Comment by aw1621107

That paper isn't relevant here. From the paper (emphasis added):

> 7.1.3 Reserved Identifiers

> [snip]

> Macro names and identifiers with external linkage that are specified in the C standard library clauses.

> This proposal does not propose any changes to these reserved identifiers.

Furthermore, that paper doesn't make the use of reserved external identifiers not UB, so there's no change there either.