message: Add warning when mixing -Zbuild-std with --build-plan.
diff: @@ -309,6 +309,11 @@ pub fn compile_ws<'a>(
  let (mut packages, resolve_with_overrides) = resolve;
  let std_resolve = if let Some(crates) = &config.cli_unstable().build_std {
  + if build_config.build_plan {
  + config
  + .shell()
  + .warn("-Zbuild-std does not currently fully support --build-plan")?;
  + }
  if build_config.requested_target.is_none() {
  // TODO: This should eventually be fixed. Unfortunately it is not
  // easy to get the host triple in BuildConfig. Consider changing
  