Missing iterator definition

[xrl]

Describe the bug

My build.rs script fails because the iterator type isn't available. Reproduced on both Mac OS X and Ubuntu Linux.

To Reproduce

• Isolated reproduction with failing build in github actions:
  • https://github.com/rdkit-rs/rdkit-autocxx-repro/
  • https://github.com/rdkit-rs/rdkit-autocxx-repro/actions/runs/6395848454/job/17360416383

You'll probably be curious what the inputs to this build are and what the auto-generating bindings look like

• autocxxgen_ffi.h, gen0.cxx, ROMol.h are in this gist: https://gist.github.com/xrl/2a593e6e546c25d5afa58e6e7ab14c3d

Expected behavior

I would have expected the bindings to fail because of something I defined but it looks like autocxx is pulling in funny code from the headers?

Additional context

I have build bindings with cxx-rs successfully here: https://github.com/rdkit-rs/rdkit-sys

And the errors from the repro are a little different on my OS X setup but similar in spirit: https://gist.github.com/xrl/91d94c3bef8b04a64985d4444c8604f2

namely:

warning: In file included from /Users/xlange/code/assaydepot/rdkit-autocxx-repro/target/debug/build/rdkit-autocxx-repro-af359ecff0c3ad28/out/autocxx-build-dir/cxx/gen0.cxx:3:
warning: /Users/xlange/code/assaydepot/rdkit-autocxx-repro/target/debug/build/rdkit-autocxx-repro-af359ecff0c3ad28/out/autocxx-build-dir/include/autocxxgen_ffi.h:37:31: error: use of undeclared identifier 'iterator'; did you mean 'boost_swap_impl::iterator'?
warning: typedef std::reverse_iterator<iterator> std_reverse_iterator_iterator_AutocxxConcrete;
warning:                               ^~~~~~~~
warning:                               boost_swap_impl::iterator
warning: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/v1/__iterator/iterator.h:24:57: note: 'boost_swap_impl::iterator' declared here
warning: struct _LIBCPP_TEMPLATE_VIS _LIBCPP_DEPRECATED_IN_CXX17 iterator
warning:                                                         ^
warning: In file included from /Users/xlange/code/assaydepot/rdkit-autocxx-repro/target/debug/build/rdkit-autocxx-repro-af359ecff0c3ad28/out/autocxx-build-dir/cxx/gen0.cxx:3:

[adetaylor]

Thanks - could you try to come up with a minimal test case using these instructions?

[xrl]

It looks like I need to pass in the right version of c++ to get this compiling but I'm not sure how to pass that in:

autocxx-reduce --clang-arg='-std=c++17' --problem "use of undeclared identifier 'iterator'" file -d "safety!(unsafe_ffi)" -d 'generate_ns("RDKit")' -I /opt/homebrew/include -I /opt/homebrew/include/rdkit --header 'GraphMol/ROMol.h' > creduce-stream.txt

Error:   × the include_cpp! macro couldn't be expanded into Rust bindings to C++:
  │ Bindgen was unable to generate the initial .rs bindings for this file.
  │ This may indicate a parsing problem with the C++ headers.

In file included from /var/folders/mc/3pj1vp8s239fn610rbv56f440000gp/T/.tmpX47vgY/listing.h:1:
In file included from /opt/homebrew/include/rdkit/GraphMol/ROMol.h:39:
In file included from /opt/homebrew/include/rdkit/RDGeneral/types.h:28:
/opt/homebrew/include/rdkit/RDGeneral/Dict.h:261:25: error: no template named 'is_same_v' in namespace 'std'; did you mean 'is_same'?
    static_assert(!std::is_same_v<T, std::string_view>,
                   ~~~~~^~~~~~~~~
                        is_same

I don't see this error when I set the C++ version in the autocxx builder like this:

    let mut builder = autocxx_build::Builder::new("src/main.rs", &include_paths)
        .extra_clang_args(&["-std=c++17"])
        .build()
        .unwrap();

Thoughts on how to forward the c++20 version in to the autocxx-reduce tooling?

[xrl]

@adetaylor I would appreciate some guidance. or perhaps there's a good spot to reach out to the community?

[adetaylor]

Yeah, sorry for the lack of response. I don't know what's going wrong with autocxx-reduce absorbing that clang arg.

autocxx-reduce causes problems of one kind or another for about 50% of the people who try to use it. It usually requires a little massaging itself to behave, so I'm not surprised you've encountered problems.

Unfortunately though I will need a minimized version of the C++ headers to be able to investigate this problem. I know from bitter experience that it takes multiple hours to reproduce problems which are not minimized, and I don't have hours spare at the moment - possibly after the holiday season.

I'd suggest your best bet is to struggle through getting autocxx-reduce to work (on Linux). Here's where it ought to be doing something with those arguments.

[xrl]

OK, I will work on a linux environment and rule out the os x flavored stuff. Thanks for the tip 👌