fix(language_server): always write to memory file system (#15975)

In #15882 we removed the dynamic formatting registration and registered them statically.
LSP Clients could only support static formatting registration and the checks would fail. When someone formats, while not saving, the unsaved changes would disappear.

Removed the checks, so it always saves the content in the file system. Later the Linter will use the file system too when supporting [textDocument/diagnostic](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_diagnostic)

Author: Sysix

crates/oxc_language_server/src/backend.rs

@@ -233,10 +233,8 @@ impl LanguageServer for Backend {
         {
             warn!("sending unregisterCapability.didChangeWatchedFiles failed: {err}");
         }
+        self.file_system.write().await.clear();
 
-        if self.capabilities.get().is_some_and(|option| option.dynamic_formatting) {
-            self.file_system.write().await.clear();
-        }
         Ok(())
     }
 
@@ -466,10 +464,8 @@ impl LanguageServer for Backend {
             return;
         };
 
-        if self.capabilities.get().is_some_and(|option| option.dynamic_formatting) {
-            // saving the file means we can read again from the file system
-            self.file_system.write().await.remove(uri);
-        }
+        // saving the file means we can read again from the file system
+        self.file_system.write().await.remove(uri);
 
         if let Some(diagnostics) = worker.run_diagnostic_on_save(uri, None).await {
             self.client.publish_diagnostics(uri.clone(), diagnostics, None).await;
@@ -487,9 +483,7 @@ impl LanguageServer for Backend {
         };
         let content = params.content_changes.first().map(|c| c.text.clone());
 
-        if self.capabilities.get().is_some_and(|option| option.dynamic_formatting)
-            && let Some(content) = &content
-        {
+        if let Some(content) = &content {
             self.file_system.write().await.set(uri, content.clone());
         }
 
@@ -513,9 +507,7 @@ impl LanguageServer for Backend {
 
         let content = params.text_document.text;
 
-        if self.capabilities.get().is_some_and(|option| option.dynamic_formatting) {
-            self.file_system.write().await.set(uri, content.clone());
-        }
+        self.file_system.write().await.set(uri, content.clone());
 
         if let Some(diagnostics) = worker.run_diagnostic(uri, Some(&content)).await {
             self.client
@@ -534,9 +526,8 @@ impl LanguageServer for Backend {
         let Some(worker) = workers.iter().find(|worker| worker.is_responsible_for_uri(uri)) else {
             return;
         };
-        if self.capabilities.get().is_some_and(|option| option.dynamic_formatting) {
-            self.file_system.write().await.remove(uri);
-        }
+
+        self.file_system.write().await.remove(uri);
         worker.remove_diagnostics(&params.text_document.uri).await;
     }
 

crates/oxc_language_server/src/capabilities.rs

@@ -9,7 +9,6 @@ pub struct Capabilities {
     pub workspace_apply_edit: bool,
     pub workspace_configuration: bool,
     pub dynamic_watchers: bool,
-    pub dynamic_formatting: bool,
 }
 
 impl From<ClientCapabilities> for Capabilities {
@@ -25,13 +24,8 @@ impl From<ClientCapabilities> for Capabilities {
                 watched_files.dynamic_registration.is_some_and(|dynamic| dynamic)
             })
         });
-        let dynamic_formatting = value.text_document.as_ref().is_some_and(|text_document| {
-            text_document.formatting.is_some_and(|formatting| {
-                formatting.dynamic_registration.is_some_and(|dynamic| dynamic)
-            })
-        });
 
-        Self { workspace_apply_edit, workspace_configuration, dynamic_watchers, dynamic_formatting }
+        Self { workspace_apply_edit, workspace_configuration, dynamic_watchers }
     }
 }