Failure on recent julia master

[thofma]

We observed CxxWrap.jl failing on recent julia master builds with the following error:

C++ exception while wrapping module StdLib: invalid subtyping in definition of StdString with supertype CppBasicString
ERROR: LoadError: invalid subtyping in definition of StdString with supertype CppBasicString
in expression starting at /home/runner/.julia/packages/CxxWrap/OcN1Z/src/StdLib.jl:1
in expression starting at /home/runner/.julia/packages/CxxWrap/OcN1Z/src/CxxWrap.jl:1
ERROR: LoadError: Failed to precompile CxxWrap [1f15a43c-97ca-5a2a-ae31-89f07a497df4] to /home/runner/.julia/compiled/v1.7/CxxWrap/jl_ncNARQ.

CC: @benlorenz

[benlorenz]

I did a little bit of experimenting and found the following:

• It started with move some more shared properties to TypeName JuliaLang/julia#40741 where some internal data type stuff was moved around
• It disappears when building libcxxwrap-julia against julia master and using an override. So it is more a binary incompatibility when using binaries built for 1.6 on nightly.
  (With that override: Testing CxxWrap tests passed)

[thofma]

Since master is a moving target, not sure how we should handle this in Yggdrasil. Feature freeze for julia 1.7 already happened, so the new version should be "around the corner". So we could either add the recipes for 1.7 and hope that nothing changes, or just wait for the official julia release.

[eschnett]

I would add the recipes for 1.7 now. This gives people the time to test before the release, so that possible bug are at least known at release time.

[thofma]

There was a discussion on slack and the consensus was that we do a libjulia_jll for 1.7 with whatever 1.7 there is now (beta2?). I think @fingolfin was planning to look at this.

[fingolfin]

I think this is resolved now?

[fingolfin]

@barche I think this can be closed

[barche]

Yes, support for Julia 1.7 (and 1.8 I think) is in Yggdrasil.