[Bug preprocessor/58844] [4.8 Regression] ICE with invalid use of ##

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58844

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Please see https://gcc.gnu.org/ml/gcc-patches/2009-04/msg01490.html for
reasoning why gcc considers it valid.