[libc++] Simplify the __libcpp_refstring implementation

[philnik777]

We don't support any platforms anymore where the __libcpp_refstring has to be ABI compatible with libstdc++'s C++03 implementation of string, so we can significantly simplify the implementation.

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff origin/main HEAD --extensions ,h -- libcxx/include/stdexcept libcxx/src/include/refstring.h --diff_from_common_commit

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View the diff from clang-format here.

diff --git a/libcxx/src/include/refstring.h b/libcxx/src/include/refstring.h
index 3c7c5cc5b..acc11b25e 100644
--- a/libcxx/src/include/refstring.h
+++ b/libcxx/src/include/refstring.h
@@ -27,7 +27,7 @@ struct __libcpp_refstring::__rep {
 inline __libcpp_refstring::__libcpp_refstring(const char* msg) {
   std::size_t len = strlen(msg);
   auto* rep       = static_cast<__rep*>(::operator new(sizeof(__rep) + len + 1));
-  rep->refcount      = 0;
+  rep->refcount   = 0;
   std::memcpy(rep->data, msg, len + 1);
   __imp_ = rep;
 }

[ldionne]

On macOS, we don't support building new code against libstdc++ anymore. However, for backwards compatibility with apps that have already been built a long time ago, we do provide libstdc++.dylib in the dyld shared cache.

I aslo did a search and I did find some applications available for download on the App Store which reference some symbols from libstdc++. Hence, I think we need to keep this old code, sadly 🙁