[Bug preprocessor/96935] [9/10/11 Regression] ICE in subspan, at input.h:69

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96935

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r269125.  Use -O to reproduce.

Bizarrely, it goes away when -Wall is in effect!