Avoid flattened source-distribution deserialization

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

@@ -5446,8 +5446,7 @@ enum GitSourceKind {
 }
 
 /// Inspired by: <https://discuss.python.org/t/lock-files-again-but-this-time-w-sdists/46593>
-#[derive(Clone, Debug, serde::Deserialize, PartialEq, Eq)]
-#[serde(rename_all = "kebab-case")]
+#[derive(Clone, Debug, PartialEq, Eq)]
 struct SourceDistMetadata {
     /// A hash of the source distribution.
     hash: Option<Hash>,
@@ -5456,33 +5455,69 @@ struct SourceDistMetadata {
     /// This is only present for source distributions that come from registries.
     size: Option<u64>,
     /// The upload time of the source distribution.
-    #[serde(alias = "upload_time")]
     upload_time: Option<Timestamp>,
 }
 
 /// A URL or file path where the source dist that was
 /// locked against was found. The location does not need to exist in the
 /// future, so this should be treated as only a hint to where to look
 /// and/or recording where the source dist file originally came from.
-#[derive(Clone, Debug, serde::Deserialize, PartialEq, Eq)]
-#[serde(from = "SourceDistWire")]
+#[derive(Clone, Debug, PartialEq, Eq)]
 enum SourceDist {
     Url {
         url: UrlString,
-        #[serde(flatten)]
         metadata: SourceDistMetadata,
     },
     Path {
         path: Box<Path>,
-        #[serde(flatten)]
         metadata: SourceDistMetadata,
     },
     Metadata {
-        #[serde(flatten)]
         metadata: SourceDistMetadata,
     },
 }
 
+impl<'de> serde::Deserialize<'de> for SourceDist {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        #[derive(serde::Deserialize)]
+        #[serde(rename_all = "kebab-case")]
+        struct Fields {
+            url: Option<UrlString>,
+            path: Option<PortablePathBuf>,
+            hash: Option<Hash>,
+            size: Option<u64>,
+            #[serde(alias = "upload_time")]
+            upload_time: Option<Timestamp>,
+        }
+
+        let Fields {
+            url,
+            path,
+            hash,
+            size,
+            upload_time,
+        } = serde::Deserialize::deserialize(deserializer)?;
+
+        let metadata = SourceDistMetadata {
+            hash,
+            size,
+            upload_time,
+        };
+
+        Ok(match (url, path) {
+            (Some(url), _) => Self::Url { url, metadata },
+            (None, Some(path)) => Self::Path {
+                path: path.into(),
+                metadata,
+            },
+            (None, None) => Self::Metadata { metadata },
+        })
+    }
+}
+
 impl SourceDist {
     fn filename(&self) -> Option<Cow<'_, str>> {
         match self {
@@ -5741,38 +5776,6 @@ impl SourceDist {
     }
 }
 
-#[derive(Clone, Debug, serde::Deserialize)]
-#[serde(untagged, rename_all = "kebab-case")]
-enum SourceDistWire {
-    Url {
-        url: UrlString,
-        #[serde(flatten)]
-        metadata: SourceDistMetadata,
-    },
-    Path {
-        path: PortablePathBuf,
-        #[serde(flatten)]
-        metadata: SourceDistMetadata,
-    },
-    Metadata {
-        #[serde(flatten)]
-        metadata: SourceDistMetadata,
-    },
-}
-
-impl From<SourceDistWire> for SourceDist {
-    fn from(wire: SourceDistWire) -> Self {
-        match wire {
-            SourceDistWire::Url { url, metadata } => Self::Url { url, metadata },
-            SourceDistWire::Path { path, metadata } => Self::Path {
-                path: path.into(),
-                metadata,
-            },
-            SourceDistWire::Metadata { metadata } => Self::Metadata { metadata },
-        }
-    }
-}
-
 impl From<GitReference> for GitSourceKind {
     fn from(value: GitReference) -> Self {
         match value {