fix: link macOS CoreServices for the bundled notify/FSEvents backend

[kixelated]

Summary

The Go bindings (github.com/moq-dev/moq-go) and any C/CMake consumer of libmoq failed to link on macOS with undefined _FSEventStream* / _FSEvents* symbols:

Undefined symbols for architecture arm64:
  "_FSEventStreamCreate", referenced from:
      notify::fsevent::FsEventWatcher::run ... in libmoq_ffi.a
  ...
ld: symbol(s) not found for architecture arm64

Root cause: moq-native's default features enable quinn, which implies the watch feature and pulls in notify. Both moq-ffi and libmoq link moq-native with default features, so libmoq_ffi.a and libmoq.a bundle notify's FSEvents backend. Those symbols live in the macOS CoreServices framework, which the Go cgo flags and the libmoq CMake config did not link. Only build.rs's pkg-config already listed it (rs/libmoq/build.rs:33), so the three link configs were inconsistent. Linux uses inotify and needs no extra framework, which is why the Linux-only CI never caught it.

Changes

• go/moq/cgo.go: add -framework CoreServices to both darwin,amd64 and darwin,arm64 LDFLAGS.
• rs/libmoq/CMakeLists.txt + rs/libmoq/cmake/moq-config.cmake.in: add CoreServices, bringing the CMake / find_package(moq) path in line with build.rs. Confirmed libmoq.a carries the same undefined FSEvents symbols.
• go/moq/link_test.go: a link smoke test. go build ./... compiles the cgo library but never links a binary, so a missing framework slips through compilation; go test ./... (already run by go/scripts/check.sh) now links a real test binary and surfaces it.

Test plan

• nm confirms libmoq_ffi.a and libmoq.a both carry the 9 undefined _FSEvent* symbols.
• On darwin/arm64, a consumer binary fails to link without the framework (exact bug-report error) and links + runs with it.
• just go check green; the new link_test.go is staged and go test ./... passes. A/B confirmed the test fails the build without CoreServices and passes with it.
• Swift checked (just swift check): unaffected, links and tests pass without declaring the framework (Apple-toolchain autolink). Kotlin/Python load the dynamic lib (rustc links it self-contained), so they are unaffected.

Targets main: a build/link fix, with no public API or wire-protocol change.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 6254567f-8ece-4651-918d-15bae278e5fc

📥 Commits

Reviewing files that changed from the base of the PR and between 96203f3 and 87ddf72.

📒 Files selected for processing (4)

• go/moq/cgo.go
• go/moq/link_test.go
• rs/libmoq/CMakeLists.txt
• rs/libmoq/cmake/moq-config.cmake.in

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Walkthrough

The macOS linker configuration for the moq package is extended to include the CoreServices Apple framework. This change is applied in three places: the Go cgo LDFLAGS directives for both darwin/amd64 and darwin/arm64 in go/moq/cgo.go, the CMake target_link_options for the moq interface target in rs/libmoq/CMakeLists.txt, and the INTERFACE_LINK_LIBRARIES for the moq::moq imported target in rs/libmoq/cmake/moq-config.cmake.in. A new empty TestLink test function is added in go/moq/link_test.go to exercise link-time resolution of cgo/FFI symbols during go test.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: adding CoreServices framework linking for macOS to fix FSEvents linking issues in the bundled notify backend.
Description check	✅ Passed	The description is comprehensive and directly related to the changeset, explaining the root cause, changes made, and testing performed for the CoreServices framework linking fix.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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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✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/clever-dirac-ca63da

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

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