Compiler warnings about -Wregister in STM32C0x

[maxgerhardt]

Describe the bug
Compiling for STM32C0x produces tons of register warnings in even the latest git commit version. They are all about the same

warning: ISO C++17 does not allow 'register' storage class specifier 

type.

For example from

Arduino_Core_STM32/system/Drivers/STM32C0xx_HAL_Driver/Inc/stm32c0xx_ll_adc.h

Lines 3671 to 3677 in 361a7fd

	__STATIC_INLINE void LL_ADC_SetAnalogWDMonitChannels(ADC_TypeDef *ADCx, uint32_t AWDy, uint32_t AWDChannelGroup)
	{
	/* Set bits with content of parameter "AWDChannelGroup" with bits position */
	/* in register and register position depending on parameter "AWDy". */
	/* Parameters "AWDChannelGroup" and "AWDy" are used with masks because */
	/* containing other bits reserved for other purpose. */
	register __IO uint32_t *preg;

arm-none-eabi-g++ -o .pio\build\genericSTM32C011F6\SrcWrapper\src\stm32\interrupt.cpp.o -c -std=gnu++17 -fno-threadsafe-statics -fno-rtti -fno-exceptions -fno-use-cxa-atexit -mcpu=cortex-m0plus -mthumb -Os -ffunction-sections -fdata-sections -nostdlib --param max-inline-insns-single=500 -DPLATFORMIO=60115 -DSTM32C0 -DSTM32C011xx -DARDUINO_GENERIC_C011F6PX -DSTM32C0xx -DARDUINO=10808 -DARDUINO_ARCH_STM32 -DNDEBUG -DARDUINO_GENERIC_C011F6PX -DBOARD_NAME=\"GENERIC_C011F6PX\" -DHAL_UART_MODULE_ENABLED -DUSE_HAL_DRIVER -DUSE_FULL_LL_DRIVER -DVARIANT_H=\"variant_generic.h\" -DVECT_TAB_OFFSET=0x0 [...]
In file included from C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_hal_adc.h:31,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\STM32C0xx/stm32c0xx_hal_conf_default.h:223,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\STM32C0xx/stm32c0xx_hal_conf.h:13,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_hal.h:30,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\CMSIS\Device\ST\STM32C0xx\Include/stm32c0xx.h:197,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\cores\arduino\stm32/stm32_def.h:24,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\cores\arduino\stm32/interrupt.h:43,
                 from C:\Users\Max\.platformio\packages\framework-arduinoststm32\libraries\SrcWrapper\src\stm32\interrupt.cpp:38:
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h: In function 'void LL_ADC_SetAnalogWDMonitChannels(ADC_TypeDef*, uint32_t, uint32_t)':
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h:3677:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
 3677 |   register __IO uint32_t *preg;
      |                           ^~~~
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h: In function 'uint32_t LL_ADC_GetAnalogWDMonitChannels(ADC_TypeDef*, uint32_t)':
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h:3781:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
 3781 |   register __IO uint32_t *preg = __ADC_PTR_REG_OFFSET(ADCx->CFGR1, ((AWDy & ADC_AWD_CRX_REGOFFSET_MASK) >> ADC_AWD_CRX_REGOFFSET_POS)
      |                           ^~~~
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h:3784:21: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
 3784 |   register uint32_t AnalogWDMonitChannels = (READ_BIT(*preg, AWDy) & AWDy & ADC_AWD_CR_ALL_CHANNEL_MASK);
      |                     ^~~~~~~~~~~~~~~~~~~~~
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h: In function 'void LL_ADC_ConfigAnalogWDThresholds(ADC_TypeDef*, uint32_t, uint32_t, uint32_t)':
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h:3903:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
 3903 |   register __IO uint32_t *preg = __ADC_PTR_REG_OFFSET(ADCx->AWD1TR, (((AWDy & ADC_AWD_TRX_REGOFFSET_MASK)) >> (ADC_AWD_TRX_REGOFFSET_BITOFFSET_POS)) + ((ADC_AWD_CR3_REGOFFSET & AWDy) >> (ADC_AWD_CRX_REGOFFSET_BITOFFSET_POS + 1UL)));
      |                           ^~~~
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h: In function 'void LL_ADC_SetAnalogWDThresholds(ADC_TypeDef*, uint32_t, uint32_t, uint32_t)':
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h:3980:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
 3980 |   register __IO uint32_t *preg = __ADC_PTR_REG_OFFSET(ADCx->AWD1TR, (((AWDy & ADC_AWD_TRX_REGOFFSET_MASK)) >> (ADC_AWD_TRX_REGOFFSET_BITOFFSET_POS)) + ((ADC_AWD_CR3_REGOFFSET & AWDy) >> (ADC_AWD_CRX_REGOFFSET_BITOFFSET_POS + 1UL)));
      |                           ^~~~
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h: In function 'uint32_t LL_ADC_GetAnalogWDThresholds(ADC_TypeDef*, uint32_t, uint32_t)':
C:\Users\Max\.platformio\packages\framework-arduinoststm32\system\Drivers\STM32C0xx_HAL_Driver\Inc/stm32c0xx_ll_adc.h:4022:33: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
 4022 |   register const __IO uint32_t *preg = __ADC_PTR_REG_OFFSET(ADCx->AWD1TR, (((AWDy & ADC_AWD_TRX_REGOFFSET_MASK)) >> (ADC_AWD_TRX_REGOFFSET_BITOFFSET_POS)) + ((ADC_AWD_CR3_REGOFFSET & AWDy) >> (ADC_AWD_CRX_REGOFFSET_BITOFFSET_POS + 1UL)));
      |                                 ^~~~

To Reproduce
Complete source code which can be used to reproduce the issue. Please try to be as generic as possible (no extra code, extra hardware,...)

Steps to reproduce the behavior:

1. Download https://github.com/maxgerhardt/pio-stm32c0
2. Open it in VSCode with the PlatformIO extension installed
3. Delete line 15 (extra_scripts = surpress_register_warnings.py)
4. Project Task -> Build
5. Observe errors

Expected behavior
Clean build, no warnings.

Screenshots
-/-

Desktop (please complete the following information):

• OS: Windows 10
• Arduino IDE version: Not applicable, PlatformIO core 6.1.15
• STM32 core version: Git hash 361a7fd
• Tools menu settings if not the default: Default
• Upload method: SWD

Board (please complete the following information):

• Name: Generic C011F6Px
• Hardware Revision: None
• Extra hardware used if any: None

Additional context
This was already raised in #2250 (comment) but closed and not fixed.

[fpistm]

Right this is linked to HAL/LL from the cube. This should be reported to STMICROELECTRONICS GitHub. Here we only use it no change. This will bre fixed within future update when fixed in the cube.

[fpistm]

You can file issue here to track progress:
https://github.com/STMicroelectronics/STM32CubeC0/issues

And here a list of issue already opened for other series:
https://github.com/search?q=org%3ASTMicroelectronics+%27register%27+storage+class+specifier+%5B-Wregister%5D&type=issues

[maxgerhardt]

The response I got from STMicroelectronics "support" is very "don't bother us" like.

Case#: 00208029
Subject: Using STM32C0xx HAL with C++ generates tons of warnings
Description:
Dear Mr. Max,

thank you for contacting ST support. register keyword in C "hints" compiler to store variable in core register, if possible. >Nevertheless, since ISO C++17 is usage of this keyword not supported and should not be used (however in C still OK). A simple solution may be removing the register keyword from the declarations.

With regards,
ST mcu support

[fpistm]

Unfortunately can do nothing here. Anyway I guess it will be removed as it is done for other series.