# Prepends flags to CMAKE_C_FLAGS if supported by the C compiler. Almost all
# flags should be prepended to allow the user to override them.
macro(WEBKIT_PREPEND_GLOBAL_C_FLAGS)
    foreach (_flag ${ARGN})
        check_c_compiler_flag("${_flag}" C_COMPILER_SUPPORTS_${_flag})
        if (C_COMPILER_SUPPORTS_${_flag})
            set(CMAKE_C_FLAGS "${_flag} ${CMAKE_C_FLAGS}")
        endif ()
    endforeach ()
endmacro()

# Appends flags to CMAKE_C_FLAGS if supported by the C compiler. This macro
# should be used sparingly. Only append flags if the user must not be allowed to
# override them.
macro(WEBKIT_APPEND_GLOBAL_C_FLAGS)
    foreach (_flag ${ARGN})
        check_c_compiler_flag("${_flag}" C_COMPILER_SUPPORTS_${_flag})
        if (C_COMPILER_SUPPORTS_${_flag})
            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${_flag}")
        endif ()
    endforeach ()
endmacro()

# Prepends flags to CMAKE_CXX_FLAGS if supported by the C++ compiler. Almost all
# flags should be prepended to allow the user to override them.
macro(WEBKIT_PREPEND_GLOBAL_CXX_FLAGS)
    foreach (_flag ${ARGN})
        check_cxx_compiler_flag("${_flag}" CXX_COMPILER_SUPPORTS_${_flag})
        if (CXX_COMPILER_SUPPORTS_${_flag})
            set(CMAKE_CXX_FLAGS "${_flag} ${CMAKE_CXX_FLAGS}")
        endif ()
    endforeach ()
endmacro()

# Appends flags to CMAKE_CXX_FLAGS if supported by the C++ compiler. This macro
# should be used sparingly. Only append flags if the user must not be allowed to
# override them.
macro(WEBKIT_APPEND_GLOBAL_CXX_FLAGS)
    foreach (_flag ${ARGN})
        check_cxx_compiler_flag("${_flag}" CXX_COMPILER_SUPPORTS_${_flag})
        if (CXX_COMPILER_SUPPORTS_${_flag})
            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_flag}")
        endif ()
    endforeach ()
endmacro()

# Prepends flags to CMAKE_C_FLAGS and CMAKE_CXX_FLAGS if supported by the C
# or C++ compiler, respectively. Almost all flags should be prepended to allow
# the user to override them.
macro(WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS)
    WEBKIT_PREPEND_GLOBAL_C_FLAGS(${ARGN})
    WEBKIT_PREPEND_GLOBAL_CXX_FLAGS(${ARGN})
endmacro()

# Appends flags to CMAKE_C_FLAGS and CMAKE_CXX_FLAGS if supported by the C or
# C++ compiler, respectively. This macro should be used sparingly. Only append
# flags if the user must not be allowed to override them.
macro(WEBKIT_APPEND_GLOBAL_COMPILER_FLAGS)
    WEBKIT_APPEND_GLOBAL_C_FLAGS(${ARGN})
    WEBKIT_APPEND_GLOBAL_CXX_FLAGS(${ARGN})
endmacro()

# Appends flags to COMPILE_FLAGS of _target if supported by the C compiler.
# Note that it is simply not possible to pass different C and C++ flags, unless
# we drop support for the Visual Studio backend and use the COMPILE_LANGUAGE
# generator expression. This is a very serious limitation.
macro(WEBKIT_ADD_TARGET_C_FLAGS _target)
    foreach (_flag ${ARGN})
        check_c_compiler_flag("${_flag}" C_COMPILER_SUPPORTS_${_flag})
        if (C_COMPILER_SUPPORTS_${_flag})
            target_compile_options(${_target} PRIVATE ${_flag})
        endif ()
    endforeach ()
endmacro()

