refactor(toml): Only collect nested paths when needed

This simplifies the interface for `toml/mod.rs` and reduces the work we
do.

src/cargo/core/workspace.rs

@@ -420,7 +420,6 @@ impl<'gctx> Workspace<'gctx> {
         let source = SourceId::for_path(self.root())?;
 
         let mut warnings = Vec::new();
-        let mut nested_paths = Vec::new();
 
         let mut patch = HashMap::new();
         for (url, deps) in config_patch.into_iter().flatten() {
@@ -442,7 +441,6 @@ impl<'gctx> Workspace<'gctx> {
                             dep,
                             name,
                             source,
-                            &mut nested_paths,
                             self.gctx,
                             &mut warnings,
                             /* platform */ None,
@@ -1063,7 +1061,7 @@ impl<'gctx> Workspace<'gctx> {
             return Ok(p);
         }
         let source_id = SourceId::for_path(manifest_path.parent().unwrap())?;
-        let (package, _nested_paths) = ops::read_package(manifest_path, source_id, self.gctx)?;
+        let package = ops::read_package(manifest_path, source_id, self.gctx)?;
         loaded.insert(manifest_path.to_path_buf(), package.clone());
         Ok(package)
     }
@@ -1596,7 +1594,7 @@ impl<'gctx> Packages<'gctx> {
             Entry::Occupied(e) => Ok(e.into_mut()),
             Entry::Vacant(v) => {
                 let source_id = SourceId::for_path(key)?;
-                let (manifest, _nested_paths) = read_manifest(manifest_path, source_id, self.gctx)?;
+                let manifest = read_manifest(manifest_path, source_id, self.gctx)?;
                 Ok(v.insert(match manifest {
                     EitherManifest::Real(manifest) => {
                         MaybePackage::Package(Package::new(manifest, manifest_path))
@@ -1746,7 +1744,7 @@ pub fn find_workspace_root(
     find_workspace_root_with_loader(manifest_path, gctx, |self_path| {
         let key = self_path.parent().unwrap();
         let source_id = SourceId::for_path(key)?;
-        let (manifest, _nested_paths) = read_manifest(self_path, source_id, gctx)?;
+        let manifest = read_manifest(self_path, source_id, gctx)?;
         Ok(manifest
             .workspace_config()
             .get_ws_root(self_path, manifest_path))

src/cargo/ops/cargo_package.rs

@@ -456,8 +456,7 @@ fn build_lock(ws: &Workspace<'_>, orig_pkg: &Package) -> CargoResult<String> {
     let toml_manifest =
         prepare_for_publish(orig_pkg.manifest().resolved_toml(), ws, orig_pkg.root())?;
     let source_id = orig_pkg.package_id().source_id();
-    let (manifest, _nested_paths) =
-        to_real_manifest(toml_manifest, source_id, orig_pkg.manifest_path(), gctx)?;
+    let manifest = to_real_manifest(toml_manifest, source_id, orig_pkg.manifest_path(), gctx)?;
     let new_pkg = Package::new(manifest, orig_pkg.manifest_path());
 
     // Regenerate Cargo.lock using the old one as a guide.

src/cargo/ops/cargo_read_manifest.rs

@@ -3,7 +3,7 @@ use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
 
-use crate::core::{EitherManifest, Package, PackageId, SourceId};
+use crate::core::{EitherManifest, Manifest, Package, PackageId, SourceId};
 use crate::util::errors::CargoResult;
 use crate::util::important_paths::find_project_manifest_exact;
 use crate::util::toml::read_manifest;
@@ -15,13 +15,13 @@ pub fn read_package(
     path: &Path,
     source_id: SourceId,
     gctx: &GlobalContext,
-) -> CargoResult<(Package, Vec<PathBuf>)> {
+) -> CargoResult<Package> {
     trace!(
         "read_package; path={}; source-id={}",
         path.display(),
         source_id
     );
-    let (manifest, nested) = read_manifest(path, source_id, gctx)?;
+    let manifest = read_manifest(path, source_id, gctx)?;
     let manifest = match manifest {
         EitherManifest::Real(manifest) => manifest,
         EitherManifest::Virtual(..) => anyhow::bail!(
@@ -31,7 +31,7 @@ pub fn read_package(
         ),
     };
 
