Add manifest docs fallback.

.github/workflows/ci.yml

@@ -320,7 +320,7 @@ jobs:
           - name: dist-aarch64-apple
             env:
               SCRIPT: "./x.py dist --stage 2"
-              RUST_CONFIGURE_ARGS: "--build=x86_64-apple-darwin --host=aarch64-apple-darwin --target=aarch64-apple-darwin --enable-full-tools --enable-sanitizers --enable-profiler --set rust.jemalloc --set llvm.ninja=false"
+              RUST_CONFIGURE_ARGS: "--build=x86_64-apple-darwin --host=aarch64-apple-darwin --target=aarch64-apple-darwin --enable-full-tools --enable-sanitizers --enable-profiler --disable-docs --set rust.jemalloc --set llvm.ninja=false"
               RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
               USE_XCODE_CLANG: 1
               MACOSX_DEPLOYMENT_TARGET: 11.0

src/bootstrap/dist.rs

@@ -1483,11 +1483,10 @@ impl Step for Extended {
             };
             prepare("rustc");
             prepare("cargo");
-            prepare("rust-docs");
             prepare("rust-std");
             prepare("rust-analysis");
             prepare("clippy");
-            for tool in &["rust-demangler", "rls", "rust-analyzer", "miri"] {
+            for tool in &["rust-docs", "rust-demangler", "rls", "rust-analyzer", "miri"] {
                 if built_tools.contains(tool) {
                     prepare(tool);
                 }

src/ci/github-actions/ci.yml

@@ -496,6 +496,7 @@ jobs:
                 --enable-full-tools
                 --enable-sanitizers
                 --enable-profiler
+                --disable-docs
                 --set rust.jemalloc
                 --set llvm.ninja=false
               RUSTC_RETRY_LINKER_ON_SEGFAULT: 1

src/tools/build-manifest/README.md

@@ -20,8 +20,7 @@ Then, you can generate the manifest and all the packages from `path/to/dist` to
 `path/to/output` with:
 
 ```
-$ cargo +nightly run path/to/dist path/to/output 1970-01-01 http://example.com \
-    CHANNEL VERSION
+$ cargo +nightly run path/to/dist path/to/output 1970-01-01 http://example.com CHANNEL
 ```
 
 Remember to replace `CHANNEL` with the channel you produced dist artifacts of

src/tools/build-manifest/src/main.rs

@@ -155,17 +155,19 @@ static TARGETS: &[&str] = &[
     "x86_64-unknown-hermit",
 ];
 
-static DOCS_TARGETS: &[&str] = &[
-    "aarch64-unknown-linux-gnu",
-    "i686-apple-darwin",
-    "i686-pc-windows-gnu",
-    "i686-pc-windows-msvc",
-    "i686-unknown-linux-gnu",
-    "x86_64-apple-darwin",
-    "x86_64-pc-windows-gnu",
-    "x86_64-pc-windows-msvc",
-    "x86_64-unknown-linux-gnu",
-    "x86_64-unknown-linux-musl",
+/// This allows the manifest to contain rust-docs for hosts that don't build
+/// docs.
+///
+/// Tuples of `(host_partial, host_instead)`. If the host does not have the
+/// rust-docs component available, then if the host name contains
+/// `host_partial`, it will use the docs from `host_instead` instead.
+///
+/// The order here matters, more specific entries should be first.
+static DOCS_FALLBACK: &[(&str, &str)] = &[
+    ("-apple-", "x86_64-apple-darwin"),
+    ("aarch64", "aarch64-unknown-linux-gnu"),
+    ("arm-", "aarch64-unknown-linux-gnu"),
+    ("", "x86_64-unknown-linux-gnu"),
 ];
 
