Index: lib/Format/UnwrappedLineParser.cpp
===================================================================
--- lib/Format/UnwrappedLineParser.cpp
+++ lib/Format/UnwrappedLineParser.cpp
@@ -2018,6 +2018,10 @@
       FormatTok->isOneOf(tok::colon, tok::question))
     return false;
 
+  // In protobuf, "enum" can be used as a field name.
+  if (Style.Language == FormatStyle::LK_Proto && FormatTok->is(tok::equal))
+    return false;
+
   // Eat up enum class ...
   if (FormatTok->Tok.is(tok::kw_class) || FormatTok->Tok.is(tok::kw_struct))
     nextToken();
Index: unittests/Format/FormatTestProto.cpp
===================================================================
--- unittests/Format/FormatTestProto.cpp
+++ unittests/Format/FormatTestProto.cpp
@@ -107,6 +107,12 @@
                "};");
 }
 
+TEST_F(FormatTestProto, EnumAsFieldName) {
+  verifyFormat("message SomeMessage {\n"
+               "  required int32 enum = 1;\n"
+               "}");
+}
+
 TEST_F(FormatTestProto, UnderstandsReturns) {
   verifyFormat("rpc Search(SearchRequest) returns (SearchResponse);");
 }