The C++ Standard doesn't mention the word 'mangle', however it is at
least on some level aware of mangling because you can write "extern C"
to tell the compiler not to mangle a name -- or at least to mangle it
the way it would get mangled if it were C instead of C++.
I'm not sure I agree with that. The standard only says that "extern C" provides for linkage to the C programming language. Although implementations typically use mangling for this, the standard doesn't say anything about it. So you're not only proposing another way to specify mangling, you're proposing introducing knowledge of mangling at all to the standard, which is quite a big change imo.
Cheers,
Anders