Keep list of submodules close to list of vendored workspaces

This moves the list of submodules needed to vendor close to the list of
cargo workspaces with the intent to help ensure they keep up-to-date and
in sync.

Author: ehuss

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

@@ -1026,7 +1026,7 @@ impl Step for PlainSourceTarball {
             let mut cmd = command(&builder.initial_cargo);
             cmd.arg("vendor").arg("--versioned-dirs");
 
-            for p in default_paths_to_vendor(builder) {
+            for (p, _) in default_paths_to_vendor(builder) {
                 cmd.arg("--sync").arg(p);
             }
 

src/bootstrap/src/core/build_steps/vendor.rs

@@ -4,24 +4,26 @@ use crate::core::build_steps::tool::SUBMODULES_FOR_RUSTBOOK;
 use crate::core::builder::{Builder, RunConfig, ShouldRun, Step};
 use crate::utils::exec::command;
 
-/// List of default paths used for vendoring for `x vendor` and dist tarballs.
-pub fn default_paths_to_vendor(builder: &Builder<'_>) -> Vec<PathBuf> {
-    let mut paths = vec![];
-    for p in [
-        "src/tools/cargo/Cargo.toml",
-        "src/tools/rust-analyzer/Cargo.toml",
-        "compiler/rustc_codegen_cranelift/Cargo.toml",
-        "compiler/rustc_codegen_gcc/Cargo.toml",
-        "library/Cargo.toml",
-        "src/bootstrap/Cargo.toml",
-        "src/tools/rustbook/Cargo.toml",
-        "src/tools/rustc-perf/Cargo.toml",
-        "src/tools/opt-dist/Cargo.toml",
-    ] {
-        paths.push(builder.src.join(p));
-    }
-
-    paths
+/// Returns the cargo workspaces to vendor for `x vendor` and dist tarballs.
+///
+/// Returns a `Vec` of `(path_to_manifest, submodules_required)` where
+/// `path_to_manifest` is the cargo workspace, and `submodules_required` is
+/// the set of submodules that must be available.
+pub fn default_paths_to_vendor(builder: &Builder<'_>) -> Vec<(PathBuf, Vec<&'static str>)> {
+    [
+        ("src/tools/cargo/Cargo.toml", vec!["src/tools/cargo"]),
+        ("src/tools/rust-analyzer/Cargo.toml", vec![]),
+        ("compiler/rustc_codegen_cranelift/Cargo.toml", vec![]),
+        ("compiler/rustc_codegen_gcc/Cargo.toml", vec![]),
+        ("library/Cargo.toml", vec![]),
+        ("src/bootstrap/Cargo.toml", vec![]),
+        ("src/tools/rustbook/Cargo.toml", SUBMODULES_FOR_RUSTBOOK.into()),
+        ("src/tools/rustc-perf/Cargo.toml", vec!["src/tools/rustc-perf"]),
+        ("src/tools/opt-dist/Cargo.toml", vec![]),
+    ]
+    .into_iter()
+    .map(|(path, submodules)| (builder.src.join(path), submodules))
+    .collect()
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
@@ -56,15 +58,16 @@ impl Step for Vendor {
             cmd.arg("--versioned-dirs");
         }
 
+        let to_vendor = default_paths_to_vendor(builder);
         // These submodules must be present for `x vendor` to work.
-        for submodule in
-            SUBMODULES_FOR_RUSTBOOK.iter().chain(["src/tools/cargo", "src/tools/rustc-perf"].iter())
-        {
-            builder.build.require_submodule(submodule, None);
+        for (_, submodules) in &to_vendor {
+            for submodule in submodules {
+                builder.build.require_submodule(submodule, None);
+            }
         }
 
         // Sync these paths by default.
-        for p in default_paths_to_vendor(builder) {
+        for (p, _) in &to_vendor {
             cmd.arg("--sync").arg(p);
         }