[clang-format] Consider tok::hashhash in python-style comments

[krasimir]

Summary

We were missing the case when python-style comments in text protos start with ##.

lib/Format/BreakableToken.cpp

default:
     return false;
   }
 }
 
 static StringRef getLineCommentIndentPrefix(StringRef Comment,
                                             const FormatStyle &Style) {
   static const char *const KnownCStylePrefixes[] = {"///<", "//!<", "///", "//",
                                                     "//!"};
-  static const char *const KnownTextProtoPrefixes[] = {"//", "#"};
+  static const char *const KnownTextProtoPrefixes[] = {"//", "#", "##", "###",
+                                                       "####"};
   ArrayRef<const char *> KnownPrefixes(KnownCStylePrefixes);
   if (Style.Language == FormatStyle::LK_TextProto)
     KnownPrefixes = KnownTextProtoPrefixes;
 
   StringRef LongestPrefix;
   for (StringRef KnownPrefix : KnownPrefixes) {
     if (Comment.startswith(KnownPrefix)) {
       size_t PrefixLength = KnownPrefix.size();

lib/Format/FormatTokenLexer.cpp

void FormatTokenLexer::handleTemplateStrings() {
   SourceLocation loc = Offset < Lex->getBuffer().end()
                            ? Lex->getSourceLocation(Offset + 1)
                            : SourceMgr.getLocForEndOfFile(ID);
   resetLexer(SourceMgr.getFileOffset(loc));
 }
 
 void FormatTokenLexer::tryParsePythonComment() {
   FormatToken *HashToken = Tokens.back();
-  if (HashToken->isNot(tok::hash))
+  if (!HashToken->isOneOf(tok::hash, tok::hashhash))
     return;
   // Turn the remainder of this line into a comment.
   const char *CommentBegin =
       Lex->getBufferLocation() - HashToken->TokenText.size(); // at "#"
   size_t From = CommentBegin - Lex->getBuffer().begin();
   size_t To = Lex->getBuffer().find_first_of('\n', From);
   if (To == StringRef::npos)
     To = Lex->getBuffer().size();

unittests/Format/FormatTestTextProto.cpp

verifyFormat("aaaaaaaaaa: 100\n"
                "# Single line comment for stuff here.\n"
                "cccccccccccccccccccccccc: 3849\n"
                "# Multiline comment for stuff here.\n"
                "# Multiline comment for stuff here.\n"
                "# Multiline comment for stuff here.\n"
                "cccccccccccccccccccccccc: 3849");
 }
 
+TEST_F(FormatTestTextProto, UnderstandsHashHashComments) {
+  FormatStyle Style = getGoogleStyle(FormatStyle::LK_TextProto);
+  Style.ColumnLimit = 60; // To make writing tests easier.
+  EXPECT_EQ("aaa: 100\n"
+            "##this is a double-hash comment.\n"
+            "bb: 100\n"
+            "## another double-hash comment.\n"
+            "### a triple-hash comment\n"
+            "cc: 200\n"
+            "#### a quadriple-hash comment\n"
+            "dd: 100\n",
+            format("aaa: 100\n"
+                   "##this is a double-hash comment.\n"
+                   "bb: 100\n"
+                   "## another double-hash comment.\n"
+                   "### a triple-hash comment\n"
+                   "cc: 200\n"
+                   "#### a quadriple-hash comment\n"
+                   "dd: 100\n",
+                   Style));
+}
+
 TEST_F(FormatTestTextProto, FormatsExtensions) {
   verifyFormat("[type] { key: value }");
   verifyFormat("[type] {\n"
                "  keyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy: value\n"
                "}");
   verifyFormat("[type.type] { key: value }");
   verifyFormat("[type.type] < key: value >");
   verifyFormat("[type.type/type.type] { key: value }");