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

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.

Reviewed By: MyDeveloperDay

Differential Revision: https://reviews.llvm.org/D108538

clang/lib/Format/ContinuationIndenter.cpp

@@ -14,6 +14,7 @@
 #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"
@@ -491,6 +492,12 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
       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

clang/unittests/Format/FormatTestJS.cpp

@@ -701,6 +701,27 @@ TEST_F(FormatTestJS, FormatsFreestandingFunctions) {
                    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"