Clean up legacy workspace root concept (#17864)

Prompted by https://github.com/astral-sh/uv/issues/17855 — I think this
branch is just dead code?

crates/uv-resolver/src/lock/export/mod.rs

@@ -158,7 +158,7 @@ impl<'lock> ExportableRequirements<'lock> {
         }
 
         // Add requirements that are exclusive to the workspace root (e.g., dependency groups in
-        // (legacy) non-project workspace roots).
+        // non-project workspace roots).
         let root_requirements = target
             .lock()
             .requirements()

crates/uv-resolver/src/lock/installable.rs

@@ -249,7 +249,7 @@ pub trait Installable<'lock> {
         }
 
         // Add any dependency groups that are exclusive to the workspace root (e.g., dev
-        // dependencies in (legacy) non-project workspace roots).
+        // dependencies in non-project workspace roots).
         for (group, dependency) in self
             .lock()
             .dependency_groups()

crates/uv-workspace/src/workspace.rs

@@ -97,14 +97,10 @@ pub enum MemberDiscovery {
 /// Whether a "project" must be defined via a `[project]` table.
 #[derive(Debug, Default, Clone, Hash, PartialEq, Eq)]
 pub enum ProjectDiscovery {
-    /// The `[project]` table is optional; when missing, the target is treated as virtual.
+    /// The `[project]` table is optional; when missing, the target is treated as a virtual
+    /// project with only dependency groups.
     #[default]
     Optional,
-    /// A `[project]` table must be defined, unless `[tool.uv.workspace]` is present indicating a
-    /// legacy non-project workspace root.
-    ///
-    /// If neither is defined, discovery will fail.
-    Legacy,
     /// A `[project]` table must be defined.
     ///
     /// If not defined, discovery will fail.
@@ -114,20 +110,12 @@ pub enum ProjectDiscovery {
 impl ProjectDiscovery {
     /// Whether a `[project]` table is required.
     pub fn allows_implicit_workspace(&self) -> bool {
-        match self {
-            Self::Optional => true,
-            Self::Legacy => false,
-            Self::Required => false,
-        }
+        matches!(self, Self::Optional)
     }
 
-    /// Whether a legacy workspace root is allowed.
-    pub fn allows_legacy_workspace(&self) -> bool {
-        match self {
-            Self::Optional => true,
-            Self::Legacy => true,
-            Self::Required => false,
-        }
+    /// Whether a non-project workspace root is allowed.
+    pub fn allows_non_project_workspace(&self) -> bool {
+        matches!(self, Self::Optional)
     }
 }
 
@@ -184,7 +172,7 @@ impl Workspace {
     ///   * If an explicit workspace root exists: Collect workspace from this root, we're done.
     ///   * If there is no explicit workspace: We have a single project workspace, we're done.
     ///
-    /// Note that there are two kinds of workspace roots: projects, and (legacy) non-project roots.
+    /// Note that there are two kinds of workspace roots: projects, and non-project roots.
     /// The non-project roots lack a `[project]` table, and so are not themselves projects, as in:
     /// ```toml
     /// [tool.uv.workspace]
@@ -270,7 +258,7 @@ impl Workspace {
             workspace_root.simplified_display()
         );
 
-        // Unlike in `ProjectWorkspace` discovery, we might be in a legacy non-project root without
+        // Unlike in `ProjectWorkspace` discovery, we might be in a non-project root without
         // being in any specific project.
         let current_project = pyproject_toml
             .project
@@ -365,7 +353,7 @@ impl Workspace {
         }
     }
 
-    /// Returns `true` if the workspace has a (legacy) non-project root.
+    /// Returns `true` if the workspace has a non-project root.
     pub fn is_non_project(&self) -> bool {
         !self
             .packages
@@ -1745,7 +1733,7 @@ impl VirtualProject {
             .as_ref()
             .and_then(|tool| tool.uv.as_ref())
             .and_then(|uv| uv.workspace.as_ref())
-            .filter(|_| options.project.allows_legacy_workspace())
+            .filter(|_| options.project.allows_non_project_workspace())
         {
             // Otherwise, if it contains a `tool.uv.workspace` table, it's a non-project workspace
             // root.

crates/uv/src/commands/project/install_target.rs

@@ -37,7 +37,7 @@ pub(crate) enum InstallTarget<'lock> {
         workspace: &'lock Workspace,
         lock: &'lock Lock,
     },
-    /// An entire workspace with a (legacy) non-project root.
+    /// An entire workspace with a non-project root.
     NonProjectWorkspace {
         workspace: &'lock Workspace,
         lock: &'lock Lock,

crates/uv/tests/it/edit.rs

@@ -4928,7 +4928,7 @@ fn add_lower_bound_local() -> Result<()> {
     Ok(())
 }
 
-/// Add dependencies to a (legacy) non-project workspace root.
+/// Add dependencies to a non-project workspace root.
 #[test]
 fn add_non_project() -> Result<()> {
     let context = uv_test::test_context!("3.12");

crates/uv/tests/it/lock.rs

@@ -17191,10 +17191,10 @@ fn lock_constrained_environment() -> Result<()> {
     Ok(())
 }
 
