I'm pretty sure we're dealing with a compiler regression here: note that there isn't actually any usage of bitfields in the test case given (rather, it uses a volatile int), it just so happened that the code to implement -fstrict-volatile-bitfields caused a particular code path to be erroneously executed.
If things are working properly, the compilability of the code shouldn't be affected by the -f[no-]strict-volatile-bitfields options.
I'm pretty sure we're dealing with a compiler regression here: note that there isn't actually any usage of bitfields in the test case given (rather, it uses a volatile int), it just so happened that the code to implement -fstrict- volatile- bitfields caused a particular code path to be erroneously executed.
If things are working properly, the compilability of the code shouldn't be affected by the -f[no-] strict- volatile- bitfields options.