-    Ok((Package::new(manifest, path), nested))
+    Ok(Package::new(manifest, path))
 }
 
 pub fn read_packages(
@@ -107,6 +107,44 @@ pub fn read_packages(
     }
 }
 
+fn nested_paths(manifest: &Manifest) -> Vec<PathBuf> {
+    let mut nested_paths = Vec::new();
+    let resolved = manifest.resolved_toml();
+    let dependencies = resolved
+        .dependencies
+        .iter()
+        .chain(resolved.build_dependencies())
+        .chain(resolved.dev_dependencies())
+        .chain(
+            resolved
+                .target
+                .as_ref()
+                .into_iter()
+                .flat_map(|t| t.values())
+                .flat_map(|t| {
+                    t.dependencies
+                        .iter()
+                        .chain(t.build_dependencies())
+                        .chain(t.dev_dependencies())
+                }),
+        );
+    for dep_table in dependencies {
+        for dep in dep_table.values() {
+            let cargo_util_schemas::manifest::InheritableDependency::Value(dep) = dep else {
+                continue;
+            };
+            let cargo_util_schemas::manifest::TomlDependency::Detailed(dep) = dep else {
+                continue;
+            };
+            let Some(path) = dep.path.as_ref() else {
+                continue;
+            };
+            nested_paths.push(PathBuf::from(path.as_str()));
+        }
+    }
+    nested_paths
+}
+
 fn walk(path: &Path, callback: &mut dyn FnMut(&Path) -> CargoResult<bool>) -> CargoResult<()> {
     if !callback(path)? {
         trace!("not processing {}", path.display());
@@ -151,7 +189,7 @@ fn read_nested_packages(
 
     let manifest_path = find_project_manifest_exact(path, "Cargo.toml")?;
 
-    let (manifest, nested) = match read_manifest(&manifest_path, source_id, gctx) {
+    let manifest = match read_manifest(&manifest_path, source_id, gctx) {
         Err(err) => {
             // Ignore malformed manifests found on git repositories
             //
@@ -174,6 +212,7 @@ fn read_nested_packages(
         EitherManifest::Real(manifest) => manifest,
         EitherManifest::Virtual(..) => return Ok(()),
     };
+    let nested = nested_paths(&manifest);
     let pkg = Package::new(manifest, &manifest_path);
 
     let pkg_id = pkg.package_id();

src/cargo/sources/path.rs

@@ -110,7 +110,7 @@ impl<'gctx> PathSource<'gctx> {
             ops::read_packages(&self.path, self.source_id, self.gctx)
         } else {
             let path = self.path.join("Cargo.toml");
-            let (pkg, _) = ops::read_package(&path, self.source_id, self.gctx)?;
+            let pkg = ops::read_package(&path, self.source_id, self.gctx)?;
             Ok(vec![pkg])
         }
     }

src/cargo/util/toml/mod.rs

@@ -47,7 +47,7 @@ pub fn read_manifest(
     path: &Path,
     source_id: SourceId,
     gctx: &GlobalContext,
-) -> CargoResult<(EitherManifest, Vec<PathBuf>)> {
+) -> CargoResult<EitherManifest> {
     let contents =
         read_toml_string(path, gctx).map_err(|err| ManifestError::new(err, path.into()))?;
     let document =
@@ -174,13 +174,13 @@ fn convert_toml(
     manifest_file: &Path,
     source_id: SourceId,
     gctx: &GlobalContext,
-) -> CargoResult<(EitherManifest, Vec<PathBuf>)> {
+) -> CargoResult<EitherManifest> {
     return if manifest.package().is_some() {
-        let (manifest, paths) = to_real_manifest(manifest, source_id, manifest_file, gctx)?;
-        Ok((EitherManifest::Real(manifest), paths))
+        let manifest = to_real_manifest(manifest, source_id, manifest_file, gctx)?;
+        Ok(EitherManifest::Real(manifest))
     } else {
-        let (m, paths) = to_virtual_manifest(manifest, source_id, manifest_file, gctx)?;
-        Ok((EitherManifest::Virtual(m), paths))
+        let manifest = to_virtual_manifest(manifest, source_id, manifest_file, gctx)?;
+        Ok(EitherManifest::Virtual(manifest))
     };
 }
 
