[clang-format] Fix end-of-file comments text proto formatting

[krasimir]

Summary

The case of end-of-file comments was formatted badly:

key: value
    # end-of-file comment

This patch fixes that formatting:

key: value
# end-of-file comment

lib/Format/UnwrappedLineParser.cpp

bool MustBeDeclaration =
       !Line->InPPDirective && Style.Language != FormatStyle::LK_JavaScript;
   ScopedDeclarationState DeclarationState(*Line, DeclarationScopeStack,
                                           MustBeDeclaration);
   if (Style.Language == FormatStyle::LK_TextProto)
     parseBracedList();
   else
     parseLevel(/*HasOpeningBrace=*/false);
   // Make sure to format the remaining tokens.
+  //
+  // LK_TextProto is special since its top-level is parsed as the body of a
+  // braced list, which does not necessarily have natural line separators such
+  // as a semicolon. Comments after the last entry that have been determined to
+  // not belong to that line, as in:
+  //   key: value
+  //   // endfile comment
+  // do not have a chance to be put on a line of their own until this point.
+  // Here we add this newline before end-of-file comments.
+  if (Style.Language == FormatStyle::LK_TextProto &&
+      !CommentsBeforeNextToken.empty())
+    addUnwrappedLine();
   flushComments(true);
   addUnwrappedLine();
 }
 
 void UnwrappedLineParser::parseLevel(bool HasOpeningBrace) {
   bool SwitchLabelEncountered = false;
   do {
     tok::TokenKind kind = FormatTok->Tok.getKind();

unittests/Format/FormatTestTextProto.cpp

verifyFormat("repeatedd: [\n"
                "]");
   // "{" is going over the column limit.
   verifyFormat(
       "submessageeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee: {\n"
       "  key: 'aaaaa'\n"
       "}");
 }
 
+TEST_F(FormatTestTextProto, FormatsCommentsAtEndOfFile) {
+  verifyFormat("key: value\n"
+               "# endfile comment");
+  verifyFormat("key: value\n"
+               "// endfile comment");
+  verifyFormat("key: value\n"
+               "// endfile comment 1\n"
+               "// endfile comment 2");
+  verifyFormat("submessage { key: value }\n"
+               "# endfile comment");
+  verifyFormat("submessage <\n"
+               "  key: value\n"
+               "  item {}\n"
+               ">\n"
+               "# endfile comment");
+}
+
 } // end namespace tooling
 } // end namespace clang