Dereferencing type-punned pointer will break strict-aliasing rules

I used the following piece of code to read data from files as part of a larger program.

double data_read(FILE *stream,int code) {
        char data[8];
        switch(code) {
        case 0x08:
            return (unsigned char)fgetc(stream);
        case 0x09:
            return (signed char)fgetc(stream);
        case 0x0b:
            data[1] = fgetc(stream);
            data[0] = fgetc(stream);
            return *(short*)data;
        case 0x0c:
            for(int i=3;i>=0;i--)
                data[i] = fgetc(stream);
            return *(int*)data;
        case 0x0d:
            for(int i=3;i>=0;i--)
                data[i] = fgetc(stream);
            return *(float*)data;
        case 0x0e:
            for(int i=7;i>=0;i--)
                data[i] = fgetc(stream);
            return *(double*)data;
        }
        die("data read failed");
        return 1;
    }

Now I am told to use -O2 and I get following gcc warning: warning: dereferencing type-punned pointer will break strict-aliasing rules

Googleing I found two orthogonal answers:

• Concluding: there's no need to worry; gcc tries to be more law obedient than the actual law.

vs

• So basically if you have an int* and a float* they are not allowed to point to the same memory location. If your code does not respect this, then the compiler's optimizer will most likely break your code.

In the end I don't want to ignore the warnings. What would you recommend?

[update] I substituted the toy example with the real function.