Add init function for fetchers

[RossComputerGuy]

Depends on https://github.com/DeterminateSystems/nix-src/tree/tristanross/dsp-62-collab-figure-out-static-building-of-determinate-nix

Summary by CodeRabbit

• Refactor

  • Replace legacy global initialization with the standard library’s thread-safe lazy initialization, improving one-time initialization reliability and thread-safety.

• Chores

  • Remove the lazy_static dependency across modules.
  • Update the Nix flake input to point to a specific fork/branch.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Replaced lazy_static with std::sync::LazyLock across several nix-bindings crates, added a public init() in nix-bindings-fetchers, and updated flake.nix to point the nix input to a specific fork/branch. Store tests/fixtures adjusted for derivation JSON v4 structure.

Changes

Cohort / File(s)	Summary
Manifest removals \nix-bindings-expr/Cargo.toml`, `nix-bindings-flake/Cargo.toml`, `nix-bindings-store/Cargo.toml``	Removed lazy_static = "1.4" dependency from three crate manifests.
Fetchers init & LazyLock migration \nix-bindings-fetchers/src/lib.rs``	Added a static INIT: LazyLock<Result<()>>, new public pub fn init() -> Result<()>, and ensured init() is invoked in FetchersSettings::new().
Store LazyLock migration & cache init \nix-bindings-store/src/store.rs``	Replaced lazy_static statics with LazyLock-backed INIT and STORE_CACHE (closures initialize libstore_init and cache); preserved APIs and cache semantics.
Expr LazyLock migration \nix-bindings-expr/src/eval_state.rs``	Replaced lazy_static initialization with LazyLock<Result<()>>; moved init logic into LazyLock::new and adjusted imports.
Flake input update \flake.nix``	Updated nix input URL to github:DeterminateSystems/nix-src/...tristanross/dsp-62-collab-figure-out-static-building-of-determinate-nix.
Store tests/fixture schema update \nix-bindings-store/src/store.rs` (tests/fixtures)`	Updated derivation JSON schema from v3 to v4 (inputDrvs/inputSrcs → inputs.{drvs,srcs}).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Set up bindings for use with Determinate Nix #1 — also modifies flake.nix to point the nix input to a DeterminateSystems fork/branch.

Suggested reviewers

• cole-h

Poem

🐰 I swapped the statics, soft and quick,
LazyLock now keeps the init slick.
A gentle init() hops into place,
Flake points to a branch with happy grace. 🥕

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Add init function for fetchers' directly aligns with the main change: introducing a new public init() function in nix-bindings-fetchers/src/lib.rs. While the PR also includes refactoring from lazy_static to LazyLock across multiple files, the primary objective is adding the fetchers initialization function.

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✨ Finishing touches

• 📝 Generate docstrings

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[coderabbitai]

Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

nix-bindings-store/src/store.rs (1)

674-687: Update version gate to 2.33 for v4 JSON test fixtures.
Derivation JSON v4 with the new inputs: { srcs, drvs } shape was introduced in Nix 2.33.0. The current #[cfg(nix_at_least = "2.31")] gating is too permissive—tests emitting v4 JSON will fail on Nix 2.31 and 2.32, which only support v3 (with top-level inputSrcs/inputDrvs). Change the cfg gate to nix_at_least = "2.33" for all v4 JSON fixtures at lines 674-687, 759-783, 837-850, 893-906, 949-962, or provide separate v3-format fixtures for 2.31/2.32 compatibility.

🧹 Nitpick comments (1)

nix-bindings-fetchers/src/lib.rs (1)

37-45: Initialization call is correctly placed.

Calling init()? at the start of new() ensures libfetchers is initialized before settings creation.

Minor style inconsistency: Line 10 uses check_call! (via direct import), while line 41 uses context::check_call!. Consider using consistent macro invocation throughout the file.

♻️ Optional: Consistent macro usage

-        let ptr = unsafe { context::check_call!(raw::fetchers_settings_new(&mut ctx))? };
+        let ptr = unsafe { check_call!(raw::fetchers_settings_new(&mut ctx))? };

[cole-h]

Does this PR depend on this branch, or were you just playing with it?

[RossComputerGuy]

Depends on it for the nix_libfetchers_init function.