In Terraform, how do I define a ValidateFunc on an attribute that uses *schema.ResourceData (to validate one attribute based on values of others)?

Question

I am building a Terraform Project that uses the old Terraform Plugin SDK v2 (not the new Plugin Framework). Recently, I've defined a validation function on an attribute in a resource:

"custom_attribute": {
    Type:         schema.TypeString,
    Required:     true,
    Description:  "Some Description",
    ValidateFunc: validateCustomAttributeValue,
},

func validateCustomAttributeValue(val interface{}, key string) (warns []string, errs []error) {
    customAttributeValue := val.(string)

    // listValidCustomAttributeValues() returns a list of valid values of "custom_attribute"
    listOfValidCustomAttributeValues := listValidCustomAttributeValues()

    isValidCustomAttributeValue := slices.Contains(listOfValidCustomAttributeValues, customAttributeValue)
    if !isValidCustomAttributeValue {
        errs = append(errs, fmt.Errorf("some custom error"))
    }

    if customAttributeValue == "SPECIFIC_VALUE" {
        warns = append(warns, `some custom warning`)
    }
    return warns, errs
}

I would like to write a similar function for a different attribute (say X), but in the ValidateFunc of X, I would like the ability to check the values of other attributes in the resource and based on those values, return errors/warnings (basically, validate the value of X based on values of other attributes in the resource).

To do this, the signature of the ValidateFunc I've used in the example above does not allow me to use d *schema.ResourceData as an argument, and any workaround I try in this regard does not work; but I am badly in need of using d *schema.ResourceData somewhere in the ValidateFunc.

May I get some ideas on how I can get this working?