Feature::from_str is not always needed

library/stdarch/crates/std_detect/src/detect/macros.rs

@@ -69,6 +69,7 @@ macro_rules! features {
                     Feature::_last => unreachable!(),
                 }
             }
+            #[cfg(feature = "std_detect_env_override")]
             pub(crate) fn from_str(s: &str) -> Result<Feature, ()> {
                 match s {
                     $($feature_lit => Ok(Feature::$feature),)*