[akainth015]

Problem

In trybuild mode (gen_staged_trybuild with a test-mode feature), staged #[cfg(test)] code is kept behind the test-mode feature, and the generated crate makes the original crate's dev-dependencies available under that same feature. However, the generated __deps module only re-exports [dependencies], so spliced code that names a dev-only crate fails to resolve.

For example, with a crate whose test uses a type from a dev-only crate as a type parameter:

[dev-dependencies]
my_test_helper = { path = "../my_test_helper" }

#[cfg(test)]
mod tests {
    #[test]
    fn test() {
        // ...
        let (in_port, input) = process.sim_input_with::<my_test_helper::Codec, _, _, _>();
        // ...
    }
}

the generated code (which starts with use <crate>::__staged::__deps::*;) contains my_test_helper::Codec and fails to compile:

error[E0433]: cannot find module or crate `my_test_helper` in this scope
    |
768 | <my_test_helper::Codec as hydro_lang::__staged::sim::codec::SimCodec<
    |  ^^^^^^^^^^^^^^ use of unresolved module or unlinked crate `my_test_helper`

Change

gen_deps_module now takes the test-mode feature. When set (trybuild mode), it also collects [dev-dependencies] and [target.'cfg(..)'.dev-dependencies], gating each declaration on the test-mode feature and merging it with any regular declaration of the same crate, so the existing merge semantics apply:

Declarations	__deps gate
dev-only	cfg(any(feature = "<test>"))
dev + non-optional regular	ungated (unchanged)
dev + optional regular	cfg(any(<regular gates>, any(feature = "<test>")))
target-specific dev	cfg(all(<target cfg>, any(feature = "<test>")))

The same gate applies to the runtime add_deps_reexport registration, and package renames are handled as for regular dependencies. Since Cargo does not allow optional dev-dependencies, dev declarations are only ever gated on the test-mode feature.

The __deps generated from gen_final! (build.rs) passes no test-mode feature, so its output is unchanged (the staged_deps snapshot is untouched).

Tests

• New unit tests for each row above, package renames, and that dev-dependencies are ignored without a test-mode feature.
• cargo test --workspace --all-targets and cargo clippy --workspace --all-targets -- -D warnings pass.
• Checked end to end with a Hydro sim test like the example above: it fails with the E0433 above against main and passes with this change.

[shadaj]

Awesome!