[C++] CMAKE_AR is not passed to bzip2 thirdparty dependency

[asfimport]

It seems like the AR or CMAKE_AR variables aren't getting passed for the bzip2 build, which causes if to fail if we're doing a BUNDLED build and ar isn't available in the $PATH (e.g. in a conda environment).

To replicate:

1. Download Arrow and start an interactive shell in a container
   (docker should be fine if you prefer it to podman)

git clone --depth 1 git@github.com:apache/arrow.git
podman run -it --rm -v ./arrow:/arrow:Z docker://ursalab/amd64-ubuntu-18.04-conda-python-3.6:worker bash

2. Build Arrow by running this in in the container:

export ARROW_BUILD_TOOLCHAIN=$CONDA_PREFIX
export ARROW_HOME=$CONDA_PREFIX
export PARQUET_HOME=$CONDA_PREFIX
export ARROW_BUILD_TYPE=DEBUG

cd /arrow
mkdir -p cpp/build
pushd cpp/build

cmake \
      -DCMAKE_BUILD_TYPE=$ARROW_BUILD_TYPE \
      -DCMAKE_INSTALL_PREFIX=$ARROW_HOME \
      -DCMAKE_AR=${AR} \
      -DCMAKE_RANLIB=${RANLIB} \
      -DARROW_WITH_BZ2=ON \
      -DARROW_VERBOSE_THIRDPARTY_BUILD=ON \
      -DARROW_JEMALLOC=OFF \
      -DARROW_SIMD_LEVEL=NONE -DARROW_RUNTIME_SIMD_LEVEL=NONE \
      -DARROW_DEPENDENCY_SOURCE=BUNDLED \
      ..
make
# make[3]: ar: No such file or directory
# make[3]: *** [Makefile:48: libbz2.a] Error 127
# make[2]: *** [CMakeFiles/bzip2_ep.dir/build.make:135: bzip2_ep-prefix/src/bzip2_ep-stamp/bzip2_ep-build] Error 2
# make[1]: *** [CMakeFiles/Makefile2:726: CMakeFiles/bzip2_ep.dir/all] Error 2

In the cmake call above, ARROW_JEMALLOC and the SIMD flags are just to skip compiling irrelevant things.

I think this line in ThirdpartyToolchain.cmake needs to be changed to pass CMAKE_AR.

arrow/cpp/cmake_modules/ThirdpartyToolchain.cmake

Line 2211 in bad8824

set(BZIP2_EXTRA_ARGS "CC=${CMAKE_C_COMPILER}" "CFLAGS=${EP_C_FLAGS}")

Other related issues have also needed to pass CMAKE_RANLIB, in addition to CMAKE_AR. I'm not sure if that applies here.

 
Related: ARROW-4471, ARROW-4831

Edit: added ARROW_BUILD_TYPE above.

Reporter: Karl Dunkle Werner / @karldw
Assignee: Karl Dunkle Werner / @karldw

PRs and other links:

• GitHub Pull Request #11334

_{Note: This issue was originally created as ARROW-14210. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Thanks @karldw! Would you like to make a PR with this fix? cc @kou

[asfimport]

Karl Dunkle Werner / @karldw:
I'm happy to. Two questions:

1. Do we need CMAKE_RANLIB here, or is that irrelevant?
2. Do you want a test for this? If so, could you point me to the file where that test should be added?

[asfimport]

Neal Richardson / @nealrichardson:

1. Do we need CMAKE_RANLIB here, or is that irrelevant?

Not sure, I guess you'll see :)

2. Do you want a test for this? If so, could you point me to the file where that test should be added?

I'm not sure about this either, we have lots of CI already, what's different about this setup exactly? Maybe there's an existing CI job we can modify rather than adding a new one.

[asfimport]

Karl Dunkle Werner / @karldw:

what's different about this setup exactly?
The combination of:

• using a BUNDLED build and
• relying on conda compiler tools, which are assigned nonstandard names

[asfimport]

Kouhei Sutou / @kou:
Could you do it for CMAKE_RANLIB too like

arrow/cpp/cmake_modules/ThirdpartyToolchain.cmake

Lines 636 to 642 in bad8824

	if(CMAKE_AR)
	set(EP_COMMON_TOOLCHAIN ${EP_COMMON_TOOLCHAIN} -DCMAKE_AR=${CMAKE_AR})
	endif()
	if(CMAKE_RANLIB)
	set(EP_COMMON_TOOLCHAIN ${EP_COMMON_TOOLCHAIN} -DCMAKE_RANLIB=${CMAKE_RANLIB})
	endif()

?

We don't need a test for it for now. We will not change bzip2's build code too much. If we make a regression around this, we'll add a test for this case.

[asfimport]

Kouhei Sutou / @kou:
Note that we can use list(APPEND BZIP2_EXTRA_ARGS ...) for this.

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 11334
#11334