bison produces an output which causes gcc to hang

[todd freed]

Hello,

I have found a bug in the gcc preprocessor which causes gcc to hang.
The smallest input to gcc which causes this hang is,

#line 1 "/dev/stdout"
#def xy

The bug report to gcc is here,
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90034

bison will produce such an output when invoked like,

bison -o /dev/stdout parser.y

I hesitate to even file a bug report with bison, except that it seems
to be a regression. That is, recent version(s) of bison produce such
an output, but I have used bison in this fashion for years without a
problem. I believe this is a recent behavior change in bison.

I tried to build bison from historical tags (v3.0 and v3.2) to check
the previous behavior, but was not able to produce a binary that
worked on my system.

Thanks

-Todd