[C++] Unbound scan projection expression leads to all fields being loaded

[asfimport]

If a projection expression is unbound then we should bind it to the (augmented) dataset schema and carry on. Instead it appears we are interpreting "unbound expression" as "nothing set at all" and loading all fields.

Reporter: Weston Pace / @westonpace
Assignee: Vibhatha Lakmal Abeykoon / @vibhatha

Related issues:

• [R][C++] Regression: big performance hit after removing schema binding (fixes)

PRs and other links:

• GitHub Pull Request #14264

_{Note: This issue was originally created as ARROW-17556. Please see the migration documentation for further details.}

[asfimport]

Weston Pace / @westonpace:
Issue resolved by pull request 14264
#14264