[libcxx-commits] [PATCH] D65667: [libcxx] Avoid destructor call for error_category singletons

[Arthur O'Dwyer via Phabricator via libcxx-commits]

Quuxplusone added inline comments.


================
Comment at: libcxx/src/system_error.cpp:232-238
 const error_category&
 system_category() _NOEXCEPT
 {
-    static __system_error_category s;
-    return s;
+    _LIBCPP_SAFE_STATIC_AFTER_CXX11
+    static SystemErrorHelper s;
+    return s.system_error_category.new_system_error_category;
 }
----------------
After rebasing, I would expect this would end up looking like
```
const error_category&
system_category() _NOEXCEPT
{
    union U {
        __system_error_category s;
        _LIBCPP_CONSTEXPR explicit U() : s() {}
        ~U() {}  // Too bad this can't be trivial... or can it?
    };
    static _LIBCPP_CONSTINIT U u;
    return u.s;
}
```
i.e. a very small diff against the left-hand side.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65667/new/

https://reviews.llvm.org/D65667