Function xmlXPathCastStringToNumber 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn xmlXPathCastStringToNumber(
    val: *const xmlChar,
) -> f64

Cast a C string to a number per XPath 1.0 §4.2 conversion rules.

UPSTREAM-PARITY

double xmlXPathCastStringToNumber(const xmlChar *val);