Auto merge of #13993 - epage:path-source, r=ehuss

refactor(source): Split `RecursivePathSource` out of `PathSource`

### What does this PR try to resolve?

`PathSource` serves a couple of roles
- When a dependency / patch uses `path` (non-recursive)
- As the implementation details of a `git` source (recursive)
- Dependency overrides (recursive)

Instead of using a `PathSource::new` vs `PathSouce::new_recursive`, this does `RecursivePathSource::new`.  This makes the intent a lot clearer and makes it easier to customize the behavior to each role that is played.

Specifically, there are two ways I expect to leverage this refactor
- Improve the interplay between `RecursivePathSource` and `read_packages` to reduce the duplicate package warnings for git sources (#13992)
- cargo script will change the semantics of path sources slightly and I'm assuming having a distinct source will make this easier

### How should we test and review this PR?

### Additional information

Author: bors

src/cargo/core/workspace.rs

@@ -1142,8 +1142,7 @@ impl<'gctx> Workspace<'gctx> {
                 MaybePackage::Package(ref p) => p.clone(),
                 MaybePackage::Virtual(_) => continue,
             };
-            let mut src = PathSource::new(pkg.root(), pkg.package_id().source_id(), self.gctx);
-            src.preload_with(pkg);
+            let src = PathSource::preload_with(pkg, self.gctx);
             registry.add_preloaded(Box::new(src));
         }
     }

src/cargo/ops/resolve.rs

@@ -73,7 +73,7 @@ use crate::core::PackageSet;
 use crate::core::SourceId;
 use crate::core::Workspace;
 use crate::ops;
-use crate::sources::PathSource;
+use crate::sources::RecursivePathSource;
 use crate::util::cache_lock::CacheLockMode;
 use crate::util::errors::CargoResult;
 use crate::util::CanonicalUrl;
@@ -453,7 +453,7 @@ pub fn add_overrides<'a>(
 
     for (path, definition) in paths {
         let id = SourceId::for_path(&path)?;
-        let mut source = PathSource::new_recursive(&path, id, ws.gctx());
+        let mut source = RecursivePathSource::new(&path, id, ws.gctx());
         source.update().with_context(|| {
             format!(
                 "failed to update path override `{}` \

src/cargo/sources/git/source.rs

@@ -10,7 +10,7 @@ use crate::sources::source::MaybePackage;
 use crate::sources::source::QueryKind;
 use crate::sources::source::Source;
 use crate::sources::IndexSummary;
-use crate::sources::PathSource;
+use crate::sources::RecursivePathSource;
 use crate::util::cache_lock::CacheLockMode;
 use crate::util::errors::CargoResult;
 use crate::util::hex::short_hash;
@@ -24,7 +24,7 @@ use tracing::trace;
 use url::Url;
 
 /// `GitSource` contains one or more packages gathering from a Git repository.
-/// Under the hood it uses [`PathSource`] to discover packages inside the
+/// Under the hood it uses [`RecursivePathSource`] to discover packages inside the
 /// repository.
 ///
 /// ## Filesystem layout
@@ -79,7 +79,7 @@ pub struct GitSource<'gctx> {
     ///
     /// This gets set to `Some` after the git repo has been checked out
     /// (automatically handled via [`GitSource::block_until_ready`]).
-    path_source: Option<PathSource<'gctx>>,
+    path_source: Option<RecursivePathSource<'gctx>>,
     /// A short string that uniquely identifies the version of the checkout.
     ///
     /// This is typically a 7-character string of the OID hash, automatically
@@ -356,7 +356,7 @@ impl<'gctx> Source for GitSource<'gctx> {
         let source_id = self
             .source_id
             .with_git_precise(Some(actual_rev.to_string()));
-        let path_source = PathSource::new_recursive(&checkout_path, source_id, self.gctx);
+        let path_source = RecursivePathSource::new(&checkout_path, source_id, self.gctx);
 
         self.path_source = Some(path_source);
         self.short_id = Some(short_id.as_str().into());

src/cargo/sources/mod.rs

@@ -30,6 +30,7 @@ pub use self::config::SourceConfigMap;
 pub use self::directory::DirectorySource;
 pub use self::git::GitSource;
 pub use self::path::PathSource;
+pub use self::path::RecursivePathSource;
 pub use self::registry::{
     IndexSummary, RegistrySource, CRATES_IO_DOMAIN, CRATES_IO_INDEX, CRATES_IO_REGISTRY,
 };