-/// Lock with a user-provided constraint on the space of supported environments, using a legacy
-/// virtual workspace root.
+/// Lock with a user-provided constraint on the space of supported environments, using a
+/// non-project workspace root.
 #[test]
-fn lock_constrained_environment_legacy() -> Result<()> {
+fn lock_constrained_environment_non_project() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
@@ -17389,7 +17389,7 @@ fn lock_overlapping_environment() -> Result<()> {
     Ok(())
 }
 
-/// Lock a (legacy) non-project workspace root with forked dev dependencies.
+/// Lock a non-project workspace root with forked dev dependencies.
 #[test]
 fn lock_non_project_fork() -> Result<()> {
     let context = uv_test::test_context!("3.10");
@@ -17585,7 +17585,7 @@ fn lock_non_project_fork() -> Result<()> {
     Ok(())
 }
 
-/// Lock a (legacy) non-project workspace root with a conditional dependency.
+/// Lock a non-project workspace root with a conditional dependency.
 #[test]
 fn lock_non_project_conditional() -> Result<()> {
     let context = uv_test::test_context!("3.12");
@@ -17690,7 +17690,7 @@ fn lock_non_project_conditional() -> Result<()> {
     Ok(())
 }
 
-/// Lock a (legacy) non-project workspace root with `dependency-groups`.
+/// Lock a non-project workspace root with `dependency-groups`.
 #[test]
 fn lock_non_project_group() -> Result<()> {
     let context = uv_test::test_context!("3.10");
@@ -17832,7 +17832,7 @@ fn lock_non_project_group() -> Result<()> {
     Ok(())
 }
 
-/// Lock a (legacy) non-project workspace root with `tool.uv.sources`.
+/// Lock a non-project workspace root with `tool.uv.sources`.
 #[test]
 fn lock_non_project_sources() -> Result<()> {
     let context = uv_test::test_context!("3.12");

crates/uv/tests/it/sync.rs

@@ -1104,9 +1104,9 @@ fn check() -> Result<()> {
     Ok(())
 }
 
-/// Sync development dependencies in a (legacy) non-project workspace root.
+/// Sync development dependencies in a non-project workspace root.
 #[test]
-fn sync_legacy_non_project_dev_dependencies() -> Result<()> {
+fn sync_non_project_dev_dependencies() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
@@ -1185,9 +1185,9 @@ fn sync_legacy_non_project_dev_dependencies() -> Result<()> {
     Ok(())
 }
 
-/// Sync development dependencies in a (legacy) non-project workspace root with `--frozen`.
+/// Sync development dependencies in a non-project workspace root with `--frozen`.
 #[test]
-fn sync_legacy_non_project_frozen() -> Result<()> {
+fn sync_non_project_frozen() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
@@ -1253,9 +1253,9 @@ fn sync_legacy_non_project_frozen() -> Result<()> {
     Ok(())
 }
 
-/// Sync development dependencies in a (legacy) non-project workspace root.
+/// Sync dependency groups in a non-project workspace root.
 #[test]
-fn sync_legacy_non_project_group() -> Result<()> {
+fn sync_non_project_group() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
@@ -1371,11 +1371,11 @@ fn sync_legacy_non_project_group() -> Result<()> {
     Ok(())
 }
 
-/// Sync development dependencies in a (legacy) non-project workspace root with `--frozen`.
+/// Sync development dependencies in a non-project workspace root with `--frozen`.
 ///
 /// Modify the `pyproject.toml` after locking.
 #[test]
-fn sync_legacy_non_project_frozen_modification() -> Result<()> {
+fn sync_non_project_frozen_modification() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     let pyproject_toml = context.temp_dir.child("pyproject.toml");
@@ -4661,9 +4661,9 @@ fn sync_group_member() -> Result<()> {
     Ok(())
 }
 
-/// Sync with `--only-group`, where the group includes a legacy non-`[project]` workspace member.
+/// Sync with `--only-group`, where the group includes a non-`[project]` workspace member.
 #[test]
-fn sync_group_legacy_non_project_member() -> Result<()> {
+fn sync_group_non_project_member() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     // Create a workspace.
@@ -7203,7 +7203,7 @@ fn sync_empty_virtual_environment() -> Result<()> {
 
 /// Test for warnings when `VIRTUAL_ENV` is set but will not be respected.
 #[test]
-fn sync_legacy_non_project_warning() -> Result<()> {
+fn sync_virtual_env_warning() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
     let pyproject_toml = context.temp_dir.child("pyproject.toml");