Unable to handle assignment to a bitfield when optimizations are enabled and the struct has not been initialized

[dibyendumajumdar]

Example code that fails when -O1 option is enabled:

https://github.com/dibyendumajumdar/dmr_c/blob/master/tests/set1/onebit.c

For a discussion of this issue see:

http://marc.info/?l=linux-sparse&m=149074012006676&w=3

Workaround is to disable optimizations by not supplying -O1.