Update mlpack to latest stable version (4.8.0).

[rcurtin]

Simple version bump, hopefully everything should build clean here. :)

No major changes in upstream functionality (at least from the Julia perspective).

[rcurtin]

Oh. I lied. I forgot that some of the Julia interface actually did change. I'll fix this tomorrow, I know what's wrong.

[rcurtin]

The mingw32 error looks like this one:

https://sourceforge.net/p/mingw-w64/bugs/737/

which is an upstream mingw32 error, not an mlpack issue. (Older versions of mlpack didn't trigger this because they didn't use std::filesystem::path for handling paths.)

What is the "right" strategy to proceed here? Disable mingw32 build? Upgrade mingw32 compiler in Yggdrasil? Find some awful workaround? Let me know what you think.

[giordano]

https://buildkite.com/julialang/yggdrasil/builds/30396#019edd14-6112-4090-b0bd-410499a7cc5b/L3075

[00:54:30] In file included from /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/filesystem:37,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/base.hpp:28,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/prereqs.hpp:15,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/bindings/julia/julia_util.cpp:13:
[00:54:30] /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/fs_path.h: In member function ‘std::filesystem::__cxx11::path& std::filesystem::__cxx11::path::operator/=(const std::filesystem::__cxx11::path&)’:
[00:54:30] /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/fs_path.h:237:47: error: no match for ‘operator!=’ (operand types are ‘std::filesystem::__cxx11::path’ and ‘std::filesystem::__cxx11::path’)
[00:54:30]     || (__p.has_root_name() && __p.root_name() != root_name()))
[00:54:30]                                ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~
[00:54:30] In file included from /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/stl_algobase.h:64,
[00:54:30]                  from /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/specfun.h:45,
[00:54:30]                  from /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/cmath:1892,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/base.hpp:17,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/prereqs.hpp:15,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/bindings/julia/julia_util.cpp:13:
[00:54:30] /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/stl_pair.h:456:5: note: candidate: ‘template<class _T1, class _T2> constexpr bool std::operator!=(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)’
[00:54:30]      operator!=(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
[00:54:30]      ^~~~~~~~
[00:54:30] /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/stl_pair.h:456:5: note:   template argument deduction/substitution failed:
[00:54:30] In file included from /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/filesystem:37,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/base.hpp:28,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/prereqs.hpp:15,
[00:54:30]                  from /workspace/srcdir/mlpack-4.8.0/src/mlpack/bindings/julia/julia_util.cpp:13:
[00:54:30] /opt/i686-w64-mingw32/i686-w64-mingw32/include/c++/8.1.0/bits/fs_path.h:237:60: note:   ‘std::filesystem::__cxx11::path’ is not derived from ‘const std::pair<_T1, _T2>’
[00:54:30]     || (__p.has_root_name() && __p.root_name() != root_name()))
[00:54:30]                                                             ^

@Keno is it possible this is related to your recent changes?

[Keno]

Never say never, but I don't think so - we reverted the rootfs bump, so Yggdrasil bumps should be unaffected.

[Keno]

Try forcing a later gcc version.

[rcurtin]

Thanks @Keno and @giordano!