# Appends flags to COMPILE_FLAGS of _target if supported by the C++ compiler.
# Note that it is simply not possible to pass different C and C++ flags, unless
# we drop support for the Visual Studio backend and use the COMPILE_LANGUAGE
# generator expression. This is a very serious limitation.
macro(WEBKIT_ADD_TARGET_CXX_FLAGS _target)
    foreach (_flag ${ARGN})
        check_cxx_compiler_flag("${_flag}" CXX_COMPILER_SUPPORTS_${_flag})
        if (CXX_COMPILER_SUPPORTS_${_flag})
            target_compile_options(${_target} PRIVATE ${_flag})
        endif ()
    endforeach ()
endmacro()


if (COMPILER_IS_GCC_OR_CLANG)
    WEBKIT_APPEND_GLOBAL_COMPILER_FLAGS(-fno-strict-aliasing)

    # clang-cl.exe impersonates cl.exe so some clang arguments like -fno-rtti are
    # represented using cl.exe's options and should not be passed as flags, so
    # we do not add -fno-rtti or -fno-exceptions for clang-cl
    if (COMPILER_IS_CLANG_CL)
        # FIXME: These warnings should be addressed
        WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-Wno-undef
                                             -Wno-macro-redefined
                                             -Wno-unknown-pragmas
                                             -Wno-nonportable-include-path
                                             -Wno-unknown-argument)
    else ()
        WEBKIT_APPEND_GLOBAL_COMPILER_FLAGS(-fno-exceptions)
        WEBKIT_APPEND_GLOBAL_CXX_FLAGS(-std=c++14
                                       -fno-rtti)

        if (WIN32)
            WEBKIT_APPEND_GLOBAL_COMPILER_FLAGS(-mno-ms-bitfields)
            WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-Wno-unknown-pragmas)
            add_definitions(-D__USE_MINGW_ANSI_STDIO=1)
        endif ()
    endif ()

    # Warnings to be enabled
    WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-Wall
                                         -Wextra
                                         -Wcast-align
                                         -Wformat-security
                                         -Wmissing-format-attribute
                                         -Wpointer-arith
                                         -Wundef
                                         -Wwrite-strings)

    # Warnings to be disabled
    # FIXME: We should probably not be disabling -Wno-maybe-uninitialized?
    WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-Qunused-arguments
                                         -Wno-maybe-uninitialized
                                         -Wno-noexcept-type
                                         -Wno-parentheses-equality)

    # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80947
    if (${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS "8.0" AND NOT CMAKE_CXX_COMPILER_ID MATCHES "Clang")
        WEBKIT_PREPEND_GLOBAL_CXX_FLAGS(-Wno-attributes)
    endif ()
endif ()

# -Wexpansion-to-defined produces false positives with GCC but not Clang
# https://bugs.webkit.org/show_bug.cgi?id=167643#c13
if (CMAKE_COMPILER_IS_GNUCXX)
    WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-Wno-expansion-to-defined)
endif ()

# Ninja tricks compilers into turning off color support.
if (CMAKE_GENERATOR STREQUAL "Ninja")
    WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-fcolor-diagnostics
                                         -fdiagnostics-color=always)
endif ()


string(TOLOWER ${CMAKE_HOST_SYSTEM_PROCESSOR} LOWERCASE_CMAKE_HOST_SYSTEM_PROCESSOR)
if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" AND NOT "${LOWERCASE_CMAKE_HOST_SYSTEM_PROCESSOR}" MATCHES "x86_64")
    # To avoid out of memory when building with debug option in 32bit system.
    # See https://bugs.webkit.org/show_bug.cgi?id=77327
    set(CMAKE_SHARED_LINKER_FLAGS_DEBUG "-Wl,--no-keep-memory ${CMAKE_SHARED_LINKER_FLAGS_DEBUG}")
endif ()

if (COMPILER_IS_GCC_OR_CLANG)
    # Careful: this needs to be above where ENABLED_COMPILER_SANITIZERS is set.
    # Also, it's not possible to use the normal prepend/append macros for
    # -fsanitize=address, because check_cxx_compiler_flag will report it's
    # unsupported, because it causes the build to fail if not used when linking.
    option(ENABLE_ADDRESS_SANITIZER "Enable address sanitizer" OFF)
    if (ENABLE_ADDRESS_SANITIZER)
        WEBKIT_PREPEND_GLOBAL_COMPILER_FLAGS(-fno-omit-frame-pointer
                                             -fno-optimize-sibling-calls)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address")
        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")
        set(CMAKE_EXE_LINKER_FLAGS "-lpthread ${CMAKE_EXE_LINKER_FLAGS} -fsanitize=address")
        set(CMAKE_SHARED_LINKER_FLAGS "-lpthread ${CMAKE_SHARED_LINKER_FLAGS} -fsanitize=address")
    endif ()
endif ()

