Support for Minimal OpenCV Builds (e.g., opencv-mobile) with Selective Module Binding

[topcoco]

I'm using a minimal build of OpenCV (opencv-mobile : https://github.com/nihui/opencv-mobile ) which intentionally excludes certain modules (like CUDA) to reduce binary size. However, when using rust-opencv, the build system attempts to generate bindings for all OpenCV modules, even when the corresponding headers/files are missing from my installation.

​​Problem Example:​​
My opencv-mobile build deliberately removes opencv2/core/cuda.hpp since I don't need CUDA functionality. Despite specifying only the modules I need in Cargo.toml:

opencv = { version = "0.94.4", features = ["imgproc"], default-features = false }

The binding generator still tries to parse CUDA headers and fails with:

fatal error: 'opencv2/core/cuda.hpp' file not found

​​Request:​​
Could rust-opencv be modified to:

Respect missing headers in minimal OpenCV builds without failing?
Allow truly selective module binding generation?
Skip dependencies on optional components (like CUDA) when they're unavailable?

This would better support minimal OpenCV distributions where users explicitly want to exclude certain components.

​​Build Log Excerpt:​​

error: failed to run custom build command for opencv v0.94.4

Caused by:
process didn't exit successfully: /home/coco/RustroverProjects/untitled5/target/debug/build/opencv-e33045fc197b86be/build-script-build (exit status: 101)
--- stdout
cargo::rustc-check-cfg=cfg(ocvrs_opencv_branch_34)
cargo::rustc-check-cfg=cfg(ocvrs_opencv_branch_4)
cargo::rustc-check-cfg=cfg(ocvrs_opencv_branch_5)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_3d)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_alphamat)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_aruco)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_aruco_detector)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_barcode)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_bgsegm)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_bioinspired)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_calib)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_calib3d)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_ccalib)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_core)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudaarithm)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudabgsegm)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudacodec)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudafeatures2d)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudafilters)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudaimgproc)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudalegacy)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudaobjdetect)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudaoptflow)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudastereo)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cudawarping)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_cvv)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_dnn)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_dnn_superres)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_dpm)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_face)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_features)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_features2d)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_flann)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_freetype)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_fuzzy)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_gapi)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_hdf)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_hfs)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_highgui)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_img_hash)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_imgcodecs)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_imgproc)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_intensity_transform)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_line_descriptor)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_mcc)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_ml)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_objdetect)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_optflow)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_ovis)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_phase_unwrapping)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_photo)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_plot)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_quality)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_rapid)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_rgbd)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_saliency)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_sfm)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_shape)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_signal)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_stereo)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_stitching)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_structured_light)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_superres)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_surface_matching)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_text)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_tracking)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_video)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_videoio)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_videostab)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_viz)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_wechat_qrcode)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_xfeatures2d)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_ximgproc)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_xobjdetect)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_xphoto)
cargo::rustc-check-cfg=cfg(ocvrs_has_module_xstereo)
cargo::rustc-check-cfg=cfg(ocvrs_has_inherent_feature_hfloat)
cargo::rustc-check-cfg=cfg(ocvrs_has_inherent_feature_opencl)
cargo::rustc-cfg=ocvrs_opencv_branch_4
cargo::rustc-cfg=ocvrs_has_module_core
cargo::rustc-cfg=ocvrs_has_module_imgproc
cargo::rustc-cfg=ocvrs_has_inherent_feature_hfloat
cargo::rerun-if-env-changed=OPENCV_PACKAGE_NAME
cargo::rerun-if-env-changed=OPENCV_PKGCONFIG_NAME
cargo::rerun-if-env-changed=OPENCV_CMAKE_NAME
cargo::rerun-if-env-changed=OPENCV_CMAKE_BIN
cargo::rerun-if-env-changed=OPENCV_VCPKG_NAME
cargo::rerun-if-env-changed=OPENCV_LINK_LIBS
cargo::rerun-if-env-changed=OPENCV_LINK_PATHS
cargo::rerun-if-env-changed=OPENCV_INCLUDE_PATHS
cargo::rerun-if-env-changed=OPENCV_DISABLE_PROBES
cargo::rerun-if-env-changed=OPENCV_MSVC_CRT
cargo::rerun-if-env-changed=CMAKE_PREFIX_PATH
cargo::rerun-if-env-changed=OpenCV_DIR
cargo::rerun-if-env-changed=PKG_CONFIG_PATH
cargo::rerun-if-env-changed=VCPKG_ROOT
cargo::rerun-if-env-changed=VCPKGRS_DYNAMIC
cargo::rerun-if-env-changed=VCPKGRS_TRIPLET
cargo::rerun-if-env-changed=OCVRS_DOCS_GENERATE_DIR
cargo::rerun-if-env-changed=DOCS_RS
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/xfeatures2d.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/ccalib.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/manual-core.cpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/face.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/aruco.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/videoio.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/sfm.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/core.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/ocvrs_common.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/hdf.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/gapi.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/dnn.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/bioinspired.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/alphamat.hpp
cargo::rerun-if-changed=/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/photo.hpp
cargo::rerun-if-changed=Cargo.toml