 static MSI_INSTALLERS: &[&str] = &[
@@ -301,23 +303,27 @@ impl Builder {
     }
 
     fn add_packages_to(&mut self, manifest: &mut Manifest) {
-        let mut package = |name, targets| self.package(name, &mut manifest.pkg, targets);
-        package("rustc", HOSTS);
-        package("rustc-dev", HOSTS);
-        package("reproducible-artifacts", HOSTS);
-        package("rustc-docs", HOSTS);
-        package("cargo", HOSTS);
-        package("rust-mingw", MINGW);
-        package("rust-std", TARGETS);
-        package("rust-docs", DOCS_TARGETS);
-        package("rust-src", &["*"]);
-        package("rls-preview", HOSTS);
-        package("rust-analyzer-preview", HOSTS);
-        package("clippy-preview", HOSTS);
-        package("miri-preview", HOSTS);
-        package("rustfmt-preview", HOSTS);
-        package("rust-analysis", TARGETS);
-        package("llvm-tools-preview", TARGETS);
+        macro_rules! package {
+            ($name:expr, $targets:expr) => {
+                self.package($name, &mut manifest.pkg, $targets, &[])
+            };
+        }
+        package!("rustc", HOSTS);
+        package!("rustc-dev", HOSTS);
+        package!("reproducible-artifacts", HOSTS);
+        package!("rustc-docs", HOSTS);
+        package!("cargo", HOSTS);
+        package!("rust-mingw", MINGW);
+        package!("rust-std", TARGETS);
+        self.package("rust-docs", &mut manifest.pkg, HOSTS, DOCS_FALLBACK);
+        package!("rust-src", &["*"]);
+        package!("rls-preview", HOSTS);
+        package!("rust-analyzer-preview", HOSTS);
+        package!("clippy-preview", HOSTS);
+        package!("miri-preview", HOSTS);
+        package!("rustfmt-preview", HOSTS);
+        package!("rust-analysis", TARGETS);
+        package!("llvm-tools-preview", TARGETS);
     }
 
     fn add_artifacts_to(&mut self, manifest: &mut Manifest) {
@@ -500,7 +506,13 @@ impl Builder {
             .extend(pkgs.iter().map(|s| (*s).to_owned()));
     }
 
-    fn package(&mut self, pkgname: &str, dst: &mut BTreeMap<String, Package>, targets: &[&str]) {
+    fn package(
+        &mut self,
+        pkgname: &str,
+        dst: &mut BTreeMap<String, Package>,
+        targets: &[&str],
+        fallback: &[(&str, &str)],
+    ) {
         let version_info = self
             .versions
             .version(&PkgType::from_component(pkgname))
@@ -512,16 +524,32 @@ impl Builder {
             is_present = false; // Pretend the component is entirely missing.
         }
 
+        macro_rules! tarball_name {
+            ($target_name:expr) => {
+                self.versions.tarball_name(&PkgType::from_component(pkgname), $target_name).unwrap()
+            };
+        }
+        let mut target_from_compressed_tar = |target_name| {
+            let target = Target::from_compressed_tar(self, &tarball_name!(target_name));
+            if target.available {
+                return target;
+            }
+            for (substr, fallback_target) in fallback {
+                if target_name.contains(substr) {
+                    let t = Target::from_compressed_tar(self, &tarball_name!(fallback_target));
+                    // Fallbacks must always be available.
+                    assert!(t.available);
+                    return t;
+                }
+            }
+            Target::unavailable()
+        };
+
         let targets = targets
             .iter()
             .map(|name| {
                 let target = if is_present {
-                    let filename = self
-                        .versions
-                        .tarball_name(&PkgType::from_component(pkgname), name)
-                        .unwrap();
-
-                    Target::from_compressed_tar(self, &filename)
+                    target_from_compressed_tar(name)
                 } else {
                     // If the component is not present for this build add it anyway but mark it as
                     // unavailable -- this way rustup won't allow upgrades without --force

src/tools/build-manifest/src/versions.rs

@@ -169,7 +169,7 @@ impl Versions {
     }
 
     pub(crate) fn archive_name(
-        &mut self,
+        &self,
         package: &PkgType,
         target: &str,
         extension: &str,
@@ -189,11 +189,7 @@ impl Versions {
         }
     }
 
-    pub(crate) fn tarball_name(
-        &mut self,
-        package: &PkgType,
-        target: &str,
-    ) -> Result<String, Error> {
+    pub(crate) fn tarball_name(&self, package: &PkgType, target: &str) -> Result<String, Error> {
         self.archive_name(package, target, "tar.gz")
     }