Code review fixes

crates/ra_lsp_server/src/req.rs

@@ -196,3 +196,30 @@ pub struct SourceChange {
     pub workspace_edit: WorkspaceEdit,
     pub cursor_position: Option<TextDocumentPositionParams>,
 }
+
+pub enum InlayHints {}
+
+impl Request for InlayHints {
+    type Params = InlayHintsParams;
+    type Result = Vec<InlayHint>;
+    const METHOD: &'static str = "rust-analyzer/inlayHints";
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct InlayHintsParams {
+    pub text_document: TextDocumentIdentifier,
+}
+
+#[derive(Debug, PartialEq, Eq, Deserialize, Serialize)]
+pub enum InlayKind {
+    LetBindingType,
+    ClosureParameterType,
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub struct InlayHint {
+    pub range: Range,
+    pub kind: InlayKind,
+    pub label: String,
+}