I found the following commit
(https://github.com/cplusplus/modules-ts/commit/d2b044dd3f14af1fb926861a2f773e56fb439cc0)
which introduced the pp-decl-suffix nonterminal, replacing pp-attrs.
Maybe the remaining tokens should be used for attributes.

On Sat, Aug 24, 2019 at 12:12 AM Maris Razvan <razvyboy2004_at_[hidden]> wrote:
>
> Hello,
>
> In the current C++ draft (august 2019), the grammar for a pp-import
> (http://eel.is/c++draft/cpp.import#nt:pp-import) allows for additional
> pp-tokens after the header-name or the header-name-tokens.
>
> The current version of that section is the result of P1703:
> "Recognizing Header Unit Imports Requires Full Preprocessing"
> (http://open-std.org/JTC1/SC22/WG21/docs/papers/2019/p1703r1.html).
> Before the changes caused by this proposal, the grammar still allowed
> for preprocessing tokens tokens after the header-name or the
> header-name-tokens, but in the form of a pp-import-suffix. (section
> [cpp.module] of P1103
> (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1103r3.pdf)).
>
> What is the reasoning behind allowing additional, unused preprocessing
> tokens in this context?
>
> Thank you.