Rollup merge of #111955 - jyn514:step-refactors, r=clubby789

bootstrap: Various Step refactors

This ended up being a bunch of only somewhat related changes, sorry :sweat: on the bright side, they're all fairly small  and well-commented in the commit messages.

- Document `ShouldRun::crates`

- Switch Steps from crates to crate_or_deps where possible

    and document why the single remaining place can't switch

- Switch doc::{Std, Rustc} to `crate_or_deps`

    Previously they were using `all_krates` and various hacks to determine
    which crates to document. Switch them to `crate_or_deps` so `ShouldRun`
    tells them which crate to document instead of having to guess.

    This also makes a few other refactors:
    - Remove the now unused `all_krates`; new code should only use
      `crate_or_deps`.
    - Add tests for documenting Std
    - Remove the unnecessary `run_cargo_rustdoc_for` closure so that we only
      run cargo once
    - Give a more helpful error message when documenting a no_std target
    - Use `builder.msg` in the Steps instead of `builder.info`

- Extend `msg` and `description` to work with any subcommand

    Previously `description` only supported `Testing` and `Benchmarking`,
    and `msg` gave weird results for `doc` (it would say `Docing`).

- Add a `make_run_crates` function and use it Rustc and Std

    This fixes the panic from the previous commit.

- Allow checking individual crates

    This is useful for profiling metadata generation.

    This comes very close to removing all_krates, but doesn't quite -
    there's one last usage left in `doc`. This is fixed in a later commit.

- Give a more helpful error when calling `cargo_crates_in_set` for an alias

    Before:
    ```
    thread 'main' panicked at 'no entry found for key', builder.rs:110:30
    ```

    After:
    ```
    thread 'main' panicked at 'missing crate for path library', check.rs:89:26
    ```

1 files changed, 7 insertions, 7 deletions

diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 44cd84be705..960abb31b20 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -101,7 +101,7 @@ impl Step for CrateBootstrap {
         );
         builder.info(&format!(
             "{} {} stage0 ({})",
-            builder.kind.test_description(),
+            builder.kind.description(),
             path,
             bootstrap_host,
         ));
@@ -220,7 +220,7 @@ impl Step for HtmlCheck {
         }
         // Ensure that a few different kinds of documentation are available.
         builder.default_doc(&[]);
-        builder.ensure(crate::doc::Rustc { target: self.target, stage: builder.top_stage });
+        builder.ensure(crate::doc::Rustc::new(builder.top_stage, self.target, builder));
 
         try_run(builder, builder.tool_cmd(Tool::HtmlChecker).arg(builder.doc_out(self.target)));
     }
@@ -886,11 +886,11 @@ impl Step for RustdocJSStd {
                     command.arg("--test-file").arg(path);
                 }
             }
-            builder.ensure(crate::doc::Std {
-                target: self.target,
-                stage: builder.top_stage,
-                format: DocumentationFormat::HTML,
-            });
+            builder.ensure(crate::doc::Std::new(
+                builder.top_stage,
+                self.target,
+                DocumentationFormat::HTML,
+            ));
             builder.run(&mut command);
         } else {
             builder.info("No nodejs found, skipping \"tests/rustdoc-js-std\" tests");