Cargo adding -L '' to rustc command causing failing build (Windows cross-compile)

I have a project using qmetaobject-rs and rust-ac-ffmpeg, both of which use C++ and C libraries respectively. I'm cross-compiling for windows in a Ubuntu container and linking against the correct DLL's as far as I can tell.

This is the Dockerfile used for the build: WindowsCrosscompile.Dockerfile · windows-cxc · Cryptocam / cryptocam-companion · GitLab

The interesting build command:

CFLAGS="-static-libgcc -Wl,-Bstatic,-lpthread,-Wl,-Bdynamic" CXXFLAGS="-static-libgcc -static-libstdc++ -Wl,-Bstatic,-lstdc++,-lpthread,-Wl,-Bdynamic" CC=/usr/bin/x86_64-w64-mingw32-gcc CXX=/usr/bin/x86_64-w64-mingw32-g++ FFMPEG_INCLUDE_DIR=/build/ffmpeg/include FFMPEG_LIB_DIR=/build/ffmpeg/lib cargo build --target x86_64-pc-windows-gnu --release

And this is the command cargo spits out:

rustc --crate-name cryptocam_qt --edition=2018 src/main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C opt-level=3 -C embed-bitcode=no -C metadata=080862abb340d8eb -C extra-filename=-080862abb340d8eb --out-dir /build/target/x86_64-pc-windows-gnu/release/deps --target x86_64-pc-windows-gnu -L dependency=/build/target/x86_64-pc-windows-gnu/release/deps -L dependency=/build/target/release/deps --extern anyhow=/build/target/x86_64-pc-windows-gnu/release/deps/libanyhow-e2b1b4a2484185c8.rlib --extern base64=/build/target/x86_64-pc-windows-gnu/release/deps/libbase64-114c89239198e14b.rlib --extern cpp=/build/target/x86_64-pc-windows-gnu/release/deps/libcpp-30cccafa712e0c77.rlib --extern cstr=/build/target/x86_64-pc-windows-gnu/release/deps/libcstr-af51762f59857afd.rlib --extern dirs_next=/build/target/x86_64-pc-windows-gnu/release/deps/libdirs_next-263ba2a428133e5d.rlib --extern hex=/build/target/x86_64-pc-windows-gnu/release/deps/libhex-3a1742e9872e6cd3.rlib --extern lazy_init=/build/target/x86_64-pc-windows-gnu/release/deps/liblazy_init-90c18678a8b28a34.rlib --extern libcryptocam=/build/target/x86_64-pc-windows-gnu/release/deps/liblibcryptocam-52c5efd1863d33db.rlib --extern path_slash=/build/target/x86_64-pc-windows-gnu/release/deps/libpath_slash-6a3fd719200d0aaa.rlib --extern qmetaobject=/build/target/x86_64-pc-windows-gnu/release/deps/libqmetaobject-023534dfb4397d8b.rlib --extern ini=/build/target/x86_64-pc-windows-gnu/release/deps/libini-642c630a136e4570.rlib --extern threadpool=/build/target/x86_64-pc-windows-gnu/release/deps/libthreadpool-8e2fba5ed6305a44.rlib --extern url=/build/target/x86_64-pc-windows-gnu/release/deps/liburl-683d768a46f48ab4.rlib --extern urlencoding=/build/target/x86_64-pc-windows-gnu/release/deps/liburlencoding-fb32cc0db772464e.rlib -L native=/build/target/x86_64-pc-windows-gnu/release/build/cryptocam-qt-bdcaa8b4106f3b9b/out -L '' -l static=rust_cpp_generated -l stdc++ -l Qt5Widgets -l Qt5Gui -l Qt5Core -l Qt5Quick -l Qt5QuickControls2 -l Qt5Qml -L native=/root/.cargo/registry/src/github.com-1ecc6299db9ec823/winapi-x86_64-pc-windows-gnu-0.4.0/lib -L native=/build/target/x86_64-pc-windows-gnu/release/build/ac-ffmpeg-d4c76d5e88805806/out -L native=/build/ffmpeg/bin -L native=/build/target/x86_64-pc-windows-gnu/release/build/qmetaobject-ce21cf4b48acf7c6/out -L /usr/lib/x86_64-linux-gnu

Notice the -L '' which is causing the error. I have no clue where it might be coming from or how to remove it.

Any help is appreciated.

Solved. qmetaobject-rs 0.2.0 updated the build system, so did I and now the error is gone.