[clang-format] break after the closing paren of a TypeScript decoration

[krasimir]

Summary

This fixes up a regression we found from
https://reviews.llvm.org/D107267: in specific contexts, clang-format
stopped breaking after the ) in TypeScript decorations. There were no test cases covering this, so I added one.

[MyDeveloperDay]

LGTM, Thanks for picking these up

clang/lib/Format/ContinuationIndenter.cpp

 //===--- ContinuationIndenter.cpp - Format C++ code -----------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// This file implements the continuation indenter.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "ContinuationIndenter.h"
 #include "BreakableToken.h"
 #include "FormatInternal.h"
+#include "FormatToken.h"
 #include "WhitespaceManager.h"
 #include "clang/Basic/OperatorPrecedence.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Format/Format.h"
 #include "llvm/Support/Debug.h"
 
 #define DEBUG_TYPE "format-indenter"
 
if (Previous.ClosesTemplateDeclaration)
       return Style.AlwaysBreakTemplateDeclarations != FormatStyle::BTDS_No;
     if (Previous.is(TT_FunctionAnnotationRParen))
       return true;
     if (Previous.is(TT_LeadingJavaAnnotation) && Current.isNot(tok::l_paren) &&
         Current.isNot(TT_LeadingJavaAnnotation))
       return true;
   }
 
+  // Break after the closing parenthesis of TypeScript decorators.
+  if (Style.Language == FormatStyle::LK_JavaScript &&
+      Previous.is(tok::r_paren) && Previous.is(TT_JavaAnnotation)) {
+    return true;
+  }
+
   // If the return type spans multiple lines, wrap before the function name.
   if (((Current.is(TT_FunctionDeclarationName) &&
         // Don't break before a C# function when no break after return type
         (!Style.isCSharp() ||
          Style.AlwaysBreakAfterReturnType != FormatStyle::RTBS_None) &&
         // Don't always break between a JavaScript `function` and the function
         // name.
         Style.Language != FormatStyle::LK_JavaScript) ||

clang/unittests/Format/FormatTestJS.cpp

EXPECT_EQ("a = function(x) {}\n"
             "\n"
             "function f(x) {}",
             format("a = function(x) {}\n"
                    "\n"
                    "function f(x) {}",
                    getGoogleJSStyleWithColumns(20)));
 }
 
+TEST_F(FormatTestJS, FormatsDecoratedFunctions) {
+  // Regression test: ensure that there is a break before `get`.
+  EXPECT_EQ("class A {\n"
+            "  private p = () => {}\n"
+            "\n"
+            "  @decorated('a')\n"
+            "  get f() {\n"
+            "    return result;\n"
+            "  }\n"
+            "}",
+            format("class A {\n"
+                   "  private p = () => {}\n"
+                   "\n"
+                   "  @decorated('a')\n"
+                   "  get f() {\n"
+                   "    return result;\n"
+                   "  }\n"
+                   "}",
+                   getGoogleJSStyleWithColumns(50)));
+}
+
 TEST_F(FormatTestJS, GeneratorFunctions) {
   verifyFormat("function* f() {\n"
                "  let x = 1;\n"
                "  yield x;\n"
                "  yield* something();\n"
                "  yield [1, 2];\n"
                "  yield {a: 1};\n"
                "}");