clang-format: [JS] do not wrap after `asserts`

`asserts` is a pseudo keyword in TypeScript used in return types.
Wrapping after it triggers automatic semicolon insertion, which
breaks the code semantics/syntax.

`asserts` is different from other pseudo keywords in that it is
specific to TS and only carries meaning in a very specific location.
Thus introducing a token type is probably overkill.

Differential Revision: https://reviews.llvm.org/D100953

clang/lib/Format/TokenAnnotator.cpp

@@ -3853,6 +3853,9 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
          Left.isOneOf(tok::r_square, tok::r_paren)) &&
         Right.isOneOf(tok::l_square, tok::l_paren))
       return false; // Otherwise automatic semicolon insertion would trigger.
+    if (NonComment && NonComment->is(tok::identifier) &&
+        NonComment->TokenText == "asserts")
+      return false;
     if (Left.is(TT_JsFatArrow) && Right.is(tok::l_brace))
       return false;
     if (Left.is(TT_JsTypeColon))

clang/unittests/Format/FormatTestJS.cpp

@@ -2589,5 +2589,20 @@ TEST_F(FormatTestJS, DeclaredFields) {
                "}\n");
 }
 
+TEST_F(FormatTestJS, NoBreakAfterAsserts) {
+  verifyFormat(
+      "interface Assertable<State extends {}> {\n"
+      "  assert<ExportedState extends {}, DependencyState extends State = "
+      "State>(\n"
+      "      callback: Callback<ExportedState, DependencyState>):\n"
+      "      asserts this is ExtendedState<DependencyState&ExportedState>;\n"
+      "}\n",
+      "interface Assertable<State extends {}> {\n"
+      "  assert<ExportedState extends {}, DependencyState extends State = "
+      "State>(callback: Callback<ExportedState, DependencyState>): asserts "
+      "this is ExtendedState<DependencyState&ExportedState>;\n"
+      "}\n");
+}
+
 } // namespace format
 } // end namespace clang