Fix Elixir 1.19 warnings #427

nshkrdotcom · 2026-01-09T21:14:39Z

Summary

fix Elixir 1.19 compile/test warnings by updating struct updates, property tests, and dynamic module calls
move preferred_cli_env into cli/0
add Elixir 1.19/OTP 28 to CI matrix

Testing

not run (not requested)

whatyouhide · 2026-01-14T10:53:30Z

mix.exs


  @source_url "https://github.com/elixir-protobuf/protobuf"
-  @version "0.16.0"
+  @version "0.16.1"


We don't release versions in PRs. I'll revert this and release when appropriate.

mix.exs

whatyouhide

Thanks for tackling this!

whatyouhide · 2026-01-14T10:54:29Z

test/protobuf/json/rfc3339_test.exs

+                nanos_raw <- integer(1..999_999_999) do
+        max_range = String.to_integer(String.duplicate("9", digits_count))
+        scale = round(:math.pow(10, 9 - digits_count))
+        nanos = rem(nanos_raw - 1, max_range) + 1
+        scaled_nanos = nanos * scale
+
+        real_nanos =
+          String.to_integer(String.pad_trailing(Integer.to_string(scaled_nanos), 9, "0"))


Can you elaborate on the changes here?

I moved the calcs into the test body instead of the generator clause, which were causing the warnings on Elixir 1.19.4

RFC3339 Property Test Changes

The Warning

warning: this clause in cond will always match: max_range = String.to_integer(String.duplicate("9", digits_count)) since it has type: integer() where "digits_count" was given the type: # type: dynamic() # from: test/protobuf/json/rfc3339_test.exs:66 digits_count = generated_value where "max_range" was given the type: # type: integer() # from: test/protobuf/json/rfc3339_test.exs:67:27 max_range = String.to_integer(String.duplicate("9", digits_count)) typing violation found at: 67 │ max_range = String.to_integer(String.duplicate("9", digits_count)),

A second warning with the same shape is emitted for nanos = nanos * round(:math.pow(10, 9 - digits_count)) in the same check all, and the same pair of warnings appears in the encode property.

Why Elixir 1.19 Warns About This

Elixir 1.19’s new type-system warnings include detection of always-true/never-true clauses in cond/case (see the set-theoretic type system work). ExUnitProperties.check_all expands the generator list into a cond-like pipeline. When you use bindings like max_range = ... or rebinding nanos = ... inside the generator list, those become cond clauses that are always truthy, so the compiler flags them as “will always match.” This is the same warning reported by StreamData users in property tests with check all bindings.

What The Fix Does

In test/protobuf/json/rfc3339_test.exs, I made the generator list “pure generators” only (digits_count and nanos_raw), and moved the deterministic computations into the test body. That avoids = bindings inside the generator list, which is what triggers the cond warning. I also map nanos_raw into the desired 1..max_range range via rem, then apply the same scaling math as before.

Semantic Equivalence

The set of values covered is the same: nanos still ranges over 1..max_range, and scaled_nanos is still nanos * 10^(9 - digits_count) before converting into real_nanos. The only behavioral change is distribution (a slight modulo bias for the 6-digit case) and potentially different shrinking paths, which doesn’t affect correctness of the property. Coverage remains effectively the same.

References

https://github.com/elixir-lang/elixir/blob/v1.19.0/CHANGELOG.md

check all and gen all generate type warnings on Elixir 1.18.2 whatyouhide/stream_data#207

Set-theoretic types: inference of all language constructs elixir-lang/elixir#14558

whatyouhide · 2026-01-14T10:54:35Z

test/protobuf/protoc/cli_integration_test.exs


-    message = base_mod.put_extension(message, Bugs.PbExtension, :top_first_name, "TFN")
-    assert base_mod.get_extension(message, Bugs.PbExtension, :top_first_name) == "TFN"
+    message = apply(base_mod, :put_extension, [message, Bugs.PbExtension, :top_first_name, "TFN"])


Why did we change this?

Elixir 1.19.4 was warning about syntax when calling functions on a module stored in a var

Dynamic Module Call Changes

The Warning

warning: Bugs.Base.put_extension/4 is undefined (module Bugs.Base is not available or is yet to be defined) │ 260 │ message = base_mod.put_extension(message, Bugs.PbExtension, :top_first_name, "TFN") │ ~ └─ test/protobuf/protoc/cli_integration_test.exs:260:24: Protobuf.Protoc.CLIIntegrationTest."test multiple extensions defined in different scopes"/1

A corresponding warning is emitted for Bugs.Base.get_extension/3.

Why Elixir 1.19 Warns About This

In this test, base_mod is bound via Bugs.Base = base_mod, so the compiler can infer that base_mod is the Bugs.Base module. With Elixir 1.19’s expanded type/remote-call analysis, the compiler attempts to resolve the remote call at compile time and warns if that module (generated later at runtime) is not yet available. This is part of the same type system work that started tracking variable types and remote calls more aggressively, and it surfaces as "module is not available or is yet to be defined."

