urho3d/cmake/Toolchains/MinGW.cmake

# Copyright (c) 2008-2022 the Urho3D project
# License: MIT

# https://cmake.org/cmake/help/book/mastering-cmake/chapter/Cross%20Compiling%20With%20CMake.html

# Workaround try_compile() limitation where it cannot yet see cache variables during initial configuration
get_property (IN_TRY_COMPILE GLOBAL PROPERTY IN_TRY_COMPILE)
if (IN_TRY_COMPILE)
    foreach (VAR $ENV{VARS})
        set (${VAR} $ENV{${VAR}})
    endforeach ()
else ()
    # Prevent critical variables from changing after the initial configuration
    if (CMAKE_CROSSCOMPILING)
        set (SAVED_MINGW_SYSROOT ${MINGW_SYSROOT} CACHE INTERNAL "Initial value for MINGW_SYSROOT")
        set (SAVED_MINGW_PREFIX ${MINGW_PREFIX} CACHE INTERNAL "Initial value for MINGW_PREFIX")
        # Save the initial values of CC and CXX environment variables
        set (SAVED_CC $ENV{CC} CACHE INTERNAL "Initial value for CC")
        set (SAVED_CXX $ENV{CXX} CACHE INTERNAL "Initial value for CXX")
        return ()
    elseif ((SAVED_MINGW_SYSROOT AND NOT SAVED_MINGW_SYSROOT STREQUAL MINGW_SYSROOT) OR (SAVED_MINGW_PREFIX AND NOT SAVED_MINGW_PREFIX STREQUAL MINGW_PREFIX))
        set (MINGW_SYSROOT ${SAVED_MINGW_SYSROOT} CACHE PATH "Path to MinGW system root (MinGW only); should only be used when the system root could not be auto-detected" FORCE)
        set (MINGW_PREFIX ${SAVED_MINGW_PREFIX} CACHE STRING "Prefix path to MinGW cross-compiler tools (MinGW cross-compiling build only)" FORCE)
        message (FATAL_ERROR "MINGW_SYSROOT and MINGW_PREFIX cannot be changed after the initial configuration/generation. "
            "If you wish to change that then the build tree would have to be regenerated from scratch. Auto reverting to its initial value.")
    endif ()
endif ()

# Reference toolchain variable to suppress "unused variable" warning
if (CMAKE_TOOLCHAIN_FILE)
    mark_as_advanced (CMAKE_TOOLCHAIN_FILE)
endif ()

# This one is important
set (CMAKE_SYSTEM_NAME Windows)
# This one not so much
set (CMAKE_SYSTEM_PROCESSOR x86)
set (CMAKE_SYSTEM_VERSION 1)

