[clang-format] Fix parsing of msg{field}-style proto options

[krasimir]

Summary

This patch makes the { in msg_field{field: OK} in a proto option scope be
treated as an assignment operator. Previosly the added test case was formatted
as:

option (MyProto.options) = {
  field_a: OK
  field_b{field_c: OK} field_d: OKOKOK field_e: OK
}

[krasimir]

• Add a msg<field>-style test too

[krasimir]

I think this is ready for a review.

[djasper]

Looks good.

cfe/trunk/lib/Format/TokenAnnotator.cpp

 private:
   /// \brief Gets the precedence (+1) of the given token for binary operators
   /// and other tokens that we treat like binary operators.
   int getCurrentPrecedence() {
     if (Current) {
       const FormatToken *NextNonComment = Current->getNextNonComment();
       if (Current->is(TT_ConditionalExpr))
         return prec::Conditional;
-      if (NextNonComment && NextNonComment->is(tok::colon) &&
-          NextNonComment->is(TT_DictLiteral))
+      if (NextNonComment && Current->is(TT_SelectorName) &&
+          (NextNonComment->is(TT_DictLiteral) ||
+           (Style.Language == FormatStyle::LK_Proto &&
+            NextNonComment->is(tok::less))))
         return prec::Assignment;
       if (Current->is(TT_JsComputedPropertyName))
         return prec::Assignment;
       if (Current->is(TT_LambdaArrow))
         return prec::Comma;
       if (Current->is(TT_JsFatArrow))
         return prec::Assignment;
       if (Current->isOneOf(tok::semi, TT_InlineASMColon, TT_SelectorName) ||

cfe/trunk/unittests/Format/FormatTestProto.cpp

verifyFormat("option (MyProto.options) = {\n"
                "  field_b: \"OK\"\n"
                "  field_c: \"OK\"\n"
                "  msg_field: {field_d: 123}\n"
                "};");
   verifyFormat("option (MyProto.options) = {\n"
                "  field_c: \"OK\"\n"
                "  msg_field{field_d: 123}\n"
                "};");
+  verifyFormat("option (MyProto.options) = {\n"
+               "  field_a: OK\n"
+               "  field_b{field_c: OK}\n"
+               "  field_d: OKOKOK\n"
+               "  field_e: OK\n"
+               "}");
 
   // Support syntax with <> instead of {}.
   verifyFormat("option (MyProto.options) = {\n"
                "  field_c: \"OK\",\n"
                "  msg_field: <field_d: 123>\n"
                "};");
 
   verifyFormat("option (MyProto.options) = {\n"
+               "  field_a: OK\n"
+               "  field_b<field_c: OK>\n"
+               "  field_d: OKOKOK\n"
+               "  field_e: OK\n"
+               "}");
+
+  verifyFormat("option (MyProto.options) = {\n"
                "  msg_field: <>\n"
                "  field_c: \"OK\",\n"
                "  msg_field: <field_d: 123>\n"
                "  field_e: OK\n"
                "  msg_field: <field_d: 12>\n"
                "};");
 
   verifyFormat("option (MyProto.options) = <\n"