bootstrap: Ensure host documentation is built before tarball is created

`run_default_doc_steps()` is called to ensure the documentation is built
by `Docs::run()` and it should build the documentation if it isn't
already built.

When running the `install src` command I'm seeing failures as the
`builder.doc_out(host)` directory does not exist. This is because
`match_paths_to_steps_and_run()` doesn't actually build any
documentation as the `paths.is_empty()` causes an early return. This
results in install failures as the `*/doc` src directory doesn't exist.

This patch passes the paths to `run_host_step_descriptions()` when building
documentation to ensure it is correctly built.

This fixes installing the Rust source code in OpenEmbedded.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

Author: alistair23

src/bootstrap/src/core/build_steps/dist.rs

@@ -83,7 +83,7 @@ impl Step for Docs {
         // FIXME: explicitly enumerate the steps that should be executed here, and gather their
         // documentation, rather than running all default steps and then read their output
         // from a shared directory.
-        builder.run_default_doc_steps();
+        builder.run_host_default_doc_steps();
 
         let dest = "share/doc/rust/html";
 

src/bootstrap/src/core/builder/mod.rs

@@ -1117,6 +1117,11 @@ impl<'a> Builder<'a> {
         self.run_step_descriptions(&Builder::get_step_descriptions(self.kind), &self.paths);
     }
 
+    /// Run all default documentation steps to build documentation.
+    pub fn run_host_default_doc_steps(&self) {
+        self.run_step_descriptions(&Builder::get_step_descriptions(Kind::Doc), &self.paths);
+    }
+
     /// Run all default documentation steps to build documentation.
     pub fn run_default_doc_steps(&self) {
         self.run_step_descriptions(&Builder::get_step_descriptions(Kind::Doc), &[]);