I've got rules_ocaml working pretty well; now I'm trying to add rules_coq.
It works fine (I can build and run coqtop) until I try to put the `coqc` compiler in a toolchain. The problem then is that a bunch of stuff gets built twice, and in particular a lib that is a dependency of both the `coqc` compiler and the things the compiler builds. I end up with a very OCamlish error when I try to use (toolchainized) `coqc` to compile a coq module, e.g.
`Error: Dynlink error: interface mismatch on Gramlib`
since the output of the OCaml compiler contains metadata indicating how it was built, so it can see two different builds of Gramlib were used and barfs.
I believe the problem is that some of my deps are built on the host platform and also on (presumably) the execution platform. Example log msgs:
```
SUBCOMMAND: # //kernel:_GenOpcodeFiles [action 'native compiling ocaml_module: coq//kernel:_GenOpcodeFiles', configuration: dc73254f32901a6e5c6dd8ffc7359cbf52b48985034ebda0a6dc2cd38ac6974f, execution platform: @local_config_platform//:host]
```
and
```
SUBCOMMAND: # //kernel:_GenOpcodeFiles [action 'native compiling ocaml_module: coq//kernel:_GenOpcodeFiles [for host]', configuration: 66ba5f67c7587007cdeadf15db71cd651aafe5d6039fb4390272ae283c6b9db1, execution platform: @local_config_platform//:host]
```
Note the `[for host]` bit in the second example.
How can I get everything to build one way, without dups? I've added `cfg="exec"` to all my executable attribs, and `exec_tools` to my genrules, but I'm still seeing lots of stuff built with `[for host]`. What causes that?
Some of my actions use `ctx.actions.run_shell` to copy/rename source files. I don't see any way to set `cfg="exec"` for those; is that what is causing the transition to host platform?
Thanks,
Gregg