSION}")

project(${PROJECT_NAME} LANGUAGES CXX VERSION ${PROJECT_VERSION})

# Note from 26/07/2024
# This project uses Activemq-CPP, which cannot be build with c++ versions above 14 currently.
set(CMAKE_CXX_STANDARD 14)


# --- C++ Preprocessor Definitions --------------------------------------
add_compile_definitions($<$<CONFIG:DEBUG>:_DEBUG> $<$<NOT:$<CONFIG:DEBUG>>:NDEBUG>)
if (CMAKE_HOST_WIN32)
    add_compile_definitions(WIN32)
elseif (CMAKE_HOST_UNIX)
    add_compile_definitions(UNIX)
endif (CMAKE_HOST_WIN32)


# --- Packages ----------------------------------------------------------
find_package(OpenCASCADE CONFIG REQUIRED)

find_package(Protobuf CONFIG REQUIRED)

find_package(activemq-cpp CONFIG REQUIRED)


# --- Add custom CMake modules ------------------------------------------
include(cmake/protobufcompile.cmake)


# --- Add source files & Executable -------------------------------------
list(APPEND SRC /* Application .cpp files */)

list(APPEND HDR /* Application .h files */)

configure_file(config.h.in ${CMAKE_CURRENT_SOURCE_DIR}/src/config.h @ONLY)
add_executable(${PROJECT_NAME} ${SRC} ${HDR} ${PROTOBUF_GENERATED_FILES})

# --- Add include directories -------------------------------------------
target_include_directories(${PROJECT_NAME} PRIVATE src)


# --- Add external libraries main executable ----------------------------
target_link_libraries(${PROJECT_NAME} PRIVATE ${OpenCASCADE_LIBRARIES})
target_include_directories(${PROJECT_NAME} SYSTEM PRIVATE ${OpenCASCADE_INCLUDE_DIR})

target_link_libraries(${PROJECT_NAME} PRIVATE protobuf::libprotoc protobuf::libprotobuf protobuf::libprotobuf-lite)
target_include_directories(${PROJECT_NAME} SYSTEM PRIVATE ${PROTOBUF_COMPILER_CPP_OUT})

target_link_libraries(${PROJECT_NAME} PRIVATE unofficial::activemq-cpp::apr unofficial::activemq-cpp::activemq-cpp)
if (CMAKE_HOST_WIN32)
    target_link_libraries(${PROJECT_NAME} PRIVATE unofficial::activemq-cpp::ws2 unofficial::activemq-cpp::rpcrt4 unofficial::activemq-cpp::mswsock)
endif (CMAKE_HOST_WIN32)