How to see full BPF build errors?

[akshatagarwl]

Currently if my BPF program is not valid and I try to build it I don't get the full errors. Just this:

error: failed to run custom build command for `project v0.1.0 (/home/akshat/wrkspc/project)`

Caused by:
  process didn't exit successfully: `/home/akshat/wrkspc/project/target/debug/build/project-f2b462afc857728b/build-script-build` (exit status: 101)
  --- stderr
  libbpf: failed to find BTF info for global/extern symbol 'get_details'
  thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Build("Failed to strip object file /tmp/nix-shell.ehZiWP/.tmpkJ2AEc/project.o")', build.rs:14:10
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

To see the full errors I can do a

clang -target bpf -D __TARGET_ARCH_x86 -I/home/akshat/wrkspc/project/target/debug/build/libbpf-sys-9d5531770fa8ac90/out/include/ -Wall -O2 -g -fno-stack-protector -o project.bpf.o -c project.bpf.c

But this adds an extra step during the development process which is not directly in line with the usual cargo build route

[danielocfb]

Please provide an example reproducing the problem.

[taikulawo]

on v0.21.1 it will print command line args when failed but it hidden by to_string
#513

[danielocfb]

#513 has been merged.

[akshat-aurva]

@danielocfb This still doesn't seem to work bases on the build.rs provided in the PR. Can you provide a minimal example where I can see this?

[danielocfb]

https://github.com/libbpf/libbpf-rs/blob/master/examples/capable/build.rs