--- stderr
=== Crate version: 0.94.4
=== Environment configuration:
=== OPENCV_PACKAGE_NAME = None
=== OPENCV_PKGCONFIG_NAME = None
=== OPENCV_CMAKE_NAME = None
=== OPENCV_CMAKE_BIN = None
=== OPENCV_VCPKG_NAME = None
=== OPENCV_LINK_LIBS = Some("static=opencv_highgui,static=opencv_videoio,static=opencv_imgproc,static=opencv_core,z,jpeg,png,webp")
=== OPENCV_LINK_PATHS = Some("/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/lib")
=== OPENCV_INCLUDE_PATHS = Some("/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4")
=== OPENCV_DISABLE_PROBES = Some("pkg_config,cmake,vcpkg")
=== OPENCV_MSVC_CRT = None
=== CMAKE_PREFIX_PATH = None
=== OpenCV_DIR = None
=== PKG_CONFIG_PATH = None
=== VCPKG_ROOT = None
=== VCPKGRS_DYNAMIC = None
=== VCPKGRS_TRIPLET = None
=== OCVRS_DOCS_GENERATE_DIR = None
=== DOCS_RS = None
=== PATH = Some("/home/coco/.cargo/bin:/usr/bin:/usr/bin:/home/coco/anaconda3/bin:/home/coco/anaconda3/condabin:/home/coco/.cargo/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin")
=== Enabled features:
=== CLANG_RUNTIME
=== IMGPROC
=== Detected probe priority boost based on environment vars: pkg_config: false, cmake: false, vcpkg: false
=== Probing the OpenCV library in the following order: environment, pkg_config, cmake, vcpkg_cmake, vcpkg
=== Configuring OpenCV library from the environment:
=== include_paths: /home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4
=== link_paths: /home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/lib
=== link_libs: static=opencv_highgui,static=opencv_videoio,static=opencv_imgproc,static=opencv_core,z,jpeg,png,webp
=== Successfully probed using: environment
=== OpenCV library configuration: Library {
include_paths: [
"/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4",
],
version: Version {
major: 4,
minor: 11,
patch: 0,
},
enabled_features: [
"pthread",
],
cargo_metadata: [
"cargo::rustc-link-search=/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/lib",
"cargo::rustc-link-lib=opencv_highgui",
"cargo::rustc-link-lib=opencv_videoio",
"cargo::rustc-link-lib=opencv_imgproc",
"cargo::rustc-link-lib=opencv_core",
"cargo::rustc-link-lib=z",
"cargo::rustc-link-lib=jpeg",
"cargo::rustc-link-lib=png",
"cargo::rustc-link-lib=webp",
],
}
=== Found OpenCV version: 4.11.0 in headers located at: /home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4
=== Detected OpenCV module header dir at: /home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4/opencv2
=== Generating code in: /home/coco/RustroverProjects/untitled5/target/debug/build/opencv-7da52440a0b622ec/out
=== Placing generated bindings into: /home/coco/RustroverProjects/untitled5/target/debug/build/opencv-7da52440a0b622ec/out/opencv
=== Using OpenCV headers from: /home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4
=== Clang: Ubuntu clang version 16.0.6 (23ubuntu4)
=== Clang command line args: [
"-isystem/usr/lib/gcc/x86_64-linux-gnu/13/../../../../include/c++/13",
"-isystem/usr/lib/gcc/x86_64-linux-gnu/13/../../../../include/x86_64-linux-gnu/c++/13",
"-isystem/usr/lib/gcc/x86_64-linux-gnu/13/../../../../include/c++/13/backward",
"-isystem/usr/lib/llvm-16/lib/clang/16/include",
"-isystem/usr/local/include",
"-isystem/usr/include/x86_64-linux-gnu",
"-isystem/usr/include",
"-I/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4",
"-F/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4",
"-I/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp",
"-F/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp",
"-DOCVRS_PARSING_HEADERS",
"-includeocvrs_common.hpp",
"-std=c++17",
]
=== Using environment job server with the the amount of available jobs: 16
=== Generating 2 modules
=== Running: "/home/coco/RustroverProjects/untitled5/target/debug/build/opencv-e33045fc197b86be/build-script-build" "/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4" "/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp" "/home/coco/RustroverProjects/untitled5/target/debug/build/opencv-7da52440a0b622ec/out" "core" ""
=== Running: "/home/coco/RustroverProjects/untitled5/target/debug/build/opencv-e33045fc197b86be/build-script-build" "/home/coco/RustroverProjects/nnpp2/opencv-mobile-4.11.0-ubuntu-2404/include/opencv4" "/home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp" "/home/coco/RustroverProjects/untitled5/target/debug/build/opencv-7da52440a0b622ec/out" "imgproc" ""
=== WARNING: 1 diagnostic messages
=== /home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/src_cpp/core.hpp:12:10: fatal error: 'opencv2/core/cuda.hpp' file not found

thread 'main' panicked at /home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-binding-generator-0.96.1/src/generator.rs:424:17:
=== Errors during header parsing
note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

thread 'gen-core' panicked at /home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/build/generator.rs:127:37:
Failed to run the bindings generator for module: core
note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

thread 'main' panicked at /home/coco/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/opencv-0.94.4/build/generator.rs:137:36:
Generator process panicked: Any { .. }
=== Generated: imgproc in 1.410224813s

[twistedfall]

Hi, I was not aware of such OpenCV mod before, I'll take a look.

Respect missing headers in minimal OpenCV builds without failing?

Can you please check crate v0.95, the CUDA problem should be fixed in it.

Allow truly selective module binding generation?

In this case CUDA is not a separate module, but a extension to some of the modules. From version 0.95 it should now be easier to take that into account.

Skip dependencies on optional components (like CUDA) when they're unavailable?

It's not a dependency per se, but you can now use opencv_has_inherent_feature_cuda! macro to do conditional compilation based on whether CUDA is enabled in OpenCV.