enhance error codec and exit code (#6602)

youknowone · web-flow · commit 00ae4a175136 · 2025-12-31T11:28:04.000+09:00
diff --git a/crates/vm/src/vm/mod.rs b/crates/vm/src/vm/mod.rs
@@ -327,11 +327,17 @@ impl VirtualMachine {
                     let line_buffering = buffered_stdio && (isatty || fd == 2);
 
                     let newline = if cfg!(windows) { None } else { Some("\n") };
+                    // stderr uses backslashreplace error handler
+                    let errors: Option<&str> = if fd == 2 {
+                        Some("backslashreplace")
+                    } else {
+                        None
+                    };
 
                     let stdio = self.call_method(
                         &io,
                         "TextIOWrapper",
-                        (buf, (), (), newline, line_buffering, write_through),
+                        (buf, (), errors, newline, line_buffering, write_through),
                     )?;
                     let mode = if write { "w" } else { "r" };
                     stdio.set_attr("mode", self.ctx.new_str(mode), self)?;
@@ -853,7 +859,13 @@ impl VirtualMachine {
                 [arg] => match_class!(match arg {
                     ref i @ PyInt => {
                         use num_traits::cast::ToPrimitive;
-                        return i.as_bigint().to_u32().unwrap_or(0);
+                        // Try u32 first, then i32 (for negative values), else -1 for overflow
+                        let code = i
+                            .as_bigint()
+                            .to_u32()
+                            .or_else(|| i.as_bigint().to_i32().map(|v| v as u32))
+                            .unwrap_or(-1i32 as u32);
+                        return code;
                     }
                     arg => {
                         if self.is_none(arg) {
@@ -866,8 +878,11 @@ impl VirtualMachine {
                 _ => args.as_object().repr(self).ok(),
             };
             if let Some(msg) = msg {
-                let stderr = stdlib::sys::PyStderr(self);
-                writeln!(stderr, "{msg}");
+                // Write using Python's write() to use stderr's error handler (backslashreplace)
+                if let Ok(stderr) = stdlib::sys::get_stderr(self) {
+                    let