[libc++] Annotate {set,get}_terminate to return non-null pointers

[philnik777]

No description provided.

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Nikolas Klauser (philnik777)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/169492.diff

1 Files Affected:

• (modified) libcxx/include/__exception/operations.h (+2-2)

diff --git a/libcxx/include/__exception/operations.h b/libcxx/include/__exception/operations.h
index 29d5c698a96db..d3021782e8660 100644
--- a/libcxx/include/__exception/operations.h
+++ b/libcxx/include/__exception/operations.h
@@ -25,8 +25,8 @@ _LIBCPP_EXPORTED_FROM_ABI unexpected_handler get_unexpected() _NOEXCEPT;
 #endif
 
 using terminate_handler = void (*)();
-_LIBCPP_EXPORTED_FROM_ABI terminate_handler set_terminate(terminate_handler) _NOEXCEPT;
-_LIBCPP_EXPORTED_FROM_ABI terminate_handler get_terminate() _NOEXCEPT;
+[[__gnu__::__returns_nonnull__]] _LIBCPP_EXPORTED_FROM_ABI terminate_handler set_terminate(terminate_handler) _NOEXCEPT;
+[[__gnu__::__returns_nonnull__]] _LIBCPP_EXPORTED_FROM_ABI terminate_handler get_terminate() _NOEXCEPT;
 
 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_UNCAUGHT_EXCEPTION)
 _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 bool uncaught_exception() _NOEXCEPT;

[ldionne]

Since the standard actually allows us to return null, I wouldn't bake this into the declaration: https://en.cppreference.com/w/cpp/error/set_terminate.html

Since the benefit is likely small anyway, I would suggest not moving forward with this patch.