[clang-format] Recognize Java logical shift assignment operator

At present, clang-format mangles Java containing logical right shift operators
('>>>=' or '>>>'), splitting them in two, resulting in invalid code:

 public class Minimal {
   public void func(String args) {
     int i = 42;
-    i >>>= 1;
+    i >> >= 1;
     return i;
   }
 }

This adds both forms of logical right shift to the FormatTokenLexer, so
clang-format won't attempt to split them and insert bogus whitespace.

https://reviews.llvm.org/D31652
Patch from Richard Bradfield <bradfier@fstab.me>!

llvm-svn: 299952

clang/lib/Format/FormatTokenLexer.cpp

@@ -84,6 +84,19 @@ void FormatTokenLexer::tryMergePreviousTokens() {
     if (tryMergeTokens(JSRightArrow, TT_JsFatArrow))
       return;
   }
+
+  if (Style.Language == FormatStyle::LK_Java) {
+    static const tok::TokenKind JavaRightLogicalShift[] = {tok::greater,
+                                                           tok::greater,
+                                                           tok::greater};
+    static const tok::TokenKind JavaRightLogicalShiftAssign[] = {tok::greater,
+                                                                 tok::greater,
+                                                                 tok::greaterequal};
+    if (tryMergeTokens(JavaRightLogicalShift, TT_BinaryOperator))
+      return;
+    if (tryMergeTokens(JavaRightLogicalShiftAssign, TT_BinaryOperator))
+      return;
+  }
 }
 
 bool FormatTokenLexer::tryMergeNSStringLiteral() {

clang/unittests/Format/FormatTestJava.cpp

@@ -522,5 +522,17 @@ TEST_F(FormatTestJava, AlignsBlockComments) {
                    "  void f() {}"));
 }
 
+TEST_F(FormatTestJava, RetainsLogicalShifts) {
+    verifyFormat("void f() {\n"
+                 "  int a = 1;\n"
+                 "  a >>>= 1;\n"
+                 "}");
+    verifyFormat("void f() {\n"
+                 "  int a = 1;\n"
+                 "  a = a >>> 1;\n"
+                 "}");
+}
+
+
 } // end namespace tooling
 } // end namespace clang