error: use of reserved field number `5`
  --> testdata/fields/groups/reserved.proto:12:34
   |
 9 |         reserved 5;
   |                  - field number reserved here
10 |         reserved "a";
11 |
12 |         optional int32 bad_tag = 5;
   |                                  ^ used here

error: use of reserved message field name
  --> testdata/fields/groups/reserved.proto:13:24
   |
10 |         reserved "a";
   |                  --- `a` reserved here
11 |
12 |         optional int32 bad_tag = 5;
13 |         optional int32 a = 6;
   |                        ^

encountered 2 errors
