The quick-start example doesn't compile on Debian10 64 bit (run is WLS Windows-10 from VisualStudioCode)

[IvankoB]

on any g++ v8.3 compiler (g++, c89-gcc, c99-gcc) choosen and any C++ standard (CMAKE_CXX_STANDARD 98 / 11 / 14).

Eigen3 v 3.3.7-1 is installed from within Debian :
apt install libeigen3-dev

The project is really needed for very old (Debian6 which can't be upgraded on the targets) LINUX (where builds well with gcc-4.4.5 but many "Parameter .. not used" warnings issued).
DEBIAN10 WLS in Windows10 is only tried for develepment convinience reasons as long as the Eigen vesion is 3.3.7-1 in both DEBIAN6 and DEBIAN10.

The build log :

[main] Building folder: uzsearch uzsearch
[build] Starting build
[proc] Executing command: /usr/bin/cmake --build /home/pochta/myprojects/uzsearch/build --config Debug --target uzsearch -- -j 6
[build] [ 50%] Building CXX object CMakeFiles/uzsearch.dir/main.cpp.o
[build] In file included from /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback/VerboseCallback.h:8,
[build] from /home/pochta/myprojects/GITROOT/MiniDNN/include/MiniDNN.h:34,
[build] from /home/pochta/myprojects/uzsearch/main.cpp:1:
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback/../Network.h: In instantiation of ‘bool MiniDNN::Network::fit(MiniDNN::Optimizer&, const Eigen::MatrixBase&, const Eigen::MatrixBase&, int, int, int) [with DerivedX = Eigen::Matrix<double, -1, 2>; DerivedY = Eigen::Matrix<double, -1, 2>]’:
[build] /home/pochta/myprojects/uzsearch/main.cpp:48:36: required from here
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback/../Network.h:477:21: error: call of overloaded ‘pre_training_batch(MiniDNN::Network*, Eigen::Matrix<double, -1, 2>&, Eigen::Matrix<double, -1, 2>&)’ is ambiguous
[build] m_callback->pre_training_batch(this, x_batches[i], y_batches[i]);
[build] ^~~~~~~~~~
[build] In file included from /home/pochta/myprojects/GITROOT/MiniDNN/include/MiniDNN.h:33,
[build] from /home/pochta/myprojects/uzsearch/main.cpp:1:
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback.h:49:22: note: candidate: ‘virtual void MiniDNN::Callback::pre_training_batch(const MiniDNN::Network*, const Matrix&, const Matrix&)’
[build] virtual void pre_training_batch(const Network* net, const Matrix& x,
[build] ^~~~~~~~~~~~~~~~~~
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback.h:51:22: note: candidate: ‘virtual void MiniDNN::Callback::pre_training_batch(const MiniDNN::Network*, const Matrix&, const IntegerVector&)’
[build] virtual void pre_training_batch(const Network* net, const Matrix& x,
[build] ^~~~~~~~~~~~~~~~~~
[build] In file included from /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback/VerboseCallback.h:8,
[build] from /home/pochta/myprojects/GITROOT/MiniDNN/include/MiniDNN.h:34,
[build] from /home/pochta/myprojects/uzsearch/main.cpp:1:
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback/../Network.h:481:21: error: call of overloaded ‘post_training_batch(MiniDNN::Network*, Eigen::Matrix<double, -1, 2>&, Eigen::Matrix<double, -1, 2>&)’ is ambiguous
[build] m_callback->post_training_batch(this, x_batches[i], y_batches[i]);
[build] ^~~~~~~~~~
[build] In file included from /home/pochta/myprojects/GITROOT/MiniDNN/include/MiniDNN.h:33,
[build] from /home/pochta/myprojects/uzsearch/main.cpp:1:
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback.h:55:22: note: candidate: ‘virtual void MiniDNN::Callback::post_training_batch(const MiniDNN::Network*, const Matrix&, const Matrix&)’
[build] virtual void post_training_batch(const Network* net, const Matrix& x,
[build] ^~~~~~~~~~~~~~~~~~~
[build] /home/pochta/myprojects/GITROOT/MiniDNN/include/Callback.h:57:22: note: candidate: ‘virtual void MiniDNN::Callback::post_training_batch(const MiniDNN::Network*, const Matrix&, const IntegerVector&)’
[build] virtual void post_training_batch(const Network* net, const Matrix& x,
[build] ^~~~~~~~~~~~~~~~~~~
[build] make[3]: *** [CMakeFiles/uzsearch.dir/build.make:63: CMakeFiles/uzsearch.dir/main.cpp.o] Error 1
[build] make[2]: *** [CMakeFiles/Makefile2:585: CMakeFiles/uzsearch.dir/all] Error 2
[build] make[1]: *** [CMakeFiles/Makefile2:597: CMakeFiles/uzsearch.dir/rule] Error 2
[build] make: *** [Makefile:359: uzsearch] Error 2
[build] Build finished with exit code 2

It also fails in runtime with the only instantiation (all the latter code is commented): Matrix x = Matrix::Random(400, 100);
with the run log :

pochta@Vano-Home:~/myprojects/uzsearch$ /home/pochta/myprojects/uzsearch/build/uzsearch
uzsearch: /usr/include/eigen3/Eigen/src/Core/util/XprHelper.h:110: Eigen::internal::variable_if_dynamic<T, Value>::variable_if_dynamic(T) [with T = long int; int Value = 2]: Assertion `v == T(Value)' failed.
Aborted (core dumped)