[C++] Remove dependency on boost::filesystem

[asfimport]

See ARROW-2196 for details.
boost::filesystem should not be required for base functionality at least (including filesystems, probably).

Reporter: Antoine Pitrou / @pitrou
Assignee: Antoine Pitrou / @pitrou

Related issues:

• [C++] Zero-dependency default core build (is a child of)
• [C++] Consider quarantining platform code with dependency on non-header Boost code (is depended upon by)

PRs and other links:

• GitHub Pull Request #5545

_{Note: This issue was originally created as ARROW-6613. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
boost::filesystem is used in conjuction with boost::process for testing Flight and S3FS. I don't think it's reasonable to reimplement boost::process.

Still, we can try to make boost::filesystem unnecessary if tests are not built.

[asfimport]

Antoine Pitrou / @pitrou:
@wesm We should perhaps discuss if it's really useful to have bare-bones no-boost build. We will probably end up copy-pasting some boost code along the way.

[asfimport]

Wes McKinney / @wesm:
I think we should remove Boost as a dependency of the core build. Which may mean not building certain modules (like the code in src/arrow/filesystem) by default. I think that should make things easier

[asfimport]

Antoine Pitrou / @pitrou:
I've started looking into this. There's some non-trivial Windows-specific code in boost::filesystem to handle reparse points and symlinks. It feels a bit counter-productive to copy/paste it without knowing exactly what it does.

[asfimport]

Wes McKinney / @wesm:
I would suggest adding a ARROW_FILESYSTEM option, setting it to off by default, then handling the remaining usages of Boost in the core library-only build.

I think it's fine to have boost::filesystem in src/arrow/filesystem. People who are making use of this functionality are probably more OK with accepting additional build dependencies. I would mainly like this stuff to be out of the way of people who are only using Array / ArrayBuilder / RecordBatch and IPC read/write tools

[asfimport]

Antoine Pitrou / @pitrou:
Much of the functionality is in the core build (see util/io_util.h).

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 5545
#5545