feat(core): add support for yarn@v4 link: syntax

Closes #293

Author: MarshallOfSound

package.json

@@ -30,6 +30,7 @@
     "Max Rohde (https://github.com/mxro)",
     "Michał Warać (https://github.com/auto200)",
     "Nick Saunders (https://github.com/nsaunders)",
+    "Samuel Attard (https://github.com/MarshallOfSound)",
     "Siraj (https://github.com/Syhner)",
     "Steve Beaugé (https://github.com/stevebeauge)",
     "Stuart Knightley (https://github.com/Stuk)",

site/src/content/docs/reference/specifier-types.mdx

@@ -39,6 +39,12 @@ A dependency that resolves to the latest available version. Includes wildcard pa
 
 Examples: `latest`, `*`
 
+### link
+
+A dependency that references a local package by path.
+
+Example: `link:../package-a`
+
 ### major
 
 A dependency specifier that only indicates the major version number.

src/specifier.rs

@@ -84,6 +84,7 @@ pub enum Specifier {
   Tag(Raw),
   Unsupported(Raw),
   Url(Raw),
+  Link(Raw),
   WorkspaceProtocol(WorkspaceProtocol),
 }
 
@@ -132,6 +133,9 @@ impl Specifier {
     if first_char == 'f' && value.starts_with("file:") {
       return Self::File(raw::Raw { raw: value.to_string() });
     }
+    if first_char == 'l' && value.starts_with("link:") {
+      return Self::Link(raw::Raw { raw: value.to_string() });
+    }
     if first_char == 'h' && (value.starts_with("http://") || value.starts_with("https://")) {
       return Self::Url(raw::Raw { raw: value.to_string() });
     }
@@ -324,6 +328,7 @@ impl Specifier {
       Self::ComplexSemver(s) => Self::ComplexSemver(s.with_range(range)),
       Self::File(s) => Self::File(s.with_range(range)),
       Self::Git(s) => Self::Git(s.with_range(range)),
+      Self::Link(s) => Self::Link(s.with_range(range)),
       Self::None => Self::None,
       Self::Tag(s) => Self::Tag(s.with_range(range)),
       Self::Unsupported(s) => Self::Unsupported(s.with_range(range)),
@@ -342,6 +347,7 @@ impl Specifier {
       Self::ComplexSemver(s) => Self::ComplexSemver(s.with_semver(semver)),
       Self::File(s) => Self::File(s.with_semver(semver)),
       Self::Git(s) => Self::Git(s.with_semver(semver)),
+      Self::Link(s) => Self::Link(s.with_semver(semver)),
       Self::None => Self::None,
       Self::Tag(s) => Self::Tag(s.with_semver(semver)),
       Self::Unsupported(s) => Self::Unsupported(s.with_semver(semver)),
@@ -357,6 +363,7 @@ impl Specifier {
       Self::ComplexSemver(inner) => inner.raw.clone(),
       Self::File(inner) => inner.raw.clone(),
       Self::Git(inner) => inner.raw.clone(),
+      Self::Link(inner) => inner.raw.clone(),
       Self::None => "".to_string(),
       Self::Tag(inner) => inner.raw.clone(),
       Self::Unsupported(inner) => inner.raw.clone(),
@@ -388,6 +395,7 @@ impl Specifier {
       Self::ComplexSemver(_) => "range-complex",
       Self::File(_) => "file",
       Self::Git(_) => "git",
+      Self::Link(_) => "link",
       Self::None => "missing",
       Self::Tag(_) => "tag",
       Self::Unsupported(_) => "unsupported",
@@ -427,6 +435,10 @@ impl Specifier {
     matches!(self, Self::WorkspaceProtocol(_))
   }
 
+  pub fn is_link(&self) -> bool {
+    matches!(self, Self::Link(_))
+  }
+
   /// Are both specifiers on eg. "-alpha", or neither have a release channel?
   pub fn has_same_release_channel_as(&self, other: &Specifier) -> bool {
     if let (Some(a), Some(b)) = (self.get_node_version(), other.get_node_version()) {

src/specifier/regexes.rs

@@ -63,6 +63,8 @@ lazy_static! {
   pub static ref ALIAS: Regex = Regex::new(r"^npm:.+").unwrap();
   /// "file:"
   pub static ref FILE: Regex = Regex::new(r"^file:").unwrap();
+  /// "link:"
+  pub static ref LINK: Regex = Regex::new(r"^link:").unwrap();
   /// "workspace:"
   pub static ref WORKSPACE_PROTOCOL: Regex = Regex::new(r"^workspace:").unwrap();
   /// "https://"

src/specifier_test.rs

@@ -372,6 +372,19 @@ fn file_paths() {
   }
 }
 
+#[test]
+fn links() {
+  let cases: Vec<&str> = vec!["link:../foo", "link:path/to/foo"];
+  for value in cases {
+    match Specifier::new(value, None) {
+      Specifier::Link(actual) => {
+        assert_eq!(actual.raw, value)
+      }
+      _ => panic!("Expected Link"),
+    }
+  }
+}
+
 #[test]
 fn urls() {
   let cases: Vec<&str> = vec![

src/visit_packages/preferred_semver.rs

@@ -44,6 +44,12 @@ pub fn visit(dependency: &Dependency, ctx: &Context) {
         return;
       }
       debug!("{L4}it depends on the local instance");
+      if instance.descriptor.specifier.is_link() {
+        debug!("{L5}it is using the link specifier");
+        debug!("{L6}mark as satisfying local");
+        instance.mark_valid(ValidInstance::SatisfiesLocal, &instance.descriptor.specifier);
+        return;
+      }
       if instance.descriptor.specifier.is_workspace_protocol() {
         debug!("{L5}it is using the workspace protocol");
         if !ctx.config.rcfile.strict {

src/visit_packages/preferred_semver_test.rs

@@ -466,6 +466,51 @@ mod local {
       },
     ]);
   }
+
+  #[test]
+  fn instance_is_linked() {
+    let ctx = TestBuilder::new()
+      .with_packages(vec![
+        json!({
+          "name": "package-a",
+          "version": "1.0.0"
+        }),
+        json!({
+          "name": "package-b",
+          "version": "2.0.0",
+          "dependencies": {
+            "package-a": "link:../package-a"
+          }
+        }),
+      ])
+      .build_and_visit_packages();
+    expect(&ctx).to_have_instances(vec![
+      ExpectedInstance {
+        state: InstanceState::valid(IsLocalAndValid),
+        dependency_name: "package-b",
+        id: "package-b in /version of package-b",
+        actual: "2.0.0",
+        expected: Some("2.0.0"),
+        overridden: None,
+      },
+      ExpectedInstance {
+        state: InstanceState::valid(IsLocalAndValid),
+        dependency_name: "package-a",
+        id: "package-a in /version of package-a",
+        actual: "1.0.0",
+        expected: Some("1.0.0"),
+        overridden: None,
+      },
+      ExpectedInstance {
+        state: InstanceState::valid(IsLocalAndValid),
+        dependency_name: "package-a",
+        id: "package-a in /dependencies of package-b",
+        actual: "link:../package-a",
+        expected: Some("link:../package-a"),
+        overridden: None,
+      },
+    ]);
+  }
 }
 
 mod highest_or_lowest {