Add a dedicated error for `include = "dev"` with `tool.uv.dev-dependencies` (#9173)

## Summary

This isn't really spec-compliant, so we already don't allow it -- this
just adds a better error message and an explicit test for it.

crates/uv-distribution/src/metadata/requires_dist.rs

@@ -132,7 +132,8 @@ impl RequiresDist {
 
             // Resolve any `include-group` entries in `dependency-groups`.
             let dependency_groups =
-                FlatDependencyGroups::from_dependency_groups(&dependency_groups)?
+                FlatDependencyGroups::from_dependency_groups(&dependency_groups)
+                    .map_err(|err| err.with_dev_dependencies(dev_dependencies))?
                     .into_iter()
                     .chain(
                         // Only add the `dev` group if `dev-dependencies` is defined.

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

@@ -114,7 +114,8 @@ impl<'env> InstallTarget<'env> {
                 // Merge any overlapping groups.
                 let mut map = BTreeMap::new();
                 for (name, dependencies) in
-                    FlatDependencyGroups::from_dependency_groups(&dependency_groups)?
+                    FlatDependencyGroups::from_dependency_groups(&dependency_groups)
+                        .map_err(|err| err.with_dev_dependencies(dev_dependencies))?
                         .into_iter()
                         .chain(
                             // Only add the `dev` group if `dev-dependencies` is defined.

crates/uv-workspace/src/dependency_groups.rs

@@ -4,7 +4,7 @@ use std::str::FromStr;
 use thiserror::Error;
 use tracing::warn;
 
-use uv_normalize::GroupName;
+use uv_normalize::{GroupName, DEV_DEPENDENCIES};
 use uv_pep508::Pep508Error;
 use uv_pypi_types::VerbatimParsedUrl;
 
@@ -126,10 +126,30 @@ pub enum DependencyGroupError {
     ),
     #[error("Failed to find group `{0}` included by `{1}`")]
     GroupNotFound(GroupName, GroupName),
+    #[error("Group `{0}` includes the `dev` group (`include = \"dev\"`), but only `tool.uv.dev-dependencies` was found. To reference the `dev` group via an `include`, remove the `tool.uv.dev-dependencies` section and add any development dependencies to the `dev` entry in the `[dependency-groups]` table instead.")]
+    DevGroupInclude(GroupName),
     #[error("Detected a cycle in `dependency-groups`: {0}")]
     DependencyGroupCycle(Cycle),
 }
 
+impl DependencyGroupError {
+    /// Enrich a [`DependencyGroupError`] with the `tool.uv.dev-dependencies` metadata, if applicable.
+    #[must_use]
+    pub fn with_dev_dependencies(
+        self,
+        dev_dependencies: Option<&Vec<uv_pep508::Requirement<VerbatimParsedUrl>>>,
+    ) -> Self {
+        match self {
+            DependencyGroupError::GroupNotFound(group, parent)
+                if dev_dependencies.is_some() && group == *DEV_DEPENDENCIES =>
+            {
+                DependencyGroupError::DevGroupInclude(parent)
+            }
+            _ => self,
+        }
+    }
+}
+
 /// A cycle in the `dependency-groups` table.
 #[derive(Debug)]
 pub struct Cycle(Vec<GroupName>);

crates/uv-workspace/src/workspace.rs

@@ -343,7 +343,8 @@ impl Workspace {
 
             // Resolve any `include-group` entries in `dependency-groups`.
             let dependency_groups =
-                FlatDependencyGroups::from_dependency_groups(&dependency_groups)?;
+                FlatDependencyGroups::from_dependency_groups(&dependency_groups)
+                    .map_err(|err| err.with_dev_dependencies(dev_dependencies))?;
 
             // Concatenate the two sets of requirements.
             let dev_dependencies = dependency_groups

crates/uv/tests/it/lock.rs

@@ -19096,6 +19096,40 @@ fn lock_group_include_cycle() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn lock_group_include_dev() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = []
+
+        [tool.uv]
+        dev-dependencies = ["anyio"]
+
+        [dependency-groups]
+        foo = ["typing-extensions", {include-group = "dev"}]
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+      × Failed to build `project @ file://[TEMP_DIR]/`
+      ╰─▶ Group `foo` includes the `dev` group (`include = "dev"`), but only `tool.uv.dev-dependencies` was found. To reference the `dev` group via an `include`, remove the `tool.uv.dev-dependencies` section and add any development dependencies to the `dev` entry in the `[dependency-groups]` table instead.
+    "###);
+
+    Ok(())
+}
+
 #[test]
 fn lock_group_include_missing() -> Result<()> {
     let context = TestContext::new("3.12");