Permit getting stage 0 rustdoc

This allows us to e.g. test compiletest, including doctests, in stage 0
without building a fresh compiler and rustdoc.

src/bootstrap/builder.rs

@@ -668,28 +668,27 @@ impl<'a> Builder<'a> {
             .map(|entry| entry.path())
     }
 
-    pub fn rustdoc(&self, host: Interned<String>) -> PathBuf {
-        self.ensure(tool::Rustdoc { host })
+    pub fn rustdoc(&self, compiler: Compiler) -> PathBuf {
+        self.ensure(tool::Rustdoc { compiler })
     }
 
-    pub fn rustdoc_cmd(&self, host: Interned<String>) -> Command {
+    pub fn rustdoc_cmd(&self, compiler: Compiler) -> Command {
         let mut cmd = Command::new(&self.out.join("bootstrap/debug/rustdoc"));
-        let compiler = self.compiler(self.top_stage, host);
         cmd.env("RUSTC_STAGE", compiler.stage.to_string())
             .env("RUSTC_SYSROOT", self.sysroot(compiler))
             // Note that this is *not* the sysroot_libdir because rustdoc must be linked
             // equivalently to rustc.
             .env("RUSTDOC_LIBDIR", self.rustc_libdir(compiler))
             .env("CFG_RELEASE_CHANNEL", &self.config.channel)
-            .env("RUSTDOC_REAL", self.rustdoc(host))
+            .env("RUSTDOC_REAL", self.rustdoc(compiler))
             .env("RUSTDOC_CRATE_VERSION", self.rust_version())
             .env("RUSTC_BOOTSTRAP", "1");
 
         // Remove make-related flags that can cause jobserver problems.
         cmd.env_remove("MAKEFLAGS");
         cmd.env_remove("MFLAGS");
 
-        if let Some(linker) = self.linker(host) {
+        if let Some(linker) = self.linker(compiler.host) {
             cmd.env("RUSTC_TARGET_LINKER", linker);
         }
         cmd
@@ -751,7 +750,7 @@ impl<'a> Builder<'a> {
                 // This is the intended out directory for compiler documentation.
                 my_out = self.compiler_doc_out(target);
             }
-            let rustdoc = self.rustdoc(compiler.host);
+            let rustdoc = self.rustdoc(compiler);
             self.clear_if_dirty(&my_out, &rustdoc);
         } else if cmd != "test" {
             match mode {
@@ -897,7 +896,7 @@ impl<'a> Builder<'a> {
             .env(
                 "RUSTDOC_REAL",
                 if cmd == "doc" || cmd == "rustdoc" || (cmd == "test" && want_rustdoc) {
-                    self.rustdoc(compiler.host)
+                    self.rustdoc(compiler)
                 } else {
                     PathBuf::from("/path/to/nowhere/rustdoc/not/required")
                 },

src/bootstrap/dist.rs

@@ -479,7 +479,7 @@ impl Step for Rustc {
             t!(fs::create_dir_all(image.join("bin")));
             builder.cp_r(&src.join("bin"), &image.join("bin"));
 
-            builder.install(&builder.rustdoc(compiler.host), &image.join("bin"), 0o755);
+            builder.install(&builder.rustdoc(compiler), &image.join("bin"), 0o755);
 
             // Copy runtime DLLs needed by the compiler
             if libdir != "bin" {

src/bootstrap/doc.rs

@@ -335,7 +335,7 @@ fn invoke_rustdoc(
     let footer = builder.src.join("src/doc/footer.inc");
     let version_info = out.join("version_info.html");
 
-    let mut cmd = builder.rustdoc_cmd(compiler.host);
+    let mut cmd = builder.rustdoc_cmd(compiler);
 
     let out = out.join("book");
 
