Add txtpb to the list of supported TextProto extensions (#88355)

According to
https://protobuf.dev/reference/protobuf/textformat-spec/#text-format-files,
txtpb is the canonical extension

Co-authored-by: Jing Wang <[email protected]>

Author: jingw

clang/docs/ClangFormat.rst

@@ -54,7 +54,7 @@ to format C/C++/Java/JavaScript/JSON/Objective-C/Protobuf/C# code.
                                        Objective-C: .m .mm
                                        Proto: .proto .protodevel
                                        TableGen: .td
-                                       TextProto: .textpb .pb.txt .textproto .asciipb
+                                       TextProto: .txtpb .textpb .pb.txt .textproto .asciipb
                                        Verilog: .sv .svh .v .vh
     --cursor=<uint>                - The position of the cursor when invoking
                                      clang-format from an editor integration

clang/lib/Format/Format.cpp

@@ -3891,7 +3891,11 @@ static FormatStyle::LanguageKind getLanguageByFileName(StringRef FileName) {
       FileName.ends_with_insensitive(".protodevel")) {
     return FormatStyle::LK_Proto;
   }
-  if (FileName.ends_with_insensitive(".textpb") ||
+  // txtpb is the canonical extension, and textproto is the legacy canonical
+  // extension
+  // https://protobuf.dev/reference/protobuf/textformat-spec/#text-format-files
+  if (FileName.ends_with_insensitive(".txtpb") ||
+      FileName.ends_with_insensitive(".textpb") ||
       FileName.ends_with_insensitive(".pb.txt") ||
       FileName.ends_with_insensitive(".textproto") ||
       FileName.ends_with_insensitive(".asciipb")) {

clang/test/Format/lit.local.cfg

@@ -12,6 +12,7 @@ config.suffixes = [
     ".proto",
     ".protodevel",
     ".pb.txt",
+    ".txtpb",
     ".textproto",
     ".textpb",
     ".asciipb",

clang/tools/clang-format/ClangFormat.cpp

@@ -92,7 +92,7 @@ static cl::opt<std::string> AssumeFileName(
              "  Objective-C: .m .mm\n"
              "  Proto: .proto .protodevel\n"
              "  TableGen: .td\n"
-             "  TextProto: .textpb .pb.txt .textproto .asciipb\n"
+             "  TextProto: .txtpb .textpb .pb.txt .textproto .asciipb\n"
              "  Verilog: .sv .svh .v .vh"),
     cl::init("<stdin>"), cl::cat(ClangFormatCategory));