Clearly document what is carried over in multi-stage builds about docs HOT 1 OPEN

Information on whether things like ARG, WORKDIR, USER etc carry over when using FROM previous-stage is not clearly indicated on the multi-stage builds page.

AFAIK, it's the same as if you extended an image via FROM without a multi-stage build.

You should be able to confirm any of those concerns locally fairly easily yourself, but sure it may be worthwhile to clarify that to the reader.

Not sure why you'd think ARG to carry over? The docs for this instruction are pretty good, you can define ARG prior to a FROM, and it'll be available in the scope of that instruction, anything after that FROM is then in a "stage" (regardless of single or multi), you need to use ARG again to make any build arg provided as a temporary ENV again, for multi-stage that likewise means each FROM requires you to declare ARG within it's own stage that you want to use it.

from docs.