test

project(libconfplus)

cmake_minimum_required(VERSION 3.10)

list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")

project(libconfplus)

set(WINDOWS_EXPORT_ALL_SYMBOLS ON)

# CMake strategy to find the C library libyaml using ONLY the classic search 

# and creating the modern target 'YAML::YAML'.

# CMake strategy to find the C library libyaml using multiple approaches:

# The goal is to set the final target to 'YAML::YAML' in all successful cases.

# --- 1. Classic CMake Search (Manual Fallback) ---

# 1. CONFIG Package Search (e.g., vcpkg, Conan)

# Check for both 'yaml' (common vcpkg) and 'LibYAML' (sometimes provided by system)

find_package(yaml CONFIG QUIET)

find_package(LibYAML CONFIG QUIET)

# Determine if the CONFIG search succeeded

if(YAML_FOUND OR LibYAML_FOUND)

    message(STATUS "Found libyaml via CONFIG.")

    # --- ENSURE UPPERCASE ALIAS ---

    # Most vcpkg/Conan config files define 'yaml::yaml' (lowercase).

    # We must ensure the required 'YAML::YAML' (uppercase) target exists.

    # 1. If the lowercase target exists, create the uppercase alias

    if(TARGET yaml::yaml AND NOT TARGET YAML::YAML)

        add_library(YAML::YAML ALIAS yaml::yaml)

        message(STATUS "Created ALIAS target YAML::YAML -> yaml::yaml.")

    # 2. Check if the uppercase target already exists (e.g., from LibYAML config)

    elseif(TARGET LibYAML::LibYAML AND NOT TARGET YAML::YAML)

        add_library(YAML::YAML ALIAS LibYAML::LibYAML)

        message(STATUS "Created ALIAS target YAML::YAML -> LibYAML::LibYAML.")

    # 3. Handle the case where the CONFIG script already defined YAML::YAML

    elseif(TARGET YAML::YAML)

        # Target already exists, no action needed.

    else()

        message(FATAL_ERROR "libyaml found via CONFIG, but no recognizable target (yaml::yaml or YAML::YAML) was created.")

    endif()

# Fallback to Manual Search

else() 

    # 2. pkg-config Search (Common on Linux/MSYS)

    find_package(PkgConfig QUIET)

    if(PkgConfig_FOUND)

        pkg_check_modules(LIBYAML QUIET yaml-0.1)

    endif()

    # Determine if a manual search is necessary

    if(NOT LIBYAML_FOUND)

        # 3. Classic CMake Search (Manual Fallback)

        find_path(LIBYAML_INCLUDE_DIR yaml.h

                     HINTS $ENV{LIBYAML_ROOT} ${CMAKE_PREFIX_PATH}

                     PATH_SUFFIXES include

                     )

        # Note: 'HINTS ... "${CMAKE_PREFIX_PATH}"' is redundant with PATH_SUFFIXES 'lib' and CMAKE_PREFIX_PATH

        find_library(LIBYAML_LIBRARY NAMES yaml libyaml

                     HINTS $ENV{LIBYAML_ROOT} ${CMAKE_PREFIX_PATH} 

                     PATH_SUFFIXES lib

                     )

# --- 2. Check Results and Set Required Variables ---

if(LIBYAML_INCLUDE_DIR AND LIBYAML_LIBRARY)

    message(STATUS "Found libyaml (C) headers: ${LIBYAML_INCLUDE_DIR}")

    message(STATUS "Found libyaml (C) library: ${LIBYAML_LIBRARY}")

        # 4. Check results from the classic search

        if(NOT (LIBYAML_INCLUDE_DIR AND LIBYAML_LIBRARY))

            message(FATAL_ERROR "libyaml (C) not found. Please set LIBYAML_ROOT or install it.")

        endif()

    endif()

    # --- UNIFIED TARGET CREATION (For pkg-config and Classic) ---

    # This block runs only if we successfully found it manually or via pkg-config

    # --- 3. EXPORT Modern CMake Target ---

    if(NOT TARGET YAML::YAML)

        # Create an INTERFACE IMPORTED target for modern linking

    # 5. Create the final modern target 'YAML::YAML' (Uppercase)

    if(NOT TARGET YAML::YAML) # Only create if not already handled by CONFIG (unlikely here, but safe)

        add_library(YAML::YAML INTERFACE IMPORTED) 

        # Set the properties for the modern target

        if(LIBYAML_FOUND) # pkg-config results

            target_include_directories(YAML::YAML INTERFACE ${LIBYAML_INCLUDE_DIRS})

            target_link_libraries(YAML::YAML INTERFACE ${LIBYAML_LIBRARIES})

        else() # Classic Search results

            target_include_directories(YAML::YAML INTERFACE ${LIBYAML_INCLUDE_DIR})

            target_link_libraries(YAML::YAML INTERFACE ${LIBYAML_LIBRARY})

        message(STATUS "SUCCESS: Created modern IMPORTED target YAML::YAML.")

        endif()

    # Define YAML_FOUND for use outside this script (if needed by other Find modules)

    set(YAML_FOUND TRUE CACHE BOOL "libyaml C library found." FORCE)

# --- 4. Failure Condition ---

else()

    # Check if the variables are set to notify the user what is missing

    if(NOT LIBYAML_INCLUDE_DIR)

        message(STATUS "libyaml header (yaml.h) NOT found.")

    endif()

    if(NOT LIBYAML_LIBRARY)

        message(STATUS "libyaml library NOT found.")

endif()

    # FATAL_ERROR only if necessary

    message(FATAL_ERROR "libyaml (C) not found. Please set LIBYAML_ROOT or ensure files are in CMAKE_PREFIX_PATH.")

endif()

# In your custom FindYAML logic, *immediately* after find_package(yaml CONFIG QUIET)

if(YAML_FOUND)

    # Check if the CONFIG file created the lowercase target

    if(TARGET yaml::yaml AND NOT TARGET YAML::YAML)

        # Create the ALIAS that backends/CMakeLists.txt needs

        add_library(YAML::YAML ALIAS yaml::yaml) 

        message(STATUS "SUCCESS: Created ALIAS target YAML::YAML -> yaml::yaml.")

# The final goal in your consuming CMakeLists.txt:

# target_link_libraries(yamlconf PRIVATE YAML::YAML)

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    # ... (Other checks for LibYAML::LibYAML, etc.) ...

    elseif(NOT TARGET YAML::YAML)

        # If the CONFIG search found the package but didn't create a target we recognize, 

        # the build will fail. Log this for debugging.

        message(WARNING "libyaml found via CONFIG, but failed to create or find target YAML::YAML.")

    endif()

else

    message(FATAL_ERROR "yaml not found")

endif()

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