build.rs is trying to searching for header files in /usr/include instead of /ncnn/src

[shisoft]

Hi, I tried to build with cargo run --example get_version, both from source and prebuilt ncnn. Both of them failed with

   Compiling ncnn-bind v0.1.2 (/home/shisoft/rust-ncnn/ncnn-bind)
error: failed to run custom build command for `ncnn-bind v0.1.2 (/home/shisoft/rust-ncnn/ncnn-bind)`

Caused by:
  process didn't exit successfully: `/home/shisoft/rust-ncnn/target/debug/build/ncnn-bind-2a6ffcd248250f4e/build-script-build` (exit status: 101)
  --- stdout
  cargo:rerun-if-env-changed=NCNN_DIR
  cargo:rerun-if-env-changed=NCNN_TAG
  cargo:rustc-link-search=native=/home/shisoft/rust-ncnn/target/debug/build/ncnn-bind-97e51e1966ab29d8/out/lib
  cargo:rustc-link-search=native=/home/shisoft/rust-ncnn/target/debug/build/ncnn-bind-97e51e1966ab29d8/out/lib64
  cargo:rustc-link-lib=dylib=ncnn
  cargo:rustc-link-lib=dylib=pthread

  --- stderr
  error: header '/usr/include/c_api.h' does not exist.
  thread 'main' panicked at ncnn-bind/build.rs:305:10:
  Unable to generate bindings: ()
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

It seems like the build system is searching for headers at the wrong place. Is there anyway to fix it？

Thanks

[tpoisonooo]

roger that, fix it later.

I am working about many other things..

[matthewlyon23]

I had the same error and discovered it was because I was setting the NCNN_DIR variable incorrectly. Should point to the top level NCNN build folder, rather than the include folder like in some implementations. You can see this because the build.rs file appends include to the search path. Hope this helps.