Fix formatting of object and array literal in decorator

.chronus/changes/fix-formatting-object-array-literal-hug-2024-5-13-20-4-7.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+  - "@typespec/compiler"
+---
+
+Fix formatting of object and array literal in decorator to hug parenthesis

packages/compiler/src/formatter/print/printer.ts

@@ -700,12 +700,14 @@ function printCallOrDecoratorArgs(
   }
 
   // So that decorator with single object arguments have ( and { hugging.
-  // @deco({
+  // @deco(#{
   //   value: "foo"
   // })
   const shouldHug =
     node.arguments.length === 1 &&
     (node.arguments[0].kind === SyntaxKind.ModelExpression ||
+      node.arguments[0].kind === SyntaxKind.ObjectLiteral ||
+      node.arguments[0].kind === SyntaxKind.ArrayLiteral ||
       node.arguments[0].kind === SyntaxKind.StringLiteral ||
       node.arguments[0].kind === SyntaxKind.StringTemplateExpression);
 

packages/compiler/test/formatter/formatter.test.ts

@@ -852,6 +852,59 @@ scalar Foo {
       });
     });
   });
+
+  describe("scalar constructor call", () => {
+    it("simple call", async () => {
+      await assertFormat({
+        code: `
+const foo     = utcDateTime.   fromISO(
+  "abc"  );
+`,
+        expected: `
+const foo = utcDateTime.fromISO("abc");
+`,
+      });
+    });
+
+    it("hug object literal", async () => {
+      await assertFormat({
+        code: `
+const foo     = utcDateTime.   fromFoo(#{ name: "abc",
+        multiline1: "abc",
+  multiline2: "abc",
+    multiline3: "abc",  });
+`,
+        expected: `
+const foo = utcDateTime.fromFoo(#{
+  name: "abc",
+  multiline1: "abc",
+  multiline2: "abc",
+  multiline3: "abc",
+});
+`,
+      });
+    });
+
+    it("hug array literal", async () => {
+      await assertFormat({
+        code: `
+const foo     = utcDateTime.   fromFoo(#[
+        "very very long array",
+    "very very long array",
+  "very very long array"
+]);
+`,
+        expected: `
+const foo = utcDateTime.fromFoo(#[
+  "very very long array",
+  "very very long array",
+  "very very long array"
+]);
+`,
+      });
+    });
+  });
+
   describe("comments", () => {
     it("format comment at position 0", async () => {
       await assertFormat({