Update arrow for 2.0.0

[nealrichardson]

Changes:

• S3 enabled and aws-sdk-cpp added as a dependency (this will not be added to rtools-backports)
• Mimalloc enabled (the Vista compatibility patch has been released)
• Add some new USE_SHARED=OFF flags

[jeroen]

If you use -DARROW_SNAPPY_USE_SHARED=OFF can you remove mingw-w64-snappy from the dependencies? Perhaps also other dependencies that you no longer use?

[nealrichardson]

Those _USE_SHARED=OFF flags just say to look for the static version of those dependencies, not that they're not dependencies anymore.

[jeroen]

Are you sure? Typically SHARED=OFF means to build a vendored version of the library.

[nealrichardson]

We govern that by the DEPENDENCY_SOURCE=BUNDLED|SYSTEM flags, and these are all SYSTEM. You can see in the build logs that there are no e.g. snappy_ep or other cmake external projects being built, they're coming from the system packages.

These USE_SHARED flags came from this commit, which explains what they're for: apache/arrow@81d3f26

[jeroen]

By the way, does this version of arrow assume hw features on the machine of the user, or does this get detected at runtime?

The CRAN winbuilder runs very old hardware, there are some other packages that crash on CRAN Winbuilder because they enable SIMD features that may be supported in the rtools40 compilers, but actually not available on the CRAN hardware (at least I think that is the problem): https://cran.r-project.org/web/packages/RcppXsimd/index.html

[nealrichardson]

AVX512 is disabled on mingw always: https://github.com/apache/arrow/blob/master/cpp/cmake_modules/SetupCxxFlags.cmake#L62

So the inaccurate SIMD detection we patched in autobrew won't matter here.

[jeroen]

Thanks! All seems to work but I recommend you have a look at the -Wmaybe-uninitialized compiler warnings shown in the CI.

[nealrichardson]

Thanks. We need to set up better CI for that, I feel like I find more of those warnings every time I look.

[jeroen]

You just need to add -Werror to CXXFLAGS in your CI, then it will fail for compiler warnings.

[nealrichardson]

I thought I had already done that though. Maybe I only set it for the R bindings, not the C++ library build? In any case, thanks, will take care of these.