[libcxx-commits] [libcxx] [libc++] Introduce a new attribute keyword for Clang improves compatibility with Mingw-GCC (PR #141040)

[via libcxx-commits]

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@@ -530,6 +530,48 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_HIDE_FROM_ABI_AFTER_V1 _LIBCPP_HIDE_FROM_ABI
 #  endif
 
+// _LIBCPP_HIDE_FROM_ABI is required for member functions defined within an inner class of a class template
+// (e.g., std::basic_ostream<...>::sentry::sentry(...)), due to inconsistent behavior in MinGW-GCC (and
+// Cygwin as well, in all relevant cases) regarding template instantiation and symbol visibility when combined
+// with __declspec(dllexport/dllimport).
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jeremyd2019 wrote:

```suggestion
// with __declspec(dllexport/dllimport) and extern.
```

https://github.com/llvm/llvm-project/pull/141040