clang-format: [JS] reserved words in method names.

[mprobst]

Summary

Before:

class X {
  delete () {
    ...
  }
}

After:

class X {
  delete() {
    ...
  }
}

[mprobst]

• move up to support let in methods.

[djasper]

Looks good. Thank you.

lib/Format/TokenAnnotator.cpp

if (Style.Language == FormatStyle::LK_Cpp) {
     if ((Left.is(TT_TemplateString) && Left.TokenText.endswith("${")) ||
         (Right.is(TT_TemplateString) && Right.TokenText.startswith("}")))
       return false;
     if (Left.is(tok::identifier) && Right.is(TT_TemplateString))
       return false;
     if (Right.is(tok::star) &&
         Left.isOneOf(Keywords.kw_function, Keywords.kw_yield))
       return false;
+    // JS methods can use some keywords as names (e.g. `delete()`).
+    if (Right.is(tok::l_paren) && Line.MustBeDeclaration &&
+        Left.Tok.getIdentifierInfo())
+      return false;
     if (Left.isOneOf(Keywords.kw_let, Keywords.kw_var, Keywords.kw_in,
                      Keywords.kw_of, tok::kw_const) &&
         (!Left.Previous || !Left.Previous->is(tok::period)))
       return true;
     if (Left.is(Keywords.kw_as) &&
         Right.isOneOf(tok::l_square, tok::l_brace, tok::l_paren))
       return true;
     if (Left.is(tok::kw_default) && Left.Previous &&

unittests/Format/FormatTestJS.cpp

verifyFormat("x = {\n"
                "};");
   verifyFormat("var struct = 2;");
   verifyFormat("var union = 2;");
   verifyFormat("var interface = 2;");
   verifyFormat("interface = 2;");
   verifyFormat("x = interface instanceof y;");
 }
 
+TEST_F(FormatTestJS, ReservedWordsMethods) {
+  verifyFormat(
+      "class X {\n"
+      "  delete() {\n"
+      "    x();\n"
+      "  }\n"
+      "  interface() {\n"
+      "    x();\n"
+      "  }\n"
+      "  let() {\n"
+      "    x();\n"
+      "  }\n"
+      "}\n");
+}
+
 TEST_F(FormatTestJS, CppKeywords) {
   // Make sure we don't mess stuff up because of C++ keywords.
   verifyFormat("return operator && (aa);");
 }
 
 TEST_F(FormatTestJS, ES6DestructuringAssignment) {
   verifyFormat("var [a, b, c] = [1, 2, 3];");
   verifyFormat("const [a, b, c] = [1, 2, 3];");