Cross compile defaults to an incorrect toolchain

[NathanJSnyder]

F´ Version	v3.4.3
Affected Component	n/a

---

Problem Description

F' is failing to find the cross compile toolchain and defaults to /usr/bin/cc. This should show an error.

Context / Environment

Executed fprime-util version-check

Operating System: Linux
CPU Architecture: x86_64
Platform: Linux-5.4.0-172-generic-x86_64-with-glibc2.29
Python version: 3.8.10
CMake version: 3.16.3
Pip version: 24.0
Pip packages:
    fprime-tools==3.4.4
    fprime-gds==3.4.3
    fprime-fpp-*==2.1.0a3

Executed fprime-util generate aarch64-linux -DCMAKE_DEBUG_OUTPUT=ON

-- [arm-linux] Assembler:    CMAKE_ASM_COMPILER-NOTFOUND
-- [arm-linux] C   Compiler: CMAKE_C_COMPILER-NOTFOUND
-- [arm-linux] CXX Compiler: CMAKE_CXX_COMPILER-NOTFOUND
-- [arm-linux] Assembler:    CMAKE_ASM_COMPILER-NOTFOUND
-- [arm-linux] C   Compiler: CMAKE_C_COMPILER-NOTFOUND
-- [arm-linux] CXX Compiler: CMAKE_CXX_COMPILER-NOTFOUND
-- The C compiler identification is GNU 9.4.0
-- The CXX compiler identification is GNU 9.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done

How to Reproduce

1. Attempt to cross compile a project on this platform. (led-blinker was used in this case)

[roemvaar]

Is this a problem that needs to be fixed and what would be the "definition of done"? Just failing the compilation and displaying that no cross compiler was found?

If that's the case, I can tackle it

[NathanJSnyder]

It does need to be fixed and that is the expected solution. Thank you for looking into it!

[roemvaar]

The build is unsuccessful using a newer version of CMake. F' version is the same as the problem report.

Executed fprime-util version-check

Operating System: Linux
CPU Architecture: x86_64
Platform: Linux-6.5.0-25-generic-x86_64-with-glibc2.35
Python version: 3.10.12
CMake version: 3.22.1
Pip version: 24.0
Pip packages:
    fprime-tools==3.4.4
    fprime-gds==3.4.3
    fprime-fpp-*==2.1.0a3

Executed fprime-util generate aarch64-linux -DCMAKE_DEBUG_OUTPUT=ON

[INFO] Generating build directory at: /local/directory/led-blinker/build-fprime-automatic-aarch64-linux
[INFO] Using toolchain file /local/directory/led-blinker/fprime/cmake/toolchain/aarch64-linux.cmake for platform aarch64-linux
CMake Error at fprime/cmake/toolchain/helpers/arm-linux-base.cmake:20 (find_program):
-- Configuring incomplete, errors occurred!
  Could not find CMAKE_CXX_COMPILER using the following names:
  aarch64-linux-gnu-g++, aarch64-none-linux-gnu-g++
Call Stack (most recent call first):
  fprime/cmake/toolchain/aarch64-linux.cmake:18 (include)
  /usr/share/cmake-3.22/Modules/CMakeDetermineSystem.cmake:124 (include)
  CMakeLists.txt:7 (project)

CMake Error: CMake was unable to find a build program corresponding to "Unix Makefiles".  CMAKE_MAKE_PROGRAM is not set.  You probably need to select a different build tool.
[ERROR] CMake erred with return code 1. Partial build cache remains. Run purge to clean-up.

I'll try to use the same CMake version as the original bug report and see if I can reproduce the bug. Let me know if you have any thoughts.

[thomas-bc]

CMake was unable to find a build program corresponding to "Unix Makefiles". CMAKE_MAKE_PROGRAM is not set.

That's a really odd error that I've never seen before, does make --version work? What about fprime-util generate without the platform?

It may be weird artifacts of the earlier

  Could not find CMAKE_CXX_COMPILER using the following names:
  aarch64-linux-gnu-g++, aarch64-none-linux-gnu-g++

This seems to indicate your cross compilers are not installed properly. Which also seems to be why the issue appeared for OP (see -- [arm-linux] CXX Compiler: CMAKE_CXX_COMPILER-NOTFOUND in the original bug report)

@roemvaar @NathanJSnyder Were you both able to follow these cross-compilation setup steps?

[LeStarch]

Also, has make been installed on your linux system? You will need to install the cross-compilers too.

[roemvaar]

@thomas-bc I specifically didn't follow the "cross-compilation setup steps" to try and replicate the bug mentioned on the original post.

That's a really odd error that I've never seen before, does make --version work?

GNU Make 4.3
Built for x86_64-pc-linux-gnu

What about fprime-util generate without the platform?

This worked just fine.

@LeStarch make and all build tools, except for the cross-compiler, are installed on my setup.

I know my setup is working correctly because I was able to complete the HelloWorld tutorial. Now, I'm following the LedBlinker tutorial to turn on a LED on a BeagleBoneBlack. I know that if I install the xcompile tools and pass them as arguments to make the code will compile just fine, but I wanted to check what happened if I don't specify the directory of the aarch64 xcompiler. I was wondering if it would default to the native compiler for x86 (as mentioned on the bug report).

Any thoughts on what to do next to complete this task?

[thomas-bc]

Ohhh ok I understand. Then yes in my opinion it would make sense to error out in the generate step if xcompilers are not found, instead of defaulting back to the host's compilers. @LeStarch thoughts?

[LeStarch]

You need to set the path to the cross-compiler tools. Otherwise this setup won't work. To run the native (x86_64) compiler you may use:

fprime-util generate native
fprime-util build native

[LeStarch]

Ohhhhhh.....I lost track. This issue is in the original build, the CC compiler was used despite failing to find the ARM compiler. We need to error out.

[thomas-bc]

@roemvaar if you would like to tackle this, it would be a really good first issue to get familiar with our CMake system. Let us know!

[roemvaar]

Absolutely, I want to tackle this :)