Fedora 18 Beta was mounting tmpfs on /tmp to, hopefully, reduce disk I/O and extend the life of SSD disks.
Since tmpfs was very limited in size, cscope ran out of space while indexing larger source tree.
I had to use:
TMPDIR=/var/tmp cscope -b -q -k
to enable cscope to complete its indexing.
I think cscope should consider storing temp files in /var/tmp.
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