A compile error about sitl

ArduCopter
1

I setup the ardupilot SITL following this tutorial(https://ardupilot.org/dev/docs/setting-up-sitl-on-linux.html).
When I run the command ‘sim_vehicle.py -w’, a compile error occured like below:

 ......
[616/697] Compiling libraries/AC_Avoidance/AP_OAPathPlanner.cpp
[617/697] Compiling libraries/AP_ADSB/AP_ADSB.cpp
[618/697] Compiling libraries/AP_GyroFFT/AP_GyroFFT.cpp
[619/697] Compiling libraries/AP_RCTelemetry/AP_RCTelemetry.cpp
../../libraries/AP_GyroFFT/AP_GyroFFT.cpp: In member function ‘uint16_t AP_GyroFFT::run_cycle()’:
../../libraries/AP_GyroFFT/AP_GyroFFT.cpp:387:33: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
     if (gyro_buffer.available() > _state->_window_size + uint16_t(_samples_per_frame >> 1)) { // half the frame size is a heuristic
                                 ^
compilation terminated due to -Wfatal-errors.
cc1plus: some warnings being treated as errors

Waf: Leaving directory `/home/ubuntu-li/ardupilot/build/sitl'
Build failed
 -> task in 'objs/AP_GyroFFT/ArduCopter' failed (exit status 1): 
	{task 139976827606392: cxx AP_GyroFFT.cpp -> AP_GyroFFT.cpp.3.o}
 (run with -v to display more information)
SIM_VEHICLE: Build failed
SIM_VEHICLE: Killing tasks
SIM_VEHICLE: kill_tasks failed: 'Process' object has no attribute 'environ'

What can I do for this error, anyone can help me?

2

You’re not doing anything wrong.

That’s a bug in the code.

@andyp1per

A patch like this might get you going:

diff --git a/libraries/AP_GyroFFT/AP_GyroFFT.cpp b/libraries/AP_GyroFFT/AP_GyroFFT.cpp
index 849be3ebe6..ebf9277f0a 100644
--- a/libraries/AP_GyroFFT/AP_GyroFFT.cpp
+++ b/libraries/AP_GyroFFT/AP_GyroFFT.cpp
@@ -384,7 +384,7 @@ uint16_t AP_GyroFFT::run_cycle()
     FloatBuffer& gyro_buffer = (_sample_mode == 0 ?_ins->get_raw_gyro_window(_update_axis) : _downsampled_gyro_data[_update_axis]);
     // if we have many more samples than the window size then we are struggling to 
     // stay ahead of the gyro loop so drop samples so that this cycle will use all available samples
-    if (gyro_buffer.available() > _state->_window_size + uint16_t(_samples_per_frame >> 1)) { // half the frame size is a heuristic
+    if (gyro_buffer.available() > unsigned(_state->_window_size + uint16_t(_samples_per_frame >> 1))) { // half the frame size is a heuristic
         gyro_buffer.advance(gyro_buffer.available() - _state->_window_size);
     }
     // let's go!

(that’s probably not the correct fix, but you probably don’t care about that!)

3

Maybe you should change the uint16_t to int

4

@githublearner-li - what compiler and version are you using?

5

This code compiles in CI and is technically correct, there is something more weird going on here.
My compiler version (which it compiles fine with) is:

andy@Eagle:~/github/ardupilot-dev$ g++ --version
g++ (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
Copyright © 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

6

Thank you! I will try it:)

7

My compiler and version is shown below:

g++ (Ubuntu 5.4.0-6ubuntu1~16.04.12) 5.4.0 20160609
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

is it outdated or do I need to update it to the newest version?

8

It works! Thank you so much !

9

OK, I think this problem has been solved with you guys’ help :smiley: Thanks for your help!

10

@githublearner-li how did you solve this problem??

11

Hi,

running into the same issue, how did you fix it?

12

Use gcc 6 or later

More words

13

awesome thanks for that.

Fixed it by updating my gcc version, instructions here: https://gist.github.com/zuyu/7d5682a5c75282c596449758d21db5ed

14

I’m so sorry to answer you so late and congratulations on solving this problem. I solved this error by @peterbarker 's patch as written above(A compile error about sitl - #2 by peterbarker).

The whole process is:

  1. open the ardupilot folder in your machine, find the ../libraries/AP_GyroFFT/AP_GyroFFT.cpp and open it.
  2. find this the line 387: if (gyro_buffer.available() > _state->_window_size + uint16_t(_samples_per_frame >> 1)) { // half the frame size is a heuristic
  3. change it to if (gyro_buffer.available() > unsigned(_state->_window_size + uint16_t(_samples_per_frame >> 1))) { // half the frame size is a heuristic
  4. compile it again and you will find it works.
15

Updating GCC works like a charm thank you.