use --host-platform instead of --target-platform

[beckermr]

@isuruf would like to see us use --host-platform instead of --target-platform when calling rattler-build.

We should add an alias for now.

xref: conda-forge/conda-smithy#2070 (comment)

[wolfv]

This goes beyond just the CLI argument: target_platform is used throughout the build process and is even part of the hash. It's part of every variant (e.g. you can always do if: target_platform == build_platform etc.

I think renaming it is relatively breaking at this point.

We could still alias it, but the question would be if we want to phase out target_platform over the long run.

Personally it doesn't bother me so much. I am a little sad that it only comes up now (after rattler-build has been around for quite some time) - would have been cool to discuss this earlier (or as part of a CEP).

[isuruf]

as part of a CEP

We did discuss the in the case of requirements where we went with build and host, but not exactly _platform.

I'm not saying we remove target_platform. In almost all cases host_platform == target_platform and differs only in the case of compilers.
We should use host_platform to mean the platform of host and build_platform to mean the platform of build which makes it clear.
target_platform is the platform where the code generated by the compiler can run on instead of the platform where the compiler is run.

[wolfv]

Fixed in #1087