GH-36820: [C++] Remove a needless return in Acero ScanNode::AddScanTasks

[mapleFU]

Rationale for this change

ScanNode::AddScanTasks has multiple return value. This patch remove the latter one.

What changes are included in this PR?

Just remove some code.

Are these changes tested?

no

Are there any user-facing changes?

no

• Closes: [C++] Acero: ScanNode::AddScanTasks has unreached return value #36820

[github-actions]

⚠️ GitHub issue #36820 has been automatically assigned in GitHub to PR creator.

[kou]

(I'm not sure the details of this code too.)

If we don't need to return list_and_scan_done, it seems that we can remove all list_and_scan_done related codes too.

[mapleFU]

Let me wait for weston's idea...Actually I'm not sure whether we need to return OK() or list_and_scan_done

[mapleFU]

@westonpace would you mind take a look? Just two line fix

[westonpace]

Thanks. I changed the need for this future in #32768 but it was very clumsy of me to leave this return statement here. Sorry.

You could probably change this method to return void but the method will also hopefully be going away entirely as part of #35889 so I'm fine if you want to stick with this minimal change.

[westonpace]

And yes, we should be able to remove list_and_scan_done entirely but it is not too important since this method is going away.

[mapleFU]

Just want to remove it because I seen this while reading the code. If you think it's not neccessary, feel free to close this patch :-)
I'll try to remove list_and_scan_done later

[mapleFU]

Close this issue and wait for #35889 to be merged :-)