add open Cargo.toml action

crates/rust-analyzer/src/handlers.rs

@@ -1322,6 +1322,28 @@ pub(crate) fn handle_open_docs(
     Ok(remote.and_then(|remote| Url::parse(&remote).ok()))
 }
 
+pub(crate) fn handle_open_cargo_toml(
+    snap: GlobalStateSnapshot,
+    params: lsp_ext::OpenCargoTomlParams,
+) -> Result<Option<lsp_types::GotoDefinitionResponse>> {
+    let _p = profile::span("handle_open_cargo_toml");
+    let file_id = from_proto::file_id(&snap, &params.text_document.uri)?;
+    let maybe_cargo_spec = CargoTargetSpec::for_file(&snap, file_id)?;
+    if maybe_cargo_spec.is_none() {
+        return Ok(None);
+    }
+
+    let cargo_spec = maybe_cargo_spec.unwrap();
+    let cargo_toml_path = cargo_spec.workspace_root.join("Cargo.toml");
+    if !cargo_toml_path.exists() {
+        return Ok(None);
+    }
+    let cargo_toml_url = to_proto::url_from_abs_path(&cargo_toml_path);
+    let cargo_toml_location = Location::new(cargo_toml_url, Range::default());
+    let res = lsp_types::GotoDefinitionResponse::from(cargo_toml_location);
+    Ok(Some(res))
+}
+
 fn implementation_title(count: usize) -> String {
     if count == 1 {
         "1 implementation".into()