I am doing C++17 development on the STM32L4. The register storage class specifier has been deprecated for quite some time in C++ and is now forbidden. It seems to be used extensively in the STM32L4xx ADC LL interface. This causes quite a large number of warnings in any C++ code that includes the HAL header. This would not be a problem if the register usage was confined to C code. But it exists in macros defined in stm32l4xx_ll_adc.h which gets pulled in by any code that uses the HAL.
Is the use of the register keyword useful in these places? If it is not useful, it should be removed. If it is useful then I would prefer to see it confined to C source where it will be used. If it must remain in the header, please consider replacing it with a REGISTER macro that is only defined when __cplusplus is not defined.
These are the sort of warnings I am seeing with GCC:
Drivers/STM32L4xx_HAL_Driver/Inc/stm32l4xx_ll_adc.h:5210:21: warning: ISO C++1z does not allow 'register' storage class specifier [-Wregister]
register uint32_t AnalogWDMonitChannels = (READ_BIT(*preg, AWDy) & AWDy & ADC_AWD_CR_ALL_CHANNEL_MASK);
For now I am compiling with -Wno-register to avoid these warnings. But that seems less than ideal.
