Merge #5516

5516: Better LSP conformance r=matklad a=vsrs

At the moment rust-analyzer does not fully conform to the LSP. This PR fixes two LSP related issues:

1) rust-analyzer sends predefined server capabilities and does not take supplied client capabilities in mind.
2) rust-analyzer uses dynamic `textDocument/didSave` registration even if the client does not support it.


Co-authored-by: vsrs <[email protected]>

2 files changed, 43 insertions, 32 deletions

diff --git a/crates/rust-analyzer/src/config.rs b/crates/rust-analyzer/src/config.rs
index 8947ccf07..ad62571ef 100644
--- a/crates/rust-analyzer/src/config.rs
+++ b/crates/rust-analyzer/src/config.rs
@@ -128,6 +128,7 @@ pub struct ClientCapsConfig {
     pub hover_actions: bool,
     pub status_notification: bool,
     pub signature_help_label_offsets: bool,
+    pub dynamic_watched_files: bool,
 }
 
 impl Config {
@@ -290,6 +291,13 @@ impl Config {
     }
 
     pub fn update_caps(&mut self, caps: &ClientCapabilities) {
+        if let Some(ws_caps) = caps.workspace.as_ref() {
+            if let Some(did_change_watched_files) = ws_caps.did_change_watched_files.as_ref() {
+                self.client_caps.dynamic_watched_files =
+                    did_change_watched_files.dynamic_registration.unwrap_or(false);
+            }
+        }
+
         if let Some(doc_caps) = caps.text_document.as_ref() {
             if let Some(value) = doc_caps.definition.as_ref().and_then(|it| it.link_support) {
                 self.client_caps.location_link = value;
diff --git a/crates/rust-analyzer/src/main_loop.rs b/crates/rust-analyzer/src/main_loop.rs
index e95d4157c..b44fd9eb4 100644
--- a/crates/rust-analyzer/src/main_loop.rs
+++ b/crates/rust-analyzer/src/main_loop.rs
@@ -106,38 +106,41 @@ impl GlobalState {
             );
         };
 
-        let save_registration_options = lsp_types::TextDocumentSaveRegistrationOptions {
-            include_text: Some(false),
-            text_document_registration_options: lsp_types::TextDocumentRegistrationOptions {
-                document_selector: Some(vec![
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/*.rs".into()),
-                    },
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/Cargo.toml".into()),
-                    },
-                    lsp_types::DocumentFilter {
-                        language: None,
-                        scheme: None,
-                        pattern: Some("**/Cargo.lock".into()),
-                    },
-                ]),
-            },
-        };
-
-        let registration = lsp_types::Registration {
-            id: "textDocument/didSave".to_string(),
-            method: "textDocument/didSave".to_string(),
-            register_options: Some(serde_json::to_value(save_registration_options).unwrap()),
-        };
-        self.send_request::<lsp_types::request::RegisterCapability>(
-            lsp_types::RegistrationParams { registrations: vec![registration] },
-            |_, _| (),
-        );
+        if self.config.client_caps.dynamic_watched_files {
+            let save_registration_options = lsp_types::TextDocumentSaveRegistrationOptions {
+                include_text: Some(false),
+                text_document_registration_options: lsp_types::TextDocumentRegistrationOptions {
+                    document_selector: Some(vec![
+                        lsp_types::DocumentFilter {
+                            language: None,
+                            scheme: None,
+                            pattern: Some("**/*.rs".into()),
+                        },
+                        lsp_types::DocumentFilter {
+                            language: None,
+                            scheme: None,
+                            pattern: Some("**/Cargo.toml".into()),
+                        },
+                        lsp_types::DocumentFilter {
+                            language: None,
+                            scheme: None,
+                            pattern: Some("**/Cargo.lock".into()),
+                        },
+                    ]),
+                },
+            };
+
+            let registration = lsp_types::Registration {
+                id: "textDocument/didSave".to_string(),
+                method: "textDocument/didSave".to_string(),
+                register_options: Some(serde_json::to_value(save_registration_options).unwrap()),
+            };
+
+            self.send_request::<lsp_types::request::RegisterCapability>(
+                lsp_types::RegistrationParams { registrations: vec![registration] },
+                |_, _| (),
+            );
+        }
 
         self.fetch_workspaces();