[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #1 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Created attachment 55452
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55452&action=edit
bug.cpp.orig.xz

In case I reduced the file incorrectly attaching bug.cpp.orig.xz which should
build with both gcc-13 and gcc-14.