Concise mode for parameter hints

This works around VS Code bug where it tries to cram everything in a
tiny popup, and brings experience closer to Intellij.

crates/ra_ide_db/src/feature_flags.rs

@@ -56,6 +56,7 @@ impl Default for FeatureFlags {
             ("completion.insertion.add-call-parenthesis", true),
             ("completion.insertion.add-argument-sippets", true),
             ("completion.enable-postfix", true),
+            ("call-info.full", true),
             ("notifications.workspace-loaded", true),
             ("notifications.cargo-toml-not-found", true),
         ])

crates/rust-analyzer/src/conv.rs

@@ -3,10 +3,10 @@
 
 use lsp_types::{
     self, CreateFile, DiagnosticSeverity, DocumentChangeOperation, DocumentChanges, Documentation,
-    Location, LocationLink, MarkupContent, MarkupKind, Position, Range, RenameFile, ResourceOp,
+    Location, LocationLink, MarkupContent, MarkupKind, ParameterInformation, ParameterLabel,
-    SemanticTokenModifier, SemanticTokenType, SymbolKind, TextDocumentEdit, TextDocumentIdentifier,
+    Position, Range, RenameFile, ResourceOp, SemanticTokenModifier, SemanticTokenType,
-    TextDocumentItem, TextDocumentPositionParams, Url, VersionedTextDocumentIdentifier,
+    SignatureInformation, SymbolKind, TextDocumentEdit, TextDocumentIdentifier, TextDocumentItem,
-    WorkspaceEdit,
+    TextDocumentPositionParams, Url, VersionedTextDocumentIdentifier, WorkspaceEdit,
 };
 use ra_ide::{
     translate_offset_with_edit, CompletionItem, CompletionItemKind, FileId, FilePosition,
@@ -220,17 +220,20 @@ impl Conv for ra_ide::Documentation {
     }
 }
 
-impl Conv for ra_ide::FunctionSignature {
+impl ConvWith<bool> for ra_ide::FunctionSignature {
     type Output = lsp_types::SignatureInformation;
-    fn conv(self) -> Self::Output {
+    fn conv_with(self, concise: bool) -> Self::Output {
-        use lsp_types::{ParameterInformation, ParameterLabel, SignatureInformation};
+        let (label, documentation, params) = if concise {
+            let mut params = self.parameters;
+            if self.has_self_param {
+                params.remove(0);
+            }
+            (params.join(", "), None, params)
+        } else {
+            (self.to_string(), self.doc.map(|it| it.conv()), self.parameters)
+        };
 
-        let label = self.to_string();
+        let parameters: Vec<ParameterInformation> = params
-
-        let documentation = self.doc.map(|it| it.conv());
-
-        let parameters: Vec<ParameterInformation> = self
-            .parameters
             .into_iter()
             .map(|param| ParameterInformation {
                 label: ParameterLabel::Simple(param),

crates/rust-analyzer/src/main_loop/handlers.rs

@@ -459,8 +459,12 @@ pub fn handle_signature_help(
     let _p = profile("handle_signature_help");
     let position = params.try_conv_with(&world)?;
     if let Some(call_info) = world.analysis().call_info(position)? {
-        let active_parameter = call_info.active_parameter.map(|it| it as i64);
+        let concise = !world.analysis().feature_flags().get("call-info.full");
-        let sig_info = call_info.signature.conv();
+        let mut active_parameter = call_info.active_parameter.map(|it| it as i64);
+        if concise && call_info.signature.has_self_param {
+            active_parameter = active_parameter.map(|it| it.saturating_sub(1));
+        }
+        let sig_info = call_info.signature.conv_with(concise);
 
         Ok(Some(req::SignatureHelp {
             signatures: vec![sig_info],

editors/code/package.json

@@ -205,6 +205,10 @@
                             "type": "boolean",
                             "description": "Whether to show postfix snippets like `dbg`, `if`, `not`, etc."
                         },
+                        "call-info.full": {
+                            "type": "boolean",
+                            "description": "Show function name and docs in parameter hints"
+                        },
                         "notifications.workspace-loaded": {
                             "type": "boolean",
                             "description": "Whether to show `workspace loaded` message"