nextcloud-desktop/cmake/Modules/DefineCompilerFlags.cmake

# define system dependent compiler flags

include(CheckCCompilerFlag)
include(MacroCheckCCompilerFlagSSP)

#
# Define GNUCC compiler flags
#
if (${CMAKE_C_COMPILER_ID} MATCHES "(GNU|Clang)")

    # add -Wconversion ?
    # cannot be pedantic with sqlite3 directly linked
    if (NOT CSYNC_STATIC_COMPILE_DIR)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99 -pedantic -pedantic-errors")
    endif()
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wshadow -Wmissing-prototypes -Wdeclaration-after-statement")
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wunused -Wfloat-equal -Wpointer-arith -Wwrite-strings -Wformat-security")
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-format-attribute")
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-format-attribute -D_GNU_SOURCE")

    set(CSYNC_STRICT ON CACHE BOOL "Strict error checking, enabled -Werror and friends")
    if (CSYNC_STRICT)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__STDC_FORMAT_MACROS=1")
    endif(CSYNC_STRICT)

    # with -fPIC
    check_c_compiler_flag("-fPIC" WITH_FPIC)
    if (WITH_FPIC AND NOT WIN32)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
    endif (WITH_FPIC AND NOT WIN32)

    check_c_compiler_flag_ssp("-fstack-protector" WITH_STACK_PROTECTOR)
    if (WITH_STACK_PROTECTOR AND NOT WIN32)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fstack-protector")
    endif (WITH_STACK_PROTECTOR AND NOT WIN32)

    if (WITH_OPTIMIZATION)
    check_c_compiler_flag("-D_FORTIFY_SOURCE=2" WITH_FORTIFY_SOURCE)
        if (WITH_FORTIFY_SOURCE)
            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O -D_FORTIFY_SOURCE=2")
        endif (WITH_FORTIFY_SOURCE)
    endif (WITH_OPTIMIZATION)
endif (${CMAKE_C_COMPILER_ID} MATCHES "(GNU|Clang)")

if (UNIX AND NOT WIN32)
    #
    # Check for large filesystem support
    #
    if (CMAKE_SIZEOF_VOID_P MATCHES "8")
        # with large file support
        execute_process(
            COMMAND
                getconf LFS64_CFLAGS
            OUTPUT_VARIABLE
                _lfs_CFLAGS
            ERROR_QUIET
            OUTPUT_STRIP_TRAILING_WHITESPACE
        )
    else (CMAKE_SIZEOF_VOID_P MATCHES "8")
        # with large file support
        execute_process(
            COMMAND
                getconf LFS_CFLAGS
            OUTPUT_VARIABLE
                _lfs_CFLAGS
            ERROR_QUIET
            OUTPUT_STRIP_TRAILING_WHITESPACE
        )
    endif (CMAKE_SIZEOF_VOID_P MATCHES "8")
    if (_lfs_CFLAGS)
        string(REGEX REPLACE "[\r\n]" " " "${_lfs_CFLAGS}" "${${_lfs_CFLAGS}}")
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${_lfs_CFLAGS}")
    endif (_lfs_CFLAGS)
else(UNIX AND NOT WIN32)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_FILE_OFFSET_BITS=64")
endif (UNIX AND NOT WIN32)