Complete vec macros with square brackets

crates/ra_ide_api/src/completion/complete_macro_in_item_position.rs

@@ -44,6 +44,34 @@ mod tests {
         kind: Macro,
         detail: "macro_rules! foo",
     },
+]"##
+        );
+    }
+
+    #[test]
+    fn completes_vec_macros_with_square_brackets() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /main.rs
+                macro_rules! vec {
+                    () => {}
+                }
+
+                fn foo() {}
+
+                <|>
+                "
+            ),
+            @r##"[
+    CompletionItem {
+        label: "vec!",
+        source_range: [46; 46),
+        delete: [46; 46),
+        insert: "vec![$0]",
+        kind: Macro,
+        detail: "macro_rules! vec",
+    },
 ]"##
         );
     }

crates/ra_ide_api/src/completion/presentation.rs

@@ -108,17 +108,22 @@ impl Completions {
         let ast_node = macro_.source(ctx.db).ast;
         if let Some(name) = name {
             let detail = macro_label(&ast_node);
-            let code_declaration = name + "!";
+
+            let macro_braces_to_insert = match name.as_str() {
+                "vec" => "[$0]",
+                _ => "($0)",
+            };
+            let macro_declaration = name + "!";
 
             let builder = CompletionItem::new(
                 CompletionKind::Reference,
                 ctx.source_range(),
-                &code_declaration,
+                &macro_declaration,
             )
             .kind(CompletionItemKind::Macro)
             .set_documentation(macro_.docs(ctx.db))
             .detail(detail)
-            .insert_snippet(format!("{}($0)", &code_declaration));
+            .insert_snippet(macro_declaration + macro_braces_to_insert);
 
             self.add(builder);
         }