APB12 is never defined as a macro. It is an element in the bus_t enum.
Therefore, the test to check if it is defined will always fail.
APB12 is not a real bus. It is the second register of the APB1 bus. I am
not aware of any STM32 family where the ABP2 bus is implmented (ie
RCC_APB2ENR_SYSCFGEN is defined) and devices attached to said bus are
enabled via the APB1 second register. For this reason, the fix is to
simply remove the check.
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