Merge #6519

6519: Add "Open Cargo.toml" action r=matklad a=p3achyjr

## What is it?

This adds an "open cargo.toml" action from the vscode shell, resolves #6462 

## Test

Ran ```cargo xtask install --server``` and ```cargo xtask install --client```, then ```Developer: Reload Window```.

![image](https://user-images.githubusercontent.com/8763808/98614382-2a578f00-22ad-11eb-9811-4a72a54ff6fb.png)

When clicked:

![image](https://user-images.githubusercontent.com/8763808/98618176-77d7fa00-22b5-11eb-8788-35256542f3a6.png)


Co-authored-by: Anatol Liu <axlui@anatols-mbp.lan>

crates/rust-analyzer/src/config.rs

@@ -398,13 +398,10 @@ impl Config {
             }
 
             if let Some(code_action) = &doc_caps.code_action {
-                match (code_action.data_support, &code_action.resolve_support) {
-                    (Some(true), Some(resolve_support)) => {
-                        if resolve_support.properties.iter().any(|it| it == "edit") {
-                            self.client_caps.code_action_resolve = true;
-                        }
+                if let Some(resolve_support) = &code_action.resolve_support {
+                    if resolve_support.properties.iter().any(|it| it == "edit") {
+                        self.client_caps.code_action_resolve = true;
                     }
-                    _ => (),
                 }
             }
         }

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()

crates/rust-analyzer/src/lsp_ext.rs

@@ -354,3 +354,17 @@ impl Request for ExternalDocs {
     type Result = Option<lsp_types::Url>;
     const METHOD: &'static str = "experimental/externalDocs";
 }
+
+pub enum OpenCargoToml {}
+
+impl Request for OpenCargoToml {
+    type Params = OpenCargoTomlParams;
+    type Result = Option<lsp_types::GotoDefinitionResponse>;
+    const METHOD: &'static str = "experimental/openCargoToml";
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct OpenCargoTomlParams {
+    pub text_document: TextDocumentIdentifier,
+}

crates/rust-analyzer/src/main_loop.rs

@@ -438,6 +438,7 @@ impl GlobalState {
             .on::<lsp_ext::CodeActionResolveRequest>(handlers::handle_code_action_resolve)
             .on::<lsp_ext::HoverRequest>(handlers::handle_hover)
             .on::<lsp_ext::ExternalDocs>(handlers::handle_open_docs)
+            .on::<lsp_ext::OpenCargoToml>(handlers::handle_open_cargo_toml)
             .on::<lsp_types::request::OnTypeFormatting>(handlers::handle_on_type_formatting)
             .on::<lsp_types::request::DocumentSymbolRequest>(handlers::handle_document_symbol)
             .on::<lsp_types::request::WorkspaceSymbol>(handlers::handle_workspace_symbol)