tree bdeb937d2cfcc13ce966f3a70dd104df775cbf5f
parent 00a2c9e052b96fe1b1a27f838969284337aa494f
author Greg Estren <gregestren@gmail.com> 1556230692 -0700
committer Copybara-Service <copybara-worker@google.com> 1556230763 -0700

Clarify why `cfg` is mandatory for `executable=True` attributes.

I was originally considering removing `cfg = "target"` support in the name of API cleanup, since that's a semantic no-op. But the reasoning is fair for when `cfg` is mandatory (shared in a Google doc by @laurentlb):

> "When an input is executable, we often want to run it on the host. So I suggest that cfg is mandatory when input is executable".

But I don't think we should set `cfg = "target"` casually when it's not helpful - that'll just litter code bases. I tried to address these issues in this PR.

Also note, for posterity, that `cfg = "host"` is due for deprecation: https://github.com/bazelbuild/proposals/blob/master/designs/2019-02-12-execution-transitions.md

Closes #8025.

PiperOrigin-RevId: 245316460