if (NOT MSVC)
    string(REGEX MATCHALL "-fsanitize=[^ ]*" ENABLED_COMPILER_SANITIZERS ${CMAKE_CXX_FLAGS})
endif ()

if (UNIX AND NOT APPLE AND NOT ENABLED_COMPILER_SANITIZERS)
    set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_SHARED_LINKER_FLAGS}")
endif ()


# CODE_GENERATOR_PREPROCESSOR_WITH_LINEMARKERS only matters with GCC >= 4.7.0.  Since this
# version, -P does not output empty lines, which currently breaks make_names.pl in
# WebCore. Investigating whether make_names.pl should be changed instead is left as an exercise to
# the reader.
if (MSVC)
    set(CODE_GENERATOR_PREPROCESSOR_ARGUMENTS "/nologo /EP /TP")
    set(CODE_GENERATOR_PREPROCESSOR_WITH_LINEMARKERS_ARGUMENTS ${CODE_GENERATOR_PREPROCESSOR_ARGUMENTS})
else ()
    set(CODE_GENERATOR_PREPROCESSOR_ARGUMENTS "-E -P -x c++")
    set(CODE_GENERATOR_PREPROCESSOR_WITH_LINEMARKERS_ARGUMENTS "-E -x c++")
endif ()

set(CODE_GENERATOR_PREPROCESSOR "\"${CMAKE_CXX_COMPILER}\" ${CODE_GENERATOR_PREPROCESSOR_ARGUMENTS}")
set(CODE_GENERATOR_PREPROCESSOR_WITH_LINEMARKERS "\"${CMAKE_CXX_COMPILER}\" ${CODE_GENERATOR_PREPROCESSOR_WITH_LINEMARKERS_ARGUMENTS}")


# Ensure that the default include system directories are added to the list of CMake implicit includes.
# This workarounds an issue that happens when using GCC 6 and using system includes (-isystem).
# For more details check: https://bugs.webkit.org/show_bug.cgi?id=161697
macro(DETERMINE_GCC_SYSTEM_INCLUDE_DIRS _lang _compiler _flags _result)
    file(WRITE "${CMAKE_BINARY_DIR}/CMakeFiles/dummy" "\n")
    separate_arguments(_buildFlags UNIX_COMMAND "${_flags}")
    execute_process(COMMAND ${_compiler} ${_buildFlags} -v -E -x ${_lang} -dD dummy
                    WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/CMakeFiles OUTPUT_QUIET
                    ERROR_VARIABLE _gccOutput)
    file(REMOVE "${CMAKE_BINARY_DIR}/CMakeFiles/dummy")
    if ("${_gccOutput}" MATCHES "> search starts here[^\n]+\n *(.+) *\n *End of (search) list")
        set(${_result} ${CMAKE_MATCH_1})
        string(REPLACE "\n" " " ${_result} "${${_result}}")
        separate_arguments(${_result})
    endif ()
endmacro()

if (COMPILER_IS_GCC_OR_CLANG)
   DETERMINE_GCC_SYSTEM_INCLUDE_DIRS("c" "${CMAKE_C_COMPILER}" "${CMAKE_C_FLAGS}" SYSTEM_INCLUDE_DIRS)
   set(CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES ${CMAKE_C_IMPLICIT_INCLUDE_DIRECTORIES} ${SYSTEM_INCLUDE_DIRS})
   DETERMINE_GCC_SYSTEM_INCLUDE_DIRS("c++" "${CMAKE_CXX_COMPILER}" "${CMAKE_CXX_FLAGS}" SYSTEM_INCLUDE_DIRS)
   set(CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES ${CMAKE_CXX_IMPLICIT_INCLUDE_DIRECTORIES} ${SYSTEM_INCLUDE_DIRS})
endif ()