@@ -415,7 +415,7 @@ impl Step for Standalone {
             }
 
             let html = out.join(filename).with_extension("html");
-            let rustdoc = builder.rustdoc(compiler.host);
+            let rustdoc = builder.rustdoc(compiler);
             if up_to_date(&path, &html) &&
                up_to_date(&footer, &html) &&
                up_to_date(&favicon, &html) &&
@@ -425,7 +425,7 @@ impl Step for Standalone {
                 continue
             }
 
-            let mut cmd = builder.rustdoc_cmd(compiler.host);
+            let mut cmd = builder.rustdoc_cmd(compiler);
             cmd.arg("--html-after-content").arg(&footer)
                .arg("--html-before-content").arg(&version_info)
                .arg("--html-in-header").arg(&favicon)
@@ -824,7 +824,7 @@ impl Step for Rustdoc {
         builder.ensure(Rustc { stage, target });
 
         // Build rustdoc.
-        builder.ensure(tool::Rustdoc { host: compiler.host });
+        builder.ensure(tool::Rustdoc { compiler: compiler });
 
         // Symlink compiler docs to the output directory of rustdoc documentation.
         let out_dir = builder.stage_out(compiler, Mode::ToolRustc)

src/bootstrap/test.rs

@@ -177,7 +177,7 @@ impl Step for Cargotest {
             cmd.arg(&builder.initial_cargo)
                 .arg(&out_dir)
                 .env("RUSTC", builder.rustc(compiler))
-                .env("RUSTDOC", builder.rustdoc(compiler.host)),
+                .env("RUSTDOC", builder.rustdoc(compiler)),
         );
     }
 }
@@ -560,7 +560,7 @@ impl Step for RustdocTheme {
                 builder.sysroot_libdir(self.compiler, self.compiler.host),
             )
             .env("CFG_RELEASE_CHANNEL", &builder.config.channel)
-            .env("RUSTDOC_REAL", builder.rustdoc(self.compiler.host))
+            .env("RUSTDOC_REAL", builder.rustdoc(self.compiler))
             .env("RUSTDOC_CRATE_VERSION", builder.rust_version())
             .env("RUSTC_BOOTSTRAP", "1");
         if let Some(linker) = builder.linker(self.compiler.host) {
@@ -995,7 +995,7 @@ impl Step for Compiletest {
             || (mode == "ui" && is_rustdoc_ui)
         {
             cmd.arg("--rustdoc-path")
-                .arg(builder.rustdoc(compiler.host));
+                .arg(builder.rustdoc(compiler));
         }
 
         cmd.arg("--src-base")
@@ -1451,7 +1451,7 @@ fn markdown_test(builder: &Builder<'_>, compiler: Compiler, markdown: &Path) ->
     }
 
     builder.info(&format!("doc tests for: {}", markdown.display()));
-    let mut cmd = builder.rustdoc_cmd(compiler.host);
+    let mut cmd = builder.rustdoc_cmd(compiler);
     builder.add_rust_test_threads(&mut cmd);
     cmd.arg("--test");
     cmd.arg(markdown);

src/bootstrap/tool.rs

@@ -430,7 +430,9 @@ impl Step for RemoteTestServer {
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct Rustdoc {
-    pub host: Interned<String>,
+    /// This should only ever be 0 or 2.
+    /// We sometimes want to reference the "bootstrap" rustdoc, which is why this option is here.
+    pub compiler: Compiler,
 }
 
 impl Step for Rustdoc {
@@ -444,12 +446,12 @@ impl Step for Rustdoc {
 
     fn make_run(run: RunConfig<'_>) {
         run.builder.ensure(Rustdoc {
-            host: run.host,
+            compiler: run.builder.compiler(run.builder.top_stage, run.host),
         });
     }
 
     fn run(self, builder: &Builder<'_>) -> PathBuf {
-        let target_compiler = builder.compiler(builder.top_stage, self.host);
+        let target_compiler = self.compiler;
         if target_compiler.stage == 0 {
             if !target_compiler.is_snapshot(builder) {
                 panic!("rustdoc in stage 0 must be snapshot rustdoc");