# Cross compiler tools
if (NOT IN_TRY_COMPILE AND NOT SAVED_MINGW_PREFIX)
    if (NOT MINGW_PREFIX AND DEFINED ENV{MINGW_PREFIX})
        file (TO_CMAKE_PATH $ENV{MINGW_PREFIX} MINGW_PREFIX)
    endif ()
    set (MINGW_PREFIX ${MINGW_PREFIX} CACHE STRING "Prefix path to MinGW cross-compiler tools (MinGW cross-compiling build only)")
    if (NOT EXISTS ${MINGW_PREFIX}-gcc)
        message (FATAL_ERROR "Could not find MinGW cross compilation tool. "
            "Use MINGW_PREFIX environment variable or build option to specify the location of the toolchain.")
    endif ()
endif ()
if (NOT MINGW_COMPILER_PREFIX)
    set (MINGW_COMPILER_PREFIX ${MINGW_PREFIX})
    if ("$ENV{USE_CCACHE}")
        get_filename_component (PATH ${MINGW_PREFIX} PATH)
        get_filename_component (NAME ${MINGW_PREFIX} NAME)
        execute_process (COMMAND whereis -b ccache COMMAND grep -o \\S*lib\\S* OUTPUT_VARIABLE CCACHE_SYMLINK ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
        if (CCACHE_SYMLINK AND EXISTS ${CCACHE_SYMLINK}/${NAME}-gcc AND EXISTS ${CCACHE_SYMLINK}/${NAME}-g++)
            set (MINGW_COMPILER_PREFIX ${CCACHE_SYMLINK}/${NAME})
        else ()
            # Fallback to create the ccache symlink in the build tree itself
            execute_process (COMMAND which ccache RESULT_VARIABLE EXIT_CODE OUTPUT_VARIABLE CCACHE ERROR_QUIET OUTPUT_STRIP_TRAILING_WHITESPACE)
            if (EXIT_CODE EQUAL 0 AND CCACHE)
                foreach (TOOL gcc g++)
                    execute_process (COMMAND ${CMAKE_COMMAND} -E create_symlink ${CCACHE} ${CMAKE_BINARY_DIR}/${NAME}-${TOOL})
                endforeach ()
                set (MINGW_COMPILER_PREFIX ${CMAKE_BINARY_DIR}/${NAME})
            else ()
                message (WARNING "ccache may not have been installed on this host system. "
                    "This is required to enable ccache support for MinGW compiler toolchain. "
                    "CMake has been configured to use the actual compiler toolchain instead of ccache. "
                    "In order to rectify this, the build tree must be regenerated after installing ccache.")
            endif ()
        endif ()
        if (NOT MINGW_COMPILER_PREFIX STREQUAL MINGW_PREFIX AND NOT $ENV{PATH} MATCHES ${PATH})
            message (FATAL_ERROR "The bin directory containing the compiler toolchain (${PATH}) has not been added in the PATH environment variable. "
                "This is required to enable ccache support for MinGW compiler toolchain.")
        endif ()
    endif ()
    set (MINGW_COMPILER_PREFIX ${MINGW_COMPILER_PREFIX} CACHE INTERNAL "Path to C/C++ compiler tool symlinks or to the actual tools if not using ccache")
endif ()
set (CMAKE_C_COMPILER   ${MINGW_COMPILER_PREFIX}-gcc CACHE PATH "C compiler")
set (CMAKE_CXX_COMPILER ${MINGW_COMPILER_PREFIX}-g++ CACHE PATH "C++ compiler")
set (CMAKE_STRIP        ${MINGW_PREFIX}-strip        CACHE PATH "strip")
set (CMAKE_AR           ${MINGW_PREFIX}-ar           CACHE PATH "archive")
set (CMAKE_LINKER       ${MINGW_PREFIX}-ld           CACHE PATH "linker")
set (CMAKE_NM           ${MINGW_PREFIX}-nm           CACHE PATH "nm")
set (CMAKE_OBJCOPY      ${MINGW_PREFIX}-objcopy      CACHE PATH "objcopy")
set (CMAKE_OBJDUMP      ${MINGW_PREFIX}-objdump      CACHE PATH "objdump")
set (CMAKE_RANLIB       ${MINGW_PREFIX}-ranlib       CACHE PATH "ranlib")
set (CMAKE_RC_COMPILER  ${MINGW_PREFIX}-windres      CACHE PATH "RC compiler")

# System root
if (NOT IN_TRY_COMPILE AND NOT SAVED_MINGW_SYSROOT)
    if (NOT MINGW_SYSROOT)
        if (DEFINED ENV{MINGW_SYSROOT})
            file (TO_CMAKE_PATH $ENV{MINGW_SYSROOT} MINGW_SYSROOT)
        else ()
            execute_process (COMMAND ${CMAKE_COMMAND} -E echo "#include <_mingw.h>" COMMAND ${CMAKE_C_COMPILER} -E -M - OUTPUT_FILE ${CMAKE_BINARY_DIR}/find_mingw_sysroot_output ERROR_QUIET)
            file (STRINGS ${CMAKE_BINARY_DIR}/find_mingw_sysroot_output MINGW_SYSROOT REGEX _mingw\\.h)
            string (REGEX REPLACE "^[^ ]* *(.*)/include.*$" \\1 MINGW_SYSROOT "${MINGW_SYSROOT}")  # Stringify for string replacement
            string (REPLACE "\\ " " " MINGW_SYSROOT "${MINGW_SYSROOT}")
            execute_process (COMMAND ${CMAKE_COMMAND} -E remove find_mingw_sysroot_output)
        endif ()
    endif ()
    set (MINGW_SYSROOT ${MINGW_SYSROOT} CACHE PATH "Path to MinGW system root (MinGW only); should only be used when the system root could not be auto-detected")
    if (NOT EXISTS ${MINGW_SYSROOT})
        message (FATAL_ERROR "Could not find MinGW system root. "
            "Use MINGW_SYSROOT environment variable or build option to specify the location of system root.")
    endif ()
endif ()
set (CMAKE_FIND_ROOT_PATH ${MINGW_SYSROOT})     # Intentionally do not use CMAKE_SYSROOT because it does not work for MinGW compiler toolchain
# Only search libraries and headers in sysroot
set (CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set (CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set (CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

# Workaround try_compile() limitation where it cannot yet see cache variables during initial configuration
if (NOT IN_TRY_COMPILE)
    get_cmake_property (CACHE_VARIABLES CACHE_VARIABLES)
    foreach (VAR ${CACHE_VARIABLES})
        if (VAR MATCHES ^MINGW_|CMAKE_CX*_COMPILER)
            set (ENV{${VAR}} ${${VAR}})
            list (APPEND VARS ${VAR})
        endif ()
    endforeach ()
    set (ENV{VARS} "${VARS}")   # Stringify to keep the list together
endif ()