Big update.

src/common/Utilities/advstd.h

@@ -24,6 +24,8 @@
 // this namespace holds implementations of upcoming stdlib features that our c++ version doesn't have yet
 namespace advstd
 {
+    // This workaround for std::remove_cvref_t, std::type_identify is needed for GCC 8...
+    // TODO: remove when we drop GCC 8 support. https://en.cppreference.com/w/cpp/compiler_support/20
     // C++20 advstd::remove_cvref_t
     template <class T>
     using remove_cvref_t = std::remove_cv_t<std::remove_reference_t<T>>;