Compile does not find yaml.h include file with Macports on Mac

[DavidSagan]

Error message:

(base) MAC:~/BmadBase/pals-cpp/build> make
[ 25%] Building CXX object CMakeFiles/yaml_c_wrapper.dir/src/yaml_c_wrapper.cpp.o
/Users/dcs16/BmadBase/pals-cpp/src/yaml_c_wrapper.cpp:1:10: fatal error: 'yaml-cpp/yaml.h' file not found
    1 | #include <yaml-cpp/yaml.h>
      |          ^~~~~~~~~~~~~~~~~
1 error generated.
make[2]: *** [CMakeFiles/yaml_c_wrapper.dir/src/yaml_c_wrapper.cpp.o] Error 1
make[1]: *** [CMakeFiles/yaml_c_wrapper.dir/all] Error 2
make: *** [all] Error 2

The include file is at

/opt/local/include/yaml-cpp/yaml.h

[DavidSagan]

Claude suggested this for CMakeLists.txt:

cmake_minimum_required(VERSION 3.10)
project(YAMLWrapper)

set(CMAKE_CXX_STANDARD 17)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

if(APPLE)
    # Force MacPorts paths FIRST, before any conda paths
    set(CMAKE_PREFIX_PATH /opt/local)
    set(CMAKE_IGNORE_PATH /Users/dcs16/miniconda3)  # Ignore conda!
    
    set(CMAKE_INSTALL_RPATH "@executable_path/../lib;@loader_path;/opt/local/lib")
    set(CMAKE_BUILD_WITH_INSTALL_RPATH TRUE)
endif()

find_package(yaml-cpp REQUIRED)

add_library(yaml_c_wrapper SHARED src/yaml_c_wrapper.cpp)
target_link_libraries(yaml_c_wrapper yaml-cpp::yaml-cpp)

add_executable(yaml_reader src/yaml_reader.cpp)
target_link_libraries(yaml_reader yaml-cpp::yaml-cpp)

Note that this is not generic! So do not use directly.

[DavidSagan]

The reason for the CMAKE_IGNORE_PATH is that I have a Conda install and the linker was using the Conda libraries instead of the MacPorts one.