@@ -464,7 +464,7 @@ pub fn to_real_manifest(
     source_id: SourceId,
     manifest_file: &Path,
     gctx: &GlobalContext,
-) -> CargoResult<(Manifest, Vec<PathBuf>)> {
+) -> CargoResult<Manifest> {
     fn get_ws(
         gctx: &GlobalContext,
         resolved_path: &Path,
@@ -516,7 +516,6 @@ pub fn to_real_manifest(
         }
     }
 
-    let mut nested_paths = vec![];
     let mut warnings = vec![];
     let mut errors = vec![];
 
@@ -770,7 +769,6 @@ pub fn to_real_manifest(
     let mut manifest_ctx = ManifestContext {
         deps: &mut deps,
         source_id,
-        nested_paths: &mut nested_paths,
         gctx,
         warnings: &mut warnings,
         features: &features,
@@ -1272,15 +1270,15 @@ pub fn to_real_manifest(
 
     manifest.feature_gate()?;
 
-    Ok((manifest, nested_paths))
+    Ok(manifest)
 }
 
 fn to_virtual_manifest(
     me: manifest::TomlManifest,
     source_id: SourceId,
     manifest_file: &Path,
     gctx: &GlobalContext,
-) -> CargoResult<(VirtualManifest, Vec<PathBuf>)> {
+) -> CargoResult<VirtualManifest> {
     let root = manifest_file.parent().unwrap();
 
     if let Some(deps) = me
@@ -1302,7 +1300,6 @@ fn to_virtual_manifest(
         bail!("this virtual manifest specifies a `{field}` section, which is not allowed");
     }
 
-    let mut nested_paths = Vec::new();
     let mut warnings = Vec::new();
     let mut deps = Vec::new();
     let empty = Vec::new();
@@ -1315,7 +1312,6 @@ fn to_virtual_manifest(
         let mut manifest_ctx = ManifestContext {
             deps: &mut deps,
             source_id,
-            nested_paths: &mut nested_paths,
             gctx,
             warnings: &mut warnings,
             platform: None,
@@ -1376,7 +1372,7 @@ fn to_virtual_manifest(
         manifest.warnings_mut().add_warning(warning);
     }
 
-    Ok((manifest, nested_paths))
+    Ok(manifest)
 }
 
 fn replace(
@@ -1467,7 +1463,6 @@ fn patch(
 struct ManifestContext<'a, 'b> {
     deps: &'a mut Vec<Dependency>,
     source_id: SourceId,
-    nested_paths: &'a mut Vec<PathBuf>,
     gctx: &'b GlobalContext,
     warnings: &'a mut Vec<String>,
     platform: Option<Platform>,
@@ -1563,7 +1558,7 @@ fn inheritable_from_path(
     };
 
     let source_id = SourceId::for_path(workspace_path_root)?;
-    let (man, _) = read_manifest(&workspace_path, source_id, gctx)?;
+    let man = read_manifest(&workspace_path, source_id, gctx)?;
     match man.workspace_config() {
         WorkspaceConfig::Root(root) => {
             gctx.ws_roots
@@ -1885,7 +1880,6 @@ pub(crate) fn to_dependency<P: ResolveToPath + Clone>(
     dep: &manifest::TomlDependency<P>,
     name: &str,
     source_id: SourceId,
-    nested_paths: &mut Vec<PathBuf>,
     gctx: &GlobalContext,
     warnings: &mut Vec<String>,
     platform: Option<Platform>,
@@ -1899,7 +1893,6 @@ pub(crate) fn to_dependency<P: ResolveToPath + Clone>(
         &mut ManifestContext {
             deps: &mut Vec::new(),
             source_id,
-            nested_paths,
             gctx,
             warnings,
             platform,
@@ -2068,7 +2061,6 @@ fn detailed_dep_to_dependency<P: ResolveToPath + Clone>(
         }
         (None, Some(path), _, _) => {
             let path = path.resolve(manifest_ctx.gctx);
-            manifest_ctx.nested_paths.push(path.clone());
             // If the source ID for the package we're parsing is a path
             // source, then we normalize the path here to get rid of
             // components like `..`.