`message_len` is declared `const fn` but calls non-const functions, causing E0015 build failures

[OleFass]

After upgrading from yellowstone-grpc-proto = 5.1.0 to yellowstone-grpc-proto = 6.1.0 the build fails with:

error[E0015]: cannot call non-const fn `key_len` in constant functions
  ...
  key_len(tag) + encoded_len_varint(len as u64) + len
  ^^^^^^^^^^^^
error[E0015]: cannot call non-const fn `encoded_len_varint` in constant functions
  ...
  key_len(tag) + encoded_len_varint(len as u64) + len
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The generated message_len in
src/plugin/filter/message.rs:40 is declared pub const fn, but it invokes encoded_len_varint, which is not a const fn. Rust rejects any non-const calls inside a const fn (E0015).

Reproduction:

Add yellowstone-grpc-proto = "6.1.0" to your Cargo.toml.

Run cargo build.

Observe the two E0015 errors above.

Expected behavior:
Codegen should either:

Declare message_len as a plain fn (remove const)

Either change would allow downstream crates to compile without patching or downgrading.

Environment:

rustc 1.84.0 (stable)
yellowstone-grpc-proto 6.1.0

Suggested fix:
In src/plugin/filter/message.rs, change:

-pub const fn message_len(tag: u32, len: usize) -> usize {
+pub fn message_len(tag: u32, len: usize) -> usize {

[fanatid]

1. you need to bump prost in your Cargo.lock file to 0.13.5 (https://github.com/tokio-rs/prost/pull/1199/files change encoded_len_varint to const fn and included only in 0.13.5)
2. yellowstone-grpc repo needs bump prost to 0.13.5 in Cargo.toml (it's already bumped to 0.13.5 in Cargo.lock) and probably publish patch releases (?)

[OleFass]

Thank you!
As a beginner in Rust it is sometimes hard to navigate the error messages.