Add sys.warn_default_encoding

src/lib.rs

@@ -386,6 +386,7 @@ fn create_settings(matches: &ArgMatches) -> Settings {
     }
 
     let mut dev_mode = false;
+    let mut warn_default_encoding = false;
     if let Some(xopts) = matches.values_of("implementation-option") {
         settings.xopts.extend(xopts.map(|s| {
             let mut parts = s.splitn(2, '=');
@@ -393,11 +394,19 @@ fn create_settings(matches: &ArgMatches) -> Settings {
             if name == "dev" {
                 dev_mode = true
             }
+            if name == "warn_default_encoding" {
+                warn_default_encoding = true
+            }
             let value = parts.next().map(ToOwned::to_owned);
             (name, value)
         }));
     }
     settings.dev_mode = dev_mode;
+    if warn_default_encoding
+        || (!ignore_environment && env::var_os("PYTHONWARNDEFAULTENCODING").is_some())
+    {
+        settings.warn_default_encoding = true;
+    }
 
     if dev_mode {
         settings.warnopts.push("default".to_owned())

vm/src/stdlib/sys.rs

@@ -603,6 +603,8 @@ mod sys {
         dev_mode: bool,
         /// -X utf8
         utf8_mode: u8,
+        /// -X warn_default_encoding, PYTHONWARNDEFAULTENCODING
+        warn_default_encoding: u8,
     }
 
     #[pyimpl(with(PyStructSequence))]
@@ -624,6 +626,7 @@ mod sys {
                 isolated: settings.isolated as u8,
                 dev_mode: settings.dev_mode,
                 utf8_mode: 1,
+                warn_default_encoding: settings.warn_default_encoding as u8,
             }
         }
 

vm/src/vm/setting.rs

@@ -43,6 +43,9 @@ pub struct Settings {
     /// -Xdev
     pub dev_mode: bool,
 
+    /// -X warn_default_encoding, PYTHONWARNDEFAULTENCODING
+    pub warn_default_encoding: bool,
+
     /// -Wfoo
     pub warnopts: Vec<String>,
 
@@ -78,6 +81,7 @@ impl Default for Settings {
             xopts: vec![],
             isolated: false,
             dev_mode: false,
+            warn_default_encoding: false,
             warnopts: vec![],
             path_list: vec![
                 #[cfg(all(feature = "pylib", not(feature = "freeze-stdlib")))]