The Recommended Fix

apply/3 is the standard way to invoke a function on a module that is only known at runtime. It keeps the call dynamic and avoids compile-time resolution, while preserving runtime behavior. In this case, the module is generated during the test run (compile_file_and_clean_modules_on_exit), so apply/3 is the appropriate pattern.

References

https://github.com/elixir-lang/elixir/blob/v1.19.0/CHANGELOG.md

Dynamic module function call leads to compiler warning elixir-lang/elixir#14739

Set-theoretic types: inference of all language constructs elixir-lang/elixir#14558

https://hexdocs.pm/elixir/Kernel.html#apply/3

whatyouhide · 2026-01-14T10:54:47Z

README.md

 def deps do
  [
-    {:protobuf, "~> 0.15.0"}
+    {:protobuf, "~> 0.16.1"}


Let's revert this too please.

I pushed but changed it to 0.16.0, not 0.15.0. Would you prefer 0.15.0? I'll change it according to your req's

whatyouhide · 2026-01-14T10:54:53Z

README.md


    ```bash
-    $ mix escript.install hex protobuf 0.14.0
+    $ mix escript.install hex protobuf 0.16.1


I pushed this, but again, I reverted this to 0.16.0 since that's the most recent release. If that's wrong and needs to go back to 0.14.0, LMK and I'll fix it. Thanks.

whatyouhide · 2026-01-14T10:55:22Z

CHANGELOG.md

+## v0.16.1
+
+### Enhancements
+
+  * Add Elixir 1.19/OTP 28 to the CI matrix.
+  * Update README version references to the 0.16.x series.
+
+### Bug fixes
+
+  * Fix compilation warnings on Elixir 1.19+ by using struct pattern matching and map update syntax.
+  * Fix `preferred_cli_env` deprecation warning by moving configuration into `cli/0`.
+  * Fix Elixir 1.19 warnings in RFC3339 property tests and protoc CLI integration tests.
+


Let's remove the CHANGELOG please, most of these are not information that users will do anything with.

nshkrdotcom · 2026-01-16T22:27:40Z

Additional Notes

The struct-update changes in lib/protobuf/dsl.ex, lib/protobuf/protoc/cli.ex, lib/protobuf/protoc/generator.ex, and lib/protobuf/protoc/generator/extension.ex are directly responding to new 1.19 type warnings like “a struct for Protobuf.FieldProps is expected on struct update”; adding %Struct{} = var patterns and switching to %{var | ...} keeps behavior intact while satisfying the type checker.
mix.exs now defines def cli/0 with preferred_envs, matching the Mix 1.19 deprecation warning about :preferred_cli_env in def project.
.github/workflows/main.yml adds an Elixir 1.19.4 / OTP 28 matrix entry to validate the warnings are gone in CI.
No changes in lib/protobuf/encoder.ex or lib/protobuf/decoder.ex in c3d0d73.
Verification: on base 6379e87, Elixir 1.19.4 emits the two warning classes above; on this branch, ASDF_ELIXIR_VERSION=1.19.4-otp-28 mix test test/protobuf/json/rfc3339_test.exs and ASDF_ELIXIR_VERSION=1.19.4-otp-28 mix test test/protobuf/protoc/cli_integration_test.exs run clean.

whatyouhide · 2026-01-19T08:34:18Z

Thanks @nshkrdotcom 🫶

nshkrdotcom added 2 commits January 9, 2026 11:12

Fix Elixir 1.19 warnings

c3d0d73

Release v0.16.1

250e469

whatyouhide reviewed Jan 14, 2026

View reviewed changes

mix.exs Outdated Show resolved Hide resolved

Apply suggestions from code review

1860c06

whatyouhide requested changes Jan 14, 2026

View reviewed changes

Revert CHANGELOG.md and README.md

533d766

nshkrdotcom requested a review from whatyouhide January 14, 2026 22:08

whatyouhide merged commit 4328993 into elixir-protobuf:main Jan 19, 2026
5 checks passed

Fix Elixir 1.19 warnings #427

Fix Elixir 1.19 warnings #427

Conversation

nshkrdotcom commented Jan 9, 2026

Summary

Testing

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

whatyouhide left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

RFC3339 Property Test Changes

The Warning

Why Elixir 1.19 Warns About This

What The Fix Does

Semantic Equivalence

References

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Dynamic Module Call Changes

The Warning

Why Elixir 1.19 Warns About This

The Recommended Fix

References

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

nshkrdotcom commented Jan 16, 2026

Additional Notes

Uh oh!

Uh oh!

whatyouhide commented Jan 19, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants