warning: `import weak` is deprecated in "proto2"
  --> main.proto:6:8
   |
 1 | syntax = "proto2";
   |          -------- syntax specified here
 2 | package buf.test;
...
 5 | import public "b.proto";
 6 | import weak "c.proto";
   |        ^^^^
   = help: deprecated since "proto2", to be removed in Edition 2024
   = help: `import weak` is not implemented correctly in most Protobuf
           implementations

encountered 1 warning
