opencv-rust breaks profiling scenarios

[montekki]

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1. Operating system: ubuntu 21.10
2. The way you installed OpenCV: manual compilation
3. OpenCV version: from ubuntu packages:
   Package: libopencv-core4.5
   Version: 4.5.3+dfsg-1ubuntu1
   New: yes
4. rustc version (rustc --version): rustc 1.64.0-nightly (2f3ddd9f5 2022-06-27)

Trying to run the standard grcov workflow seems broken due to some dead code not being eliminated:

env CARGO_INCREMENTAL=0 RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort"  RUSTDOCFLAGS="-Cpanic=abort" cargo test --all-features --no-fail-fast

 = note: /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.11xbdp47wnty2i45.rcgu.o: in function `opencv::opencv::hub::imgproc::bounding_rect':
          /tmp/opencv-rust/src/opencv/hub/imgproc.rs:2746: undefined reference to `cv_boundingRect_const__InputArrayR'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.11xbdp47wnty2i45.rcgu.o: in function `opencv::opencv::hub::imgproc::min_area_rect':
          /tmp/opencv-rust/src/opencv/hub/imgproc.rs:5790: undefined reference to `cv_minAreaRect_const__InputArrayR'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.11xbdp47wnty2i45.rcgu.o: in function `opencv::opencv::hub::imgproc::get_structuring_element':
          /tmp/opencv-rust/src/opencv/hub/imgproc.rs:5132: undefined reference to `cv_getStructuringElement_int_Size_Point'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.1wqrjlo7a4mr3vpi.rcgu.o: in function `opencv::opencv::hub::highgui::named_window':
          /tmp/opencv-rust/src/opencv/hub/highgui.rs:853: undefined reference to `cv_namedWindow_const_StringR_int'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.1wqrjlo7a4mr3vpi.rcgu.o: in function `opencv::opencv::hub::highgui::create_trackbar':
          /tmp/opencv-rust/src/opencv/hub/highgui.rs:524: undefined reference to `cv_createTrackbar_const_StringR_const_StringR_intX_int_TrackbarCallback_voidX'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.1wqrjlo7a4mr3vpi.rcgu.o: in function `opencv::opencv::hub::highgui::set_trackbar_pos':
          /tmp/opencv-rust/src/opencv/hub/highgui.rs:1207: undefined reference to `cv_setTrackbarPos_const_StringR_const_StringR_int'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.1wtqmdt5zd0woqn6.rcgu.o: in function `opencv::opencv::hub::aruco::DetectorParameters::create':
          /tmp/opencv-rust/src/opencv/hub/aruco.rs:1710: undefined reference to `cv_aruco_DetectorParameters_create'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.1wtqmdt5zd0woqn6.rcgu.o: in function `opencv::opencv::hub::aruco::DetectorParameters::default':
          /tmp/opencv-rust/src/opencv/hub/aruco.rs:1700: undefined reference to `cv_aruco_DetectorParameters_DetectorParameters'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::FileStorage::new':
          /tmp/opencv-rust/src/opencv/hub/core.rs:10285: undefined reference to `cv_FileStorage_FileStorage_const_StringR_int_const_StringR'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::_InputArray::from_mat':
          /tmp/opencv-rust/src/opencv/hub/core.rs:20484: undefined reference to `cv__InputArray__InputArray_const_MatR'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::use_optimized':
          /tmp/opencv-rust/src/opencv/hub/core.rs:7442: undefined reference to `cv_useOptimized'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::get_tick_count':
          /tmp/opencv-rust/src/opencv/hub/core.rs:3893: undefined reference to `cv_getTickCount'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::type_to_string':
          /tmp/opencv-rust/src/opencv/hub/core.rs:7419: undefined reference to `cv_typeToString_int'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::set_use_optimized':
          /tmp/opencv-rust/src/opencv/hub/core.rs:6945: undefined reference to `cv_setUseOptimized_bool'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::get_cpu_tick_count':
          /tmp/opencv-rust/src/opencv/hub/core.rs:3755: undefined reference to `cv_getCPUTickCount'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::get_number_of_cpus':
          /tmp/opencv-rust/src/opencv/hub/core.rs:3821: undefined reference to `cv_getNumberOfCPUs'
          /usr/bin/ld: /tmp/opencv-rust/target/debug/deps/marshalling-616d85a659d99857.3nkvkx3dpia7qndu.rcgu.o: in function `opencv::opencv::hub::core::get_tick_frequency':
          /tmp/opencv-rust/src/opencv/hub/core.rs:3913: undefined reference to `cv_getTickFrequency'

So in case the crate has opencv-rust as a dependency it cannot be profiled atm

[twistedfall]

That's a lot of undefined references even to the basic things, are the opencv so's getting linked at all? I'm not really familiar with this profiling workflow, can you please provide the instructions to reproduce the issue?

[montekki]

I just run this in the repo (has to be nightly rustc):

CARGO_INCREMENTAL=0 RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort"  RUSTDOCFLAGS="-Cpanic=abort" cargo test --all-features --no-fail-fast

[twistedfall]

From my testing it looks like the particular culprit is -Clink-dead-code, not the -Zprofile by itself and there is an open bugreport regarding very similar issue: rust-lang/rust#64685 Looks like you would need to wait until this is fixed or adjust the pipeline to not include the -Clink-dead-code.