build: generate src/version.rs without hbb_common

[luminoso]

build.rs calls hbb_common::gen_version(), which makes hbb_common a build dependency. Cargo then compiles the whole crate for the build host, including libsodium-sys. When cross compiling with pkg-config pointed at the target sysroot, the host build script links the target libsodium and fails:

rust-lld: error: .../aarch64_generic_musl/usr/lib/libsodium.so is incompatible with elf64-x86-64
error: could not compile `hbbs` (build script)

This happens on every non-x86_64 target when packaging hbbs and hbbr for OpenWrt (openwrt/packages#30572), and only passes on x86_64 because host and target share the machine type.

The change writes src/version.rs from CARGO_PKG_VERSION with the standard library, so the build script has no dependencies at all. VERSION is unchanged. BUILD_DATE stays as an empty constant: nothing in hbbs or hbbr reads it, and a constant value makes the build reproducible. Cargo.lock does not change because hbb_common remains a normal dependency.

Tested by building 1.1.16 with this change applied for x86_64 musl in the OpenWrt SDK; hbbs --version prints hbbs 1.1.16 and the build script binary no longer links libsodium.

Summary by CodeRabbit

• Chores
  • Streamlined application version handling during builds.
  • Improved consistency by regenerating version information whenever project metadata changes.
  • Removed an unnecessary build-time dependency.
  • No user-facing functionality or behavior changes are included in this update.

Confidence Score: 5/5

The PR appears safe to merge and cleanly removes the problematic host dependency without changing consumed version behavior.

Summary

This PR removes hbb_common from the host-side build dependency graph and replaces its version-file generator with a standard-library-only build script.

• Generates VERSION from Cargo’s package version.
• Preserves the unused BUILD_DATE constant as an empty reproducible value.
• Avoids compiling and linking target-oriented native dependencies for the build host during cross-compilation.

_{Reviews (1) · Last reviewed commit: "build: generate src/version.rs without h..."}

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 27999cdf-b4f3-4409-bed2-f1af525d089f

📥 Commits

Reviewing files that changed from the base of the PR and between a7736be and 071796a.

📒 Files selected for processing (2)

• Cargo.toml
• build.rs

💤 Files with no reviewable changes (1)

• Cargo.toml

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📝 Walkthrough

Walkthrough

The build no longer depends on hbb_common. build.rs now generates src/version.rs from CARGO_PKG_VERSION and reruns when Cargo.toml changes.

Changes

Version generation

Layer / File(s)	Summary
Build-time version generation Cargo.toml, build.rs	The hbb_common build dependency was removed. build.rs now writes public VERSION and empty BUILD_DATE constants to src/version.rs, and Cargo reruns it when Cargo.toml changes.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 07179

This change preserves generated version behavior while removing the build-only dependency affecting cross-compilation, so it is ready to merge with normal checks.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: generating src/version.rs in build.rs without the hbb_common build dependency.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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🧪 Generate unit tests (beta)

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