nix: restore atf cross overlay dropped in #3810

[insipx]

Summary

The 2026-07-03 nightly failed in release-node-sdk / bindings / build-macos (darwin-arm64):

atf-aarch64-apple-darwin> configure: error: cannot run test program while cross compiling
error: Cannot build '...libiconv-aarch64-apple-darwin-113.drv' — 1 dependency failed
error: Cannot build '...bindings-node-js-napi-aarch64-apple-darwin-1.11.0-dev.drv'

No node-sdk/node-bindings npm nightly has published since 20260630.ac662b3 — and because the nightly watermark is the latest tag of any SDK, the successful iOS leg's 20260703 tag makes every subsequent scheduled run log "No new commits since last nightly; skipping", so the node leg never retried.

Why the upstream fix doesn't cover this

#3810 removed this overlay expecting NixOS/nixpkgs#510292 (merged, present in the pinned nixos-unstable rev b5aa0fbd) to cover it. The upstream seeds are gated on !stdenv.buildPlatform.canExecute stdenv.hostPlatform — but this build's cross is aarch64-darwin → aarch64-apple-darwin: same arch, same kernel, so canExecute is true and the seeds never apply, while autoconf still decides cross_compiling=yes from the configured-triple mismatch and aborts the AC_RUN_IFELSE probes.

This restores the original overlay verbatim (structurally gated on buildPlatform != hostPlatform) with the comment updated to record the upstream state and the retirement condition: the upstream gate switching to structural inequality (nixpkgs follow-up incoming). Double-applying the seeds when both gates fire is harmless — same cache values.

Verification: nix-instantiate --parse clean; the real proof is the next scheduled nightly (new commit un-skips the watermark) or a manual Release dispatch with node-sdk: true.

🤖 Generated with Claude Code

Note

Restore atf cross-compilation overlay in nix patches

Restores an overlay in patches.nix that was dropped in #3810. When buildPlatform != hostPlatform, the atf derivation is overridden to pre-seed three autoconf cache variables (kyua_cv_getopt_plus, kyua_cv_attribute_noreturn, kyua_cv_getcwd_works) so AC_RUN_IFELSE tests are skipped and configuration succeeds during cross-compilation.

^{Macroscope summarized f4005df.}

[claude]

Claude finished @insipx's task —— View job

---

Code Review — 2026-07-06 16:03 UTC

Summary

The implementation is correct and well-justified. This is a pragmatic workaround for a gap in the upstream nixpkgs fix where structural cross-compilation detection (buildPlatform != hostPlatform) differs from runtime capability detection (canExecute).

Positive Observations

1. Excellent documentation (lines 11-46): The comment thoroughly explains:

   • The root cause (AC_RUN_IFELSE probes in atf 0.23)
   • Why the upstream fix doesn't apply (canExecute gate mismatch)
   • Justification for each cache variable with platform research
   • Retirement condition (upstream switching to structural inequality)

2. Correct gate condition (line 51): Using buildPlatform != hostPlatform is the appropriate structural check that catches the aarch64-darwin → aarch64-apple-darwin case.

3. Safe implementation:

   • Properly preserves existing configureFlags with old.configureFlags or []
   • Cache variable seeding is idempotent (double-application is harmless as noted)
   • Gated to cross-builds only (preserves cache.nixos.org substitution for native)

4. Low risk: The three cache variables are conservatively seeded based on well-researched platform behavior that holds across Darwin, glibc, and musl.

No Issues Found

• Code quality: ✓ Idiomatic Nix, follows patterns from other overlays in the file
• Bugs: None identified
• Performance: ✓ Conditional application minimizes impact
• Security: ✓ No security implications (configuration flags only)
• Test coverage: Manual verification via nightly builds is appropriate for Nix overlays

Recommendation

Approve. This is a necessary bridge until nixpkgs switches to structural inequality. The implementation is sound and well-documented.

---

Tasks Completed

• Read changed file nix/lib/patches.nix
• Analyze the overlay implementation
• Review code quality and best practices
• Check for potential bugs or issues
• Post review feedback

---

[macroscopeapp]

Approvability

Verdict: Approved

Restores a Nix cross-compilation overlay for the atf package that was accidentally dropped in #3810. This is a build configuration fix with no runtime impact, well-documented rationale, and the author owns the affected file.

^{You can customize Macroscope's approvability policy. Learn more.}