diff --git a/mlir/lib/Parser/Lexer.cpp b/mlir/lib/Parser/Lexer.cpp
--- a/mlir/lib/Parser/Lexer.cpp
+++ b/mlir/lib/Parser/Lexer.cpp
@@ -83,8 +83,8 @@
       // marker that llvm::MemoryBuffer guarantees will be there.
       if (curPtr - 1 == curBuffer.end())
         return formToken(Token::eof, tokStart);
+      continue;
 
-      LLVM_FALLTHROUGH;
     case ':':
       return formToken(Token::colon, tokStart);
     case ',':
diff --git a/mlir/lib/Parser/Token.h b/mlir/lib/Parser/Token.h
--- a/mlir/lib/Parser/Token.h
+++ b/mlir/lib/Parser/Token.h
@@ -23,7 +23,6 @@
 #define TOK_IDENTIFIER(NAME) NAME,
 #define TOK_LITERAL(NAME) NAME,
 #define TOK_PUNCTUATION(NAME, SPELLING) NAME,
-#define TOK_OPERATOR(NAME, SPELLING) NAME,
 #define TOK_KEYWORD(SPELLING) kw_##SPELLING,
 #include "TokenKinds.def"
   };
@@ -50,7 +49,8 @@
   bool isNot(Kind k) const { return kind != k; }
 
   /// Return true if this token isn't one of the specified kinds.
-  template <typename... T> bool isNot(Kind k1, Kind k2, T... others) const {
+  template <typename... T>
+  bool isNot(Kind k1, Kind k2, T... others) const {
     return !isAny(k1, k2, others...);
   }
 
diff --git a/mlir/lib/Parser/Token.cpp b/mlir/lib/Parser/Token.cpp
--- a/mlir/lib/Parser/Token.cpp
+++ b/mlir/lib/Parser/Token.cpp
@@ -145,9 +145,6 @@
 #define TOK_PUNCTUATION(NAME, SPELLING)                                        \
   case NAME:                                                                   \
     return SPELLING;
-#define TOK_OPERATOR(NAME, SPELLING)                                           \
-  case NAME:                                                                   \
-    return SPELLING;
 #define TOK_KEYWORD(SPELLING)                                                  \
   case kw_##SPELLING:                                                          \
     return #SPELLING;
diff --git a/mlir/lib/Parser/TokenKinds.def b/mlir/lib/Parser/TokenKinds.def
--- a/mlir/lib/Parser/TokenKinds.def
+++ b/mlir/lib/Parser/TokenKinds.def
@@ -11,9 +11,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if !defined(TOK_MARKER) && !defined(TOK_IDENTIFIER) && !defined(TOK_LITERAL)&&\
-    !defined(TOK_PUNCTUATION) && !defined(TOK_OPERATOR) && !defined(TOK_KEYWORD)
-#  error Must define one of the TOK_ macros.
+#if !defined(TOK_MARKER) && !defined(TOK_IDENTIFIER) &&                        \
+    !defined(TOK_LITERAL) && !defined(TOK_PUNCTUATION) &&                      \
+    !defined(TOK_KEYWORD)
+#error Must define one of the TOK_ macros.
 #endif
 
 #ifndef TOK_MARKER
@@ -28,14 +29,10 @@
 #ifndef TOK_PUNCTUATION
 #define TOK_PUNCTUATION(NAME, SPELLING)
 #endif
-#ifndef TOK_OPERATOR
-#define TOK_OPERATOR(NAME, SPELLING)
-#endif
 #ifndef TOK_KEYWORD
 #define TOK_KEYWORD(SPELLING)
 #endif
 
-
 // Markers
 TOK_MARKER(eof)
 TOK_MARKER(error)
@@ -49,34 +46,30 @@
 TOK_IDENTIFIER(exclamation_identifier) // !foo
 
 // Literals
-TOK_LITERAL(floatliteral)               // 2.0
-TOK_LITERAL(integer)                    // 42
-TOK_LITERAL(string)                     // "foo"
-TOK_LITERAL(inttype)                    // i4, si8, ui16
+TOK_LITERAL(floatliteral) // 2.0
+TOK_LITERAL(integer)      // 42
+TOK_LITERAL(string)       // "foo"
+TOK_LITERAL(inttype)      // i4, si8, ui16
 
 // Punctuation.
-TOK_PUNCTUATION(arrow,            "->")
-TOK_PUNCTUATION(at,               "@")
-TOK_PUNCTUATION(colon,            ":")
-TOK_PUNCTUATION(comma,            ",")
-TOK_PUNCTUATION(question,         "?")
-TOK_PUNCTUATION(l_paren,          "(")
-TOK_PUNCTUATION(r_paren,          ")")
-TOK_PUNCTUATION(l_brace,          "{")
-TOK_PUNCTUATION(r_brace,          "}")
-TOK_PUNCTUATION(l_square,         "[")
-TOK_PUNCTUATION(r_square,         "]")
-TOK_PUNCTUATION(less,             "<")
-TOK_PUNCTUATION(greater,          ">")
-TOK_PUNCTUATION(equal,            "=")
-TOK_PUNCTUATION(ellipsis,         "...")
-// TODO: More punctuation.
-
-// Operators.
-TOK_OPERATOR(plus,               "+")
-TOK_OPERATOR(minus,              "-")
-TOK_OPERATOR(star,               "*")
-// TODO: More operator tokens
+TOK_PUNCTUATION(arrow, "->")
+TOK_PUNCTUATION(at, "@")
+TOK_PUNCTUATION(colon, ":")
+TOK_PUNCTUATION(comma, ",")
+TOK_PUNCTUATION(ellipsis, "...")
+TOK_PUNCTUATION(equal, "=")
+TOK_PUNCTUATION(greater, ">")
+TOK_PUNCTUATION(l_brace, "{")
+TOK_PUNCTUATION(l_paren, "(")
+TOK_PUNCTUATION(l_square, "[")
+TOK_PUNCTUATION(less, "<")
+TOK_PUNCTUATION(minus, "-")
+TOK_PUNCTUATION(plus, "+")
+TOK_PUNCTUATION(question, "?")
+TOK_PUNCTUATION(r_brace, "}")
+TOK_PUNCTUATION(r_paren, ")")
+TOK_PUNCTUATION(r_square, "]")
+TOK_PUNCTUATION(star, "*")
 
 // Keywords.  These turn "foo" into Token::kw_foo enums.
 
@@ -122,5 +115,4 @@
 #undef TOK_IDENTIFIER
 #undef TOK_LITERAL
 #undef TOK_PUNCTUATION
-#undef TOK_OPERATOR
 #undef TOK_KEYWORD
diff --git a/mlir/test/IR/parser.mlir b/mlir/test/IR/parser.mlir
--- a/mlir/test/IR/parser.mlir
+++ b/mlir/test/IR/parser.mlir
@@ -1225,3 +1225,9 @@
   return
 }
 
+// CHECK-LABEL: func @zero_whitespace() {
+// CHECK-NEXT: return
+func @zero_whitespace() {
+     // This is a \0 byte.
+  return
+}