Remove boost dependency

[codereport]

Once we remove Boost filesystem dependency and use std::filesystem, we can remove the boost dependency.

This change requires dropping support for GCC < 9.

[kkraus14]

Can you remove boost from the conda recipes / environments / build instructions as well?

• https://github.com/rapidsai/cudf/blob/branch-0.20/conda/recipes/libcudf/meta.yaml#L42
• https://github.com/rapidsai/cudf/blob/branch-0.20/conda/environments/cudf_dev_cuda11.0.yml#L51 (can drop the 10.x environment files while you're at it)
• https://github.com/rapidsai/integration/blob/branch-0.19/conda/recipes/versions.yaml#L35-L36
• https://github.com/rapidsai/integration/blob/branch-0.19/conda/recipes/rapids-build-env/meta.yaml#L46-L47
• https://github.com/rapidsai/cudf/blob/branch-0.20/java/README.md#build-from-source

[davidwendt]

Boost is also installed in the docker_build Docker file

cudf/docker_build/Dockerfile

Lines 43 to 45 in 7ad07b4

	libboost-filesystem-dev \
	libboost-system-dev \
	libboost-regex-dev \

I'm not sure if the libboost-system-dev and libboost-regex-dev are needed for some other purpose.

[codereport]

rerun tests

[jlowe]

If LICENSE-bundled is being deleted then the corresponding <resource> node needs to be removed in java/pom.xml

[jrhemstad]

rerun tests

[harrism]

07:16:12 FAILED: CMakeFiles/cudf.dir/src/jit/cache.cpp.o 
07:16:13 ccache /usr/bin/g++ -DCUDF_VERSION=0.20.0 -DCUFILE_FOUND -DJITIFY_PRINT_LOG=0 -DJITIFY_USE_CACHE -DSPDLOG_ACTIVE_LEVEL=SPDLOG_LEVEL_INFO -DTHRUST_DEVICE_SYSTEM=THRUST_DEVICE_SYSTEM_CUDA -DTHRUST_HOST_SYSTEM=THRUST_HOST_SYSTEM_CPP -Dcudf_EXPORTS -I_deps/jitify-src -I_deps/libcudacxx-src/include -I../include -Iinclude -I../src -I_deps/thrust-src -I_deps/thrust-src/dependencies/cub -isystem $PREFIX/include -isystem $BUILD_PREFIX/include -isystem /usr/local/cuda/include -isystem /usr/local/cuda/lib64 -O3 -DNDEBUG -fPIC -Wall -Werror -Wno-unknown-pragmas -Wno-error=deprecated-declarations -Wno-deprecated-declarations -pthread -std=gnu++1z -MD -MT CMakeFiles/cudf.dir/src/jit/cache.cpp.o -MF CMakeFiles/cudf.dir/src/jit/cache.cpp.o.d -o CMakeFiles/cudf.dir/src/jit/cache.cpp.o -c ../src/jit/cache.cpp
07:16:13 ../src/jit/cache.cpp:22:10: fatal error: filesystem: No such file or directory
07:16:13  #include <filesystem>
07:16:13           ^~~~~~~~~~~~
07:16:13 compilation terminated.

So it appears that gcc is not finding the filesystem header. What is weird to me is this: -std=gnu++1z instead of -std=c++17.

[kkraus14]

cmake / conda lgtm

[codecov]

Codecov Report

Merging #7932 (db60e37) into branch-0.20 (51336df) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           branch-0.20    #7932      +/-   ##
===============================================
- Coverage        82.88%   82.88%   -0.01%     
===============================================
  Files              103      104       +1     
  Lines            17668    17907     +239     
===============================================
+ Hits             14645    14843     +198     
- Misses            3023     3064      +41     

Impacted Files	Coverage Δ
python/cudf/cudf/core/tools/datetimes.py	80.42% <0.00%> (-4.11%)	⬇️
python/cudf/cudf/core/column/decimal.py	90.20% <0.00%> (-2.72%)	⬇️
python/cudf/cudf/core/column/datetime.py	88.03% <0.00%> (-1.88%)	⬇️
python/cudf/cudf/core/column/struct.py	94.73% <0.00%> (-1.56%)	⬇️
python/cudf/cudf/utils/dtypes.py	82.20% <0.00%> (-1.24%)	⬇️
python/dask_cudf/dask_cudf/groupby.py	91.28% <0.00%> (-0.88%)	⬇️
python/cudf/cudf/core/series.py	91.17% <0.00%> (-0.56%)	⬇️
python/cudf/cudf/core/index.py	92.52% <0.00%> (-0.55%)	⬇️
python/cudf/cudf/core/column/column.py	88.20% <0.00%> (-0.44%)	⬇️
python/cudf/cudf/core/column/lists.py	86.98% <0.00%> (-0.43%)	⬇️
... and 28 more

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[codereport]

@gpucibot merge