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cgccc99suppress-warnings

How to eliminate the "discard qualifier" warning?

Using GCC and C99 mode, I have a function declared as:

void func(float *X);

When I call the function, I use a volatile array Y:

volatile float Y[2];
int main()
{
    func(Y);
    return 0;
}

When compiling (with -Wall), I get the following warning:

warning: passing argument 1 of ‘func’ discards qualifiers from pointer target type
blah.c:4: note: expected ‘float *’ but argument is of type ‘volatile float *’

I can eliminate it with an explicit (float *) type cast, but this repeats in many places in the code.

Is there a way to eliminate this specific warning, with an option or a pragma (or something equivalent)?

Solution

  • No, you can't turn that warning off. It's telling you you're violating the type system. If you want to call func you either need to pass it pointers to non-volatile data or change the function signature to accept pointers to volatile data.