libcryfs/vendor/cryptopp/CMakeLists.txt

project(mycryptopp)

add_library(cryptopp INTERFACE)
# note: include directory is called vendor_cryptopp instead of cryptopp to avoid include clashes with system headers
target_include_directories(cryptopp SYSTEM INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})

# Forward debug build info (i.e. set CRYPTOPP_DEBUG variable if building in debug mode)
target_compile_definitions(cryptopp INTERFACE $<$<CONFIG:Debug>:CRYPTOPP_DEBUG>) # add to all targets depending on this
add_compile_options($<$<CONFIG:Debug>:-DCRYPTOPP_DEBUG>) # add to stuff built in subdirectories (like the actual library)

if(NOT DISABLE_OPENMP)
    find_package(OpenMP)

    if (OPENMP_FOUND OR OPENMP_CXX_FOUND)
        message(STATUS "Found libomp without any special flags")
    endif()

    # If OpenMP wasn't found, try if we can find it in the default Macports location
    if((NOT OPENMP_FOUND) AND (NOT OPENMP_CXX_FOUND) AND EXISTS "/opt/local/lib/libomp/libomp.dylib") # older cmake uses OPENMP_FOUND, newer cmake also sets OPENMP_CXX_FOUND, homebrew installations seem only to get the latter set.
        set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I/opt/local/include/libomp/")
        set(OpenMP_CXX_LIB_NAMES omp)
        set(OpenMP_omp_LIBRARY /opt/local/lib/libomp/libomp.dylib)

        find_package(OpenMP)
        if (OPENMP_FOUND OR OPENMP_CXX_FOUND)
            message(STATUS "Found libomp in macports default location.")
        else()
            message(FATAL_ERROR "Didn't find libomp. Tried macports default location but also didn't find it.")
        endif()
    endif()

    # If OpenMP wasn't found, try if we can find it in the default Homebrew location
    if((NOT OPENMP_FOUND) AND (NOT OPENMP_CXX_FOUND) AND EXISTS "/usr/local/opt/libomp/lib/libomp.dylib")
        set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp -I/usr/local/opt/libomp/include")
        set(OpenMP_CXX_LIB_NAMES omp)
        set(OpenMP_omp_LIBRARY /usr/local/opt/libomp/lib/libomp.dylib)

        find_package(OpenMP)
        if (OPENMP_FOUND OR OPENMP_CXX_FOUND)
            message(STATUS "Found libomp in homebrew default location.")
        else()
            message(FATAL_ERROR "Didn't find libomp. Tried homebrew default location but also didn't find it.")
        endif()
    endif()

    set(Additional_OpenMP_Libraries_Workaround "")

    # Workaround because older cmake on apple doesn't support FindOpenMP
    if((NOT OPENMP_FOUND) AND (NOT OPENMP_CXX_FOUND))
        if((APPLE AND ((CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang") OR (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")))
                AND ((CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "7.0") AND (CMAKE_VERSION VERSION_LESS "3.12.0")))
            message(STATUS "Applying workaround for OSX OpenMP with old cmake that doesn't have FindOpenMP")
            set(OpenMP_CXX_FLAGS "-Xclang -fopenmp")
            set(Additional_OpenMP_Libraries_Workaround "-lomp")
        else()
            message(FATAL_ERROR "Did not find OpenMP. Build with -DDISABLE_OPENMP=ON if you want to allow this and are willing to take the performance hit.")
        endif()
    endif()

    if(NOT TARGET OpenMP::OpenMP_CXX)
        # We're on cmake < 3.9, handle behavior of the old FindOpenMP implementation
        message(STATUS "Applying workaround for old CMake that doesn't define FindOpenMP using targets")
        add_library(OpenMP_TARGET INTERFACE)
        add_library(OpenMP::OpenMP_CXX ALIAS OpenMP_TARGET)
        target_compile_options(OpenMP_TARGET INTERFACE ${OpenMP_CXX_FLAGS}) # add to all targets depending on this
        find_package(Threads REQUIRED)
        target_link_libraries(OpenMP_TARGET INTERFACE Threads::Threads)
        target_link_libraries(OpenMP_TARGET INTERFACE ${OpenMP_CXX_FLAGS} ${Additional_OpenMP_Libraries_Workaround})
    endif()

    target_link_libraries(cryptopp INTERFACE ${OpenMP_CXX_FLAGS}) # Workaround for Ubuntu 18.04 that otherwise doesn't set -fopenmp for linking
    target_link_libraries(cryptopp INTERFACE OpenMP::OpenMP_CXX)

    # also add these flags to the third party Crypto++ build setup that is built in a subdirectory
    message(STATUS "OpenMP flags: ${OpenMP_CXX_FLAGS}")
    string(REPLACE " " ";" REPLACED_FLAGS ${OpenMP_CXX_FLAGS})
    add_compile_options(${REPLACED_FLAGS})
else()
    message(WARNING "OpenMP is disabled. This can cause degraded performance.")
endif()


set(CRYPTOPP_BUILD_TESTING OFF CACHE BOOL "")
set(BUILD_DOCUMENTATION OFF CACHE BOOL "")
set(BUILD_SHARED OFF CACHE BOOL "")
set(BUILD_STATIC ON CACHE BOOL "")
set(cryptocpp_DISPLAY_CMAKE_SUPPORT_WARNING OFF CACHE BOOL "")
add_subdirectory(vendor_cryptopp EXCLUDE_FROM_ALL)

target_link_libraries(cryptopp INTERFACE cryptopp-static)