Can't resolve C warning in STM32CubeIDE-CodePudding

Facing a a warning which I am not able to get rid of. I am using stm32 MCU and STM32CubeIDE with a standard C11 compiler. Array gpioOutPins is used by in a function call gpio.c file. This function which contains this function call is called from inOut.c file. Please note that the inOut.c file is in User Application layer while the gpio.c file is in the Kernel (Core) section of the project tree as can be seen below. I was not able to accommodate the whole project tree in the snapshot.

I don't understand why this warning is generated. Any help is appreciated. Thank you.

An array is deifned in a header file gpio.h:

static uint16_t gpioOutPins[GPIO_OUT_CH_NR] =
{
    DOUT_OD_OUT4_Pin, 
    DOUT_OD_OUT6_Pin, 
    DOUT_OD_OUT5_Pin, 
    DOUT_OD_OUT7_Pin, 
    DOUT_LED_DISABLE_Pin, 
    DOUT_BUZZ_Pin, 
    DOUT_OD_OUT8_Pin, 
    DOUT_OD_OUT3_Pin, 
    DOUT_OD_OUT2_Pin, 
    DOUT_OD_OUT1_Pin, 
    DOUT_ALARM_Pin, 
    DOUT_12V_PWR_Pin, 
    DOUT_12V_PWR_Pin
};

The directory structure looks like this:

The warning generated by the compiler is this:

warning: 'gpioOutPins' defined but not used [-Wunused-variable]

CodePudding user response：

Header (.h) files are not a good place to define global variables, because when they are included in source (.c) files, multiple independent copies of them come to existence. They share the same name, but they are actually different variables. And if they are not static, the linker rejects them because of multiple definitions.

Your inOutTask.c probably includes gpio.h header directly or indirectly, so another copy of gpioOutPins comes into existence, which is distinct from the one used in gpio.c. Because you don't use gpioOutPins in inOutTask.c, you get the warning.

The proper way is to move the definition into gpio.c, remove the static keyword, and add extern uint16_t gpioOutPins[GPIO_OUT_CH_NR]; to gpio.h