# toolchain.cmake
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR x86_64)

# C 和 C++ 编译器
set(CMAKE_C_COMPILER gcc)
set(CMAKE_CXX_COMPILER g++)

# 查找路径
set(CMAKE_FIND_ROOT_PATH /usr/local)

# 查找策略
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake

# arm-linux-toolchain.cmake
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

# 交叉编译工具链前缀
set(CROSS_COMPILE arm-linux-gnueabihf-)

set(CMAKE_C_COMPILER ${CROSS_COMPILE}gcc)
set(CMAKE_CXX_COMPILER ${CROSS_COMPILE}g++)
set(CMAKE_AR ${CROSS_COMPILE}ar)
set(CMAKE_RANLIB ${CROSS_COMPILE}ranlib)
set(CMAKE_STRIP ${CROSS_COMPILE}strip)

# sysroot（目标系统的根文件系统）
set(CMAKE_SYSROOT /opt/arm-sysroot)
set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})

# 查找策略
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

# 安装交叉编译工具链
sudo apt install gcc-arm-linux-gnueabihf g++-arm-linux-gnueabihf

# 构建
cmake -S . -B build \
    -DCMAKE_TOOLCHAIN_FILE=arm-linux-toolchain.cmake \
    -DCMAKE_BUILD_TYPE=Release
cmake --build build

# aarch64-toolchain.cmake
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR aarch64)

set(CMAKE_C_COMPILER aarch64-linux-gnu-gcc)
set(CMAKE_CXX_COMPILER aarch64-linux-gnu-g++)

set(CMAKE_FIND_ROOT_PATH /usr/aarch64-linux-gnu)
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

# mingw-toolchain.cmake
set(CMAKE_SYSTEM_NAME Windows)
set(CMAKE_SYSTEM_PROCESSOR x86_64)

set(CMAKE_C_COMPILER x86_64-w64-mingw32-gcc)
set(CMAKE_CXX_COMPILER x86_64-w64-mingw32-g++)
set(CMAKE_RC_COMPILER x86_64-w64-mingw32-windres)

set(CMAKE_FIND_ROOT_PATH /usr/x86_64-w64-mingw32)
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

# ios-toolchain.cmake
set(CMAKE_SYSTEM_NAME iOS)
set(CMAKE_OSX_ARCHITECTURES arm64)
set(CMAKE_OSX_DEPLOYMENT_TARGET "14.0")

# SDK 路径
set(CMAKE_OSX_SYSROOT iphoneos)

# 禁用在目标上查找
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)

project(MyApp LANGUAGES CXX)

message("C++ 编译器: ${CMAKE_CXX_COMPILER}")
message("编译器 ID: ${CMAKE_CXX_COMPILER_ID}")
message("编译器版本: ${CMAKE_CXX_COMPILER_VERSION}")
message("编译器路径: ${CMAKE_CXX_COMPILER}")

# 方式一：使用 if 判断
if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    target_compile_options(myapp PRIVATE -Wall -Wextra -Wpedantic)
elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
    target_compile_options(myapp PRIVATE -Wall -Wextra -Wpedantic)
elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
    target_compile_options(myapp PRIVATE /W4 /WX)
endif()

# 方式二：使用生成器表达式（推荐）
target_compile_options(myapp PRIVATE
    $<$<CXX_COMPILER_ID:GNU,Clang>:-Wall -Wextra -Wpedantic>
    $<$<CXX_COMPILER_ID:MSVC>:/W4 /WX>
)

include(CheckCXXCompilerFlag)

# 检查编译器标志
check_cxx_compiler_flag("-fsanitize=address" HAS_ASAN)
check_cxx_compiler_flag("-march=native" HAS_MARCH_NATIVE)

if(HAS_ASAN AND ENABLE_SANITIZERS)
    add_compile_options(-fsanitize=address)
    add_link_options(-fsanitize=address)
endif()

# 方式一：使用 CMAKE 变量（旧风格）
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

# 方式二：使用 target_compile_features（推荐）
target_compile_features(mylib PUBLIC cxx_std_17)

add_library(mylib src/mylib.cpp)
set_target_properties(mylib PROPERTIES
    CXX_STANDARD 17
    CXX_STANDARD_REQUIRED ON
    CXX_EXTENSIONS OFF
)

set(CMAKE_C_STANDARD 11)
set(CMAKE_C_STANDARD_REQUIRED ON)
set(CMAKE_C_EXTENSIONS OFF)

# 或
target_compile_features(mylib PUBLIC c_std_11)

# 操作系统
message("系统名: ${CMAKE_SYSTEM_NAME}")      # Linux, Darwin, Windows
message("系统版本: ${CMAKE_SYSTEM_VERSION}")
message("处理器: ${CMAKE_SYSTEM_PROCESSOR}")  # x86_64, aarch64

# 平台判断
if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
    message("Linux 平台")
endif()
if(APPLE)
    message("macOS/iOS 平台")
endif()
if(WIN32)
    message("Windows 平台")
endif()
if(UNIX)
    message("Unix 平台（包括 macOS 和 Linux）")
endif()

# Android
if(CMAKE_SYSTEM_NAME STREQUAL "Android")
    message("Android: API level ${CMAKE_SYSTEM_VERSION}")
endif()

# 检测架构
if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64")
    message("x86_64 架构")
elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64|arm64")
    message("ARM64 架构")
elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm")
    message("ARM32 架构")
endif()

include(CheckTypeSize)
check_type_size("void*" SIZEOF_VOID_P)
message("指针大小: ${SIZEOF_VOID_P} 字节")

include(CheckIncludeFileCXX)
check_include_file_cxx("filesystem" HAS_FILESYSTEM)
check_include_file_cxx("optional" HAS_OPTIONAL)

include(CheckCXXSymbolExists)
check_cxx_symbol_exists(getentropy "unistd.h" HAS_GETENTROPY)

include(CheckLibraryExists)
check_library_exists(m sin "" HAS_LIBM)
if(HAS_LIBM)
    target_link_libraries(myapp PRIVATE m)
endif()

# 设置全局标志（所有目标）
add_compile_options(-Wall -Wextra)

# 按语言设置
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-std=c++17>)
add_compile_options($<$<COMPILE_LANGUAGE:C>:-std=c11>)

# 设置全局定义
add_definitions(-DDEBUG_MODE)
add_definitions(-DVERSION="1.0")

# 全局链接选项
add_link_options(-fsanitize=address)

# 目标级别
target_link_options(myapp PRIVATE
    $<$<CXX_COMPILER_ID:GNU>:-Wl,--as-needed>
)

# Debug 特有选项
set(CMAKE_CXX_FLAGS_DEBUG "-g -O0 -DDEBUG")

# Release 特有选项
set(CMAKE_CXX_FLAGS_RELEASE "-O3 -DNDEBUG")

# RelWithDebInfo
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g -DNDEBUG")

# 推荐方式：使用生成器表达式
target_compile_options(myapp PRIVATE
    $<$<CONFIG:Debug>:-g -O0>
    $<$<CONFIG:Release>:-O3 -DNDEBUG>
)

# CMake 3.16+ 支持预编译头
target_precompile_headers(mylib PRIVATE
    <vector>
    <string>
    <memory>
    <algorithm>
)

# 或使用自定义头文件
target_precompile_headers(mylib PRIVATE
    "src/pch.h"
)

{
    "version": 6,
    "configurePresets": [
        {
            "name": "arm-linux",
            "toolchainFile": "${sourceDir}/cmake/arm-linux-toolchain.cmake",
            "generator": "Ninja",
            "binaryDir": "${sourceDir}/build-arm"
        },
        {
            "name": "native-debug",
            "generator": "Ninja",
            "binaryDir": "${sourceDir}/build-debug",
            "cacheVariables": {
                "CMAKE_BUILD_TYPE": "Debug"
            }
        }
    ]
}

cmake --list-presets
cmake --preset arm-linux
cmake --build --preset arm-linux

# stm32-toolchain.cmake
set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_SYSTEM_PROCESSOR cortex-m4)

set(CMAKE_C_COMPILER arm-none-eabi-gcc)
set(CMAKE_CXX_COMPILER arm-none-eabi-g++)
set(CMAKE_ASM_COMPILER arm-none-eabi-gcc)
set(CMAKE_OBJCOPY arm-none-eabi-objcopy)
set(CMAKE_SIZE arm-none-eabi-size)

# 芯片特定标志
set(CPU_FLAGS "-mcpu=cortex-m4 -mthumb -mfloat-abi=hard -mfpu=fpv4-sp-d16")

set(CMAKE_C_FLAGS_INIT "${CPU_FLAGS} -fdata-sections -ffunction-sections")
set(CMAKE_CXX_FLAGS_INIT "${CPU_FLAGS} -fdata-sections -ffunction-sections -fno-rtti -fno-exceptions")
set(CMAKE_EXE_LINKER_FLAGS_INIT "${CPU_FLAGS} -Wl,--gc-sections -T${CMAKE_SOURCE_DIR}/linker.ld")

# 禁用编译器检查（交叉编译无法运行目标二进制）
set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)