我正在尝试在 windows 上使用 make 但它给出错误

Question

I´m trying to make this project https://github.com/Slamtec/rplidar_sdk . But when i run the make command i get the following error:

In file included from src/sl_lidar_driver.cpp:40:
src/hal/event.h: In member function 'long unsigned int rp::hal::Event::wait(long unsigned int)':
src/hal/event.h:108:20: warning: conversion from 'rp::hal::Event::<unnamed enum>' to 'long unsigned int' changes value from 'rp::hal::Event::EVENT_TIMEOUT' to '4294967295' [-Woverflow]
  108 |             return EVENT_TIMEOUT;
      |                    ^~~~~~~~~~~~~
src/sl_lidar_driver.cpp: In member function 'virtual sl_result sl::SlamtecLidarDriver::grabScanDataHq(sl_lidar_response_measurement_node_hq_t*, size_t&, sl_u32)':
src/sl_lidar_driver.cpp:556:34: error: narrowing conversion of 'rp::hal::Event::EVENT_TIMEOUT' from 'long long unsigned int' to 'long unsigned int' [-Wnarrowing]
  556 |             case rp::hal::Event::EVENT_TIMEOUT:
      |                                  ^~~~~~~~~~~~~
src/sl_lidar_driver.cpp:556:13: warning: conversion from 'long long unsigned int' to 'long unsigned int' changes value from '18446744073709551615' to '4294967295' [-Woverflow]
  556 |             case rp::hal::Event::EVENT_TIMEOUT:
      |             ^~~~
src/sl_lidar_driver.cpp: In member function 'sl_result sl::SlamtecLidarDriver::_sendCommand(sl_u16, const void*, size_t)':
src/sl_lidar_driver.cpp:1089:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<unsigned char>::size_type' {aka 'long long unsigned int'} [-Wsign-compare]
 1089 |             for (int pos = 0; pos < cmd_packet.size(); pos++) {
      |                               ~~~~^~~~~~~~~~~~~~~~~~~
src/sl_lidar_driver.cpp:1058:19: warning: unused variable 'pkt_header' [-Wunused-variable]
 1058 |             sl_u8 pkt_header[10];
      |                   ^~~~~~~~~~
src/sl_lidar_driver.cpp: In member function 'void sl::SlamtecLidarDriver::_ultraCapsuleToNormal(const sl_lidar_response_ultra_capsule_measurement_nodes_t&, sl_lidar_response_measurement_node_hq_t*, size_t&)':
src/sl_lidar_driver.cpp:1370:40: warning: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Wsign-compare]
 1370 |                     if ((dist_predict1 == 0xFFFFFE00) || (dist_predict1 == 0x1FF)) {
      |                          ~~~~~~~~~~~~~~^~~~~~~~~~~~~
src/sl_lidar_driver.cpp:1379:40: warning: comparison of integer expressions of different signedness: 'int' and 'unsigned int' [-Wsign-compare]
 1379 |                     if ((dist_predict2 == 0xFFFFFE00) || (dist_predict2 == 0x1FF)) {
      |                          ~~~~~~~~~~~~~~^~~~~~~~~~~~~
src/sl_lidar_driver.cpp: At global scope:
src/sl_lidar_driver.cpp:72:17: warning: 'void sl::convert(const sl_lidar_response_measurement_node_hq_t&, sl_lidar_response_measurement_node_t&)' defined but not used [-Wunused-function]
   72 |     static void convert(const sl_lidar_response_measurement_node_hq_t& from, sl_lidar_response_measurement_node_t& to)
      |                 ^~~~~~~
src/sl_lidar_driver.cpp:59:17: warning: 'void sl::printDeprecationWarn(const char*, const char*)' defined but not used [-Wunused-function]
   59 |     static void printDeprecationWarn(const char* fn, const char* replacement)
    make[1]: *** [/c/rplidar_sdk/mak_common.inc:82: /c/rplidar_sdk/obj/MSYS_NT-10.0-19044/Release/sdk/src/sl_lidar_driver.o] Error 1
    make[1]: Leaving directory '/c/rplidar_sdk/sdk'
    make: *** [/c/rplidar_sdk/mak_common.inc:43: make_subs] Error 1

someone could tell me why i getting this error and how to solved it?

Answer 1

Apparently this code is not portable.

It appears to assume that a long int is 64bits (8 bytes) long, which is true on Linux and MacOS. But on Windows, a long int is only 32bits (4 bytes) long.

C and C++ have 5 integral types (ignoring the unsigned versions): char , short , int , long , long long . The C standard gives a minimum range of integers that must fit into these types, but it doesn't give a maximum . It's up to the implementation. See https://en.wikipedia.org/wiki/C_data_types#Main_types

A modern system has native support for 4 sizes of integer: 1 byte, 2 bytes, 4 bytes, 8 bytes.

So you can see that in order to map 5 types onto 4 sizes, two of the types must map to the same size.

Linux and MacOS choose to have int be 4 bytes and long and long long both be 8 bytes. Windows chooses to have int and long both be 4 bytes, and long long be 8 bytes. See https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models

If the code is written to assume that long and long long are the same size and can be used interchangeably, then you'll get errors like the ones you're seeing when you try to compile it on Windows.