I’m trying to run my Native C++ project on Android Studio and i need to compile my C++ part using cmake.

I need to use this repository for reading json:

https://github.com/nlohmann/json

NOTE: Using it with this command is not my intention and I cannot use this solution:

find_package(nlohmann_json 3.11.3 REQUIRED)

I have to use the whole repo code in my project.

My problem is that when I try to build it I get the follwing error:

C:/Users/XXXXXXXXXX/AndroidStudioProjects/nav/app/src/main/cpp/nlohmann/json.hpp:34:10:fatal error: 'nlohmann/adl_serializer.hpp' file not found #include <nlohmann/adl_serializer.hpp>

The adl_serializer.hpp file is there 100%. The problem is that i call this include from nlohmann/json.hpp which already is in the nlohmann directory and therefore I think it is looking for something like nlohmann/nlohmann/adl_serializer.hpp.

I already tried to update my cmake:

cmake_minimum_required(VERSION 3.22.1)
project(nav)

set(djinni_dir ../../../../djinni)
# Path to djinni support-lib code
set(support_dir ${djinni_dir}/djinni-support-lib/djinni/jni)
# Path to Djinni-generated files
set(DJINNI_GENERATED_SRC_DIR "${CMAKE_SOURCE_DIR}/../../")
# Path to the nlohmann directory for JSON read
set(NLOHMANN_INCLUDE_DIR "${CMAKE_SOURCE_DIR}/nlohmann")
# Path to the generated code and our own c++ implementations
set(include_dirs
        ${DJINNI_GENERATED_SRC_DIR}/cpp
        ${DJINNI_GENERATED_SRC_DIR}/jni
        ${NLOHMANN_INCLUDE_DIR}
)

# Djinni support code that need to be compiled
file(
        GLOB_RECURSE support_srcs
        ${support_dir}/*.cpp)

# Collect all generated and source files
file(GLOB_RECURSE lib_srcs
        ${DJINNI_GENERATED_SRC_DIR}/cpp/*.cpp
        ${DJINNI_GENERATED_SRC_DIR}/jni/*.cpp
)

# All the implementation files that make up our library
set(complete_srcs ${support_srcs} ${lib_srcs})

add_library( # Sets the name of the library.
        navigator

        # Sets the library as a shared library.
        SHARED

        # Provides a relative path to your source file(s).
        native-lib.cpp
        nav.cpp

        ${complete_srcs})

target_include_directories(
        navigator
        PUBLIC
        ${include_dirs}
        ${support_dir})

find_library( # Sets the name of the path variable.
        log-lib
        # Specifies the name of the NDK library that
        # you want CMake to locate.
        log)

target_link_libraries( # Specifies the target library.
        navigator
        # Links the target library to the log library
        # included in the NDK.
        ${log-lib})

and tried changing this line:

set(NLOHMANN_INCLUDE_DIR "${CMAKE_SOURCE_DIR}/nlohmann")

for that:

set(NLOHMANN_INCLUDE_DIR "${CMAKE_SOURCE_DIR}")

But it doesn’t solve my case.

Another issue is that I probably shouldn’t use <> instead of “” around #includes, but changing this now didn’t solve my problem as well.