Error when tool.uv.sources contains duplicate package names

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

@@ -1,13 +1,13 @@
 use std::collections::BTreeMap;
 use std::path::Path;
 
+use crate::metadata::{LoweredRequirement, MetadataError};
+use crate::Metadata;
 use uv_configuration::SourceStrategy;
 use uv_normalize::{ExtraName, GroupName, PackageName, DEV_DEPENDENCIES};
+use uv_workspace::pyproject::ToolUvSources;
 use uv_workspace::{DiscoveryOptions, ProjectWorkspace};
 
-use crate::metadata::{LoweredRequirement, MetadataError};
-use crate::Metadata;
-
 #[derive(Debug, Clone)]
 pub struct RequiresDist {
     pub name: PackageName,
@@ -71,6 +71,7 @@ impl RequiresDist {
             .as_ref()
             .and_then(|tool| tool.uv.as_ref())
             .and_then(|uv| uv.sources.as_ref())
+            .map(ToolUvSources::inner)
             .unwrap_or(&empty);
 
         let dev_dependencies = {

crates/uv-workspace/src/pyproject.rs

@@ -109,7 +109,7 @@ pub struct Tool {
 pub struct ToolUv {
     /// The sources to use (e.g., workspace members, Git repositories, local paths) when resolving
     /// dependencies.
-    pub sources: Option<BTreeMap<PackageName, Source>>,
+    pub sources: Option<ToolUvSources>,
     /// The workspace definition for the project, if any.
     #[option_group]
     pub workspace: Option<ToolUvWorkspace>,
@@ -245,6 +245,65 @@ pub struct ToolUv {
     pub constraint_dependencies: Option<Vec<pep508_rs::Requirement<VerbatimParsedUrl>>>,
 }
 
+#[derive(Serialize, Default, Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[serde(rename_all = "kebab-case", deny_unknown_fields)]
+pub struct ToolUvSources(BTreeMap<PackageName, Source>);
+
+impl ToolUvSources {
+    /// Returns the underlying `BTreeMap` of package names to sources.
+    pub fn inner(&self) -> &BTreeMap<PackageName, Source> {
+        &self.0
+    }
+
+    /// Convert the [`ToolUvSources`] into its inner `BTreeMap`.
+    #[must_use]
+    pub fn into_inner(self) -> BTreeMap<PackageName, Source> {
+        self.0
+    }
+}
+
+/// Ensure that all keys in the TOML table are unique.
+impl<'de> serde::de::Deserialize<'de> for ToolUvSources {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::de::Deserializer<'de>,
+    {
+        struct SourcesVisitor;
+
+        impl<'de> serde::de::Visitor<'de> for SourcesVisitor {
+            type Value = ToolUvSources;
+
+            fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+                formatter.write_str("a map with unique keys")
+            }
+
+            fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+            where
+                M: serde::de::MapAccess<'de>,
+            {
+                let mut sources = BTreeMap::new();
+                while let Some((key, value)) = access.next_entry::<PackageName, Source>()? {
+                    match sources.entry(key) {
+                        std::collections::btree_map::Entry::Occupied(entry) => {
+                            return Err(serde::de::Error::custom(format!(
+                                "duplicate sources for package `{}`",
+                                entry.key()
+                            )));
+                        }
+                        std::collections::btree_map::Entry::Vacant(entry) => {
+                            entry.insert(value);
+                        }
+                    }
+                }
+                Ok(ToolUvSources(sources))
+            }
+        }
+
+        deserializer.deserialize_map(SourcesVisitor)
+    }
+}
+
 #[derive(Serialize, Deserialize, OptionsMetadata, Default, Debug, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 #[serde(rename_all = "kebab-case", deny_unknown_fields)]

crates/uv-workspace/src/workspace.rs

@@ -14,7 +14,7 @@ use uv_fs::{Simplified, CWD};
 use uv_normalize::{GroupName, PackageName, DEV_DEPENDENCIES};
 use uv_warnings::{warn_user, warn_user_once};
 
-use crate::pyproject::{Project, PyProjectToml, Source, ToolUvWorkspace};
+use crate::pyproject::{Project, PyProjectToml, Source, ToolUvSources, ToolUvWorkspace};
 
 #[derive(thiserror::Error, Debug)]
 pub enum WorkspaceError {
@@ -234,6 +234,7 @@ impl Workspace {
                 .clone()
                 .and_then(|tool| tool.uv)
                 .and_then(|uv| uv.sources)
+                .map(ToolUvSources::into_inner)
                 .unwrap_or_default();
 
             // Set the `pyproject.toml` for the member.
@@ -741,6 +742,7 @@ impl Workspace {
             .clone()
             .and_then(|tool| tool.uv)
             .and_then(|uv| uv.sources)
+            .map(ToolUvSources::into_inner)
             .unwrap_or_default();
 
         Ok(Workspace {

crates/uv/tests/lock.rs

@@ -12628,3 +12628,75 @@ fn lock_request_requires_python() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn lock_duplicate_sources() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "projeect"
+        version = "0.1.0"
+        dependencies = ["python-multipart"]
+
+        [tool.uv.sources]
+        python-multipart = { url = "https://files.pythonhosted.org/packages/3d/47/444768600d9e0ebc82f8e347775d24aef8f6348cf00e9fa0e81910814e6d/python_multipart-0.0.9-py3-none-any.whl" }
+        python-multipart = { url = "https://files.pythonhosted.org/packages/c0/3e/9fbfd74e7f5b54f653f7ca99d44ceb56e718846920162165061c4c22b71a/python_multipart-0.0.8-py3-none-any.whl" }
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    warning: Failed to parse `pyproject.toml` during settings discovery:
+      TOML parse error at line 9, column 9
+        |
+      9 |         python-multipart = { url = "https://files.pythonhosted.org/packages/c0/3e/9fbfd74e7f5b54f653f7ca99d44ceb56e718846920162165061c4c22b71a/python_multipart-0.0.8-py3-none-any.whl" }
+        |         ^
+      duplicate key `python-multipart` in table `tool.uv.sources`
+
+    error: Failed to parse: `pyproject.toml`
+      Caused by: TOML parse error at line 9, column 9
+      |
+    9 |         python-multipart = { url = "https://files.pythonhosted.org/packages/c0/3e/9fbfd74e7f5b54f653f7ca99d44ceb56e718846920162165061c4c22b71a/python_multipart-0.0.8-py3-none-any.whl" }
+      |         ^
+    duplicate key `python-multipart` in table `tool.uv.sources`
+
+    "###);
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        dependencies = ["python-multipart"]
+
+        [tool.uv.sources]
+        python-multipart = { url = "https://files.pythonhosted.org/packages/3d/47/444768600d9e0ebc82f8e347775d24aef8f6348cf00e9fa0e81910814e6d/python_multipart-0.0.9-py3-none-any.whl" }
+        python_multipart = { url = "https://files.pythonhosted.org/packages/c0/3e/9fbfd74e7f5b54f653f7ca99d44ceb56e718846920162165061c4c22b71a/python_multipart-0.0.8-py3-none-any.whl" }
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Failed to parse: `pyproject.toml`
+      Caused by: TOML parse error at line 7, column 9
+      |
+    7 |         [tool.uv.sources]
+      |         ^^^^^^^^^^^^^^^^^
+    duplicate sources for package `python-multipart`
+
+    "###);
+
+    Ok(())
+}