cmake: enable libunwind_mac only for inproc

[zhaowq32]

Summary

Restrict SENTRY_WITH_LIBUNWIND_MAC to the inproc backend on Apple platforms.

Motivation

libunwind_mac is only needed for Sentry's local unwinding path used by the inproc backend. When building with breakpad on Apple targets, this file is still compiled today because the CMake condition enables it for all APPLE builds.

That creates unnecessary build exposure for Apple configurations that do not use this unwinder at runtime, including older iOS SDK / armv7 setups where libunwind_mac can fail to compile.

Changes

• Update the top-level CMake unwinder selection logic so SENTRY_WITH_LIBUNWIND_MAC is enabled only when:
  • the target platform is APPLE
  • and SENTRY_BACKEND_INPROC is selected

Impact

• macOS/iOS + breakpad: no longer compile sentry_unwinder_libunwind_mac.c
• macOS/iOS + inproc: behavior unchanged
• No functional changes to the Breakpad crash handling path

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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No unwinder on Apple with non-inproc backends

High Severity

On Apple platforms with non-inproc backends (e.g., macOS defaults to crashpad), no unwinder is compiled in. The public APIs sentry_value_new_stacktrace, sentry_value_set_stacktrace, and sentry_event_value_add_stacktrace all rely on sentry_unwind_stack via unwind_stack(), which now returns 0 on these configurations because no SENTRY_WITH_UNWINDER_* macro is defined. This silently produces empty stack traces when users pass ips == NULL.

Additional Locations (1)

• CMakeLists.txt#L239-L241

 

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