Checking unstable options from toml files

Author: Tarin Mahmood

src/config.rs

@@ -263,15 +263,7 @@ macro_rules! create_config {
         impl<'a> ConfigSetter<'a> {
             $(
             pub fn $i(&mut self, value: $ty) {
-                // we check if we are using nightly channel
-                let unstable = is_nightly_channel!();
-                if !(self.0).$i.3 {
-                    (self.0).$i.2 = value;
-                } else {
-                    if unstable {
-                        (self.0).$i.2 = value;
-                    }
-                }
+                (self.0).$i.2 = value;
             }
             )+
         }
@@ -308,8 +300,18 @@ macro_rules! create_config {
             fn fill_from_parsed_config(mut self, parsed: PartialConfig) -> Config {
             $(
                 if let Some(val) = parsed.$i {
-                    self.$i.1 = true;
-                    self.$i.2 = val;
+                    if !self.$i.3 {
+                        self.$i.1 = true;
+                        self.$i.2 = val;
+                    } else {
+                        if is_nightly_channel!() {
+                            self.$i.1 = true;
+                            self.$i.2 = val;
+                        } else {
+                            println!("Warning: can't set some features as unstable \
+                                    features are only available in nightly channel.");
+                        }
+                    }
                 }
             )+
                 self
@@ -707,4 +709,17 @@ mod test {
         assert_eq!(config.unstable_features(), true);
         ::std::env::set_var("CFG_RELEASE_CHANNEL", v);
     }
+
+    #[test]
+    fn test_unstable_from_toml() {
+        let mut config = Config::from_toml("unstable_features = true").unwrap();
+        assert_eq!(config.was_set().unstable_features(), false);
+        let v = ::std::env::var("CFG_RELEASE_CHANNEL").unwrap_or(String::from(""));
+        ::std::env::set_var("CFG_RELEASE_CHANNEL", "nightly");
+        config = Config::from_toml("unstable_features = true").unwrap();
+        assert_eq!(config.was_set().unstable_features(), true);
+        assert_eq!(config.unstable_features(), true);
+        ::std::env::set_var("CFG_RELEASE_CHANNEL", v);
+    }
+
 }