1 files changed, 23 insertions, 21 deletions
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs b/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs
index 4693bdc047f..2fe517fa8cd 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/render/function.rs
@@ -1,12 +1,13 @@
 //! Renderer for function calls.
 
-use hir::{db::HirDatabase, AsAssocItem, HirDisplay};
+use hir::{AsAssocItem, HirDisplay, db::HirDatabase};
 use ide_db::{SnippetCap, SymbolKind};
 use itertools::Itertools;
 use stdx::{format_to, to_lower_snake_case};
-use syntax::{format_smolstr, AstNode, SmolStr, ToSmolStr};
+use syntax::{AstNode, SmolStr, ToSmolStr, format_smolstr};
 
 use crate::{
+    CallableSnippets,
     context::{
         CompleteSemicolon, CompletionContext, DotAccess, DotAccessKind, PathCompletionCtx, PathKind,
     },
@@ -15,9 +16,8 @@ use crate::{
         CompletionRelevanceReturnType, CompletionRelevanceTraitInfo,
     },
     render::{
-        compute_exact_name_match, compute_ref_match, compute_type_match, match_types, RenderContext,
+        RenderContext, compute_exact_name_match, compute_ref_match, compute_type_match, match_types,
     },
-    CallableSnippets,
 };
 
 #[derive(Debug)]
@@ -293,11 +293,7 @@ fn ref_of_param(ctx: &CompletionContext<'_>, arg: &str, ty: &hir::Type) -> &'sta
         for (name, local) in ctx.locals.iter().sorted_by_key(|&(k, _)| k.clone()) {
             if name.as_str() == arg {
                 return if local.ty(ctx.db) == derefed_ty {
-                    if ty.is_mutable_reference() {
-                        "&mut "
-                    } else {
-                        "&"
-                    }
+                    if ty.is_mutable_reference() { "&mut " } else { "&" }
                 } else {
                     ""
                 };
@@ -324,7 +320,9 @@ fn detail(ctx: &CompletionContext<'_>, func: hir::Function) -> String {
         format_to!(detail, "unsafe ");
     }
 
-    format_to!(detail, "fn({})", params_display(ctx, func));
+    detail.push_str("fn(");
+    params_display(ctx, &mut detail, func);
+    detail.push(')');
     if !ret_ty.is_unit() {
         format_to!(detail, " -> {}", ret_ty.display(ctx.db, ctx.display_target));
     }
@@ -346,24 +344,28 @@ fn detail_full(ctx: &CompletionContext<'_>, func: hir::Function) -> String {
     detail
 }
 
-fn params_display(ctx: &CompletionContext<'_>, func: hir::Function) -> String {
+fn params_display(ctx: &CompletionContext<'_>, detail: &mut String, func: hir::Function) {
     if let Some(self_param) = func.self_param(ctx.db) {
+        format_to!(detail, "{}", self_param.display(ctx.db, ctx.display_target));
         let assoc_fn_params = func.assoc_fn_params(ctx.db);
         let params = assoc_fn_params
             .iter()
             .skip(1) // skip the self param because we are manually handling that
             .map(|p| p.ty().display(ctx.db, ctx.display_target));
-        format!(
-            "{}{}",
-            self_param.display(ctx.db, ctx.display_target),
-            params.format_with("", |display, f| {
-                f(&", ")?;
-                f(&display)
-            })
-        )
+        for param in params {
+            format_to!(detail, ", {}", param);
+        }
     } else {
         let assoc_fn_params = func.assoc_fn_params(ctx.db);
-        assoc_fn_params.iter().map(|p| p.ty().display(ctx.db, ctx.display_target)).join(", ")
+        format_to!(
+            detail,
+            "{}",
+            assoc_fn_params.iter().map(|p| p.ty().display(ctx.db, ctx.display_target)).format(", ")
+        );
+    }
+
+    if func.is_varargs(ctx.db) {
+        detail.push_str(", ...");
     }
 }
 
@@ -398,8 +400,8 @@ fn params(
 #[cfg(test)]
 mod tests {
     use crate::{
-        tests::{check_edit, check_edit_with_config, TEST_CONFIG},
         CallableSnippets, CompletionConfig,
+        tests::{TEST_CONFIG, check_edit, check_edit_with_config},
     };
 
     #[test]