Elixir 1.19 compatibility: struct update type warnings and test file naming

[nshkrdotcom]

Environment

• Elixir 1.19.4-otp-28
• OTP 28

Description

Compiling on Elixir 1.19 produces numerous "typing violation" warnings due to the new gradual type system's stricter handling of struct updates. The compiler now requires explicit pattern matching to verify a variable's struct type before using struct update syntax.

Warnings

When running mix compile, the following warnings appear:

grpc_server

• lib/grpc/protoc/cli.ex - 6 warnings in parse_param/2 functions
• lib/grpc/protoc/generator.ex - 1 warning in generate_module_definitions/2

grpc_client

• lib/grpc/client/connection.ex - 4 warnings in build_balanced_state/6, build_direct_state/4, build_real_channels/4, connect_real_channel/5

Example warning:
warning: a struct for Protobuf.Protoc.Context is expected on struct update:

%Protobuf.Protoc.Context{ctx | plugins: String.split(plugins, "+")}
but got type:

dynamic()
when defining the variable "ctx", you must also pattern match on "%Protobuf.Protoc.Context{}".

Additional Issues

1. Test type warning: grpc_server/test/grpc/server/adapters/report_exception_test.exs:20 has an unreachable :error clause that triggers a type warning

2. Test file naming: grpc_client/test/grpc/integration/erlpack_notypes.ex uses .ex extension instead of _test.exs, causing Mix to emit a warning about files not matching test patterns

Expected Fix

Add explicit struct pattern matches to function parameters per Elixir 1.19 type system requirements:

# Before
defp parse_param("plugins=" <> plugins, ctx) do

# After
defp parse_param("plugins=" <> plugins, %Context{} = ctx) do

References

- http://elixir-lang.org/blog/2025/10/16/elixir-v1-19-0-released/
- https://hexdocs.pm/elixir/gradual-set-theoretic-types.html

[polvalente]

PRs are welcome fixing this and adding a CI run on 1.19/OTP 28

[nshkrdotcom]

PRs are welcome fixing this and adding a CI run on 1.19/OTP 28

Roger that, PR incoming. Will add 1.19/OTP 28 matrix

[nshkrdotcom]

Opened PR #490 to fix the Elixir 1.19 warnings in grpc (plus the test naming/unreachable clause warnings). Remaining warnings are in protobuf 0.14; tracked in elixir-protobuf/protobuf#427. I can follow up with a dependency bump after 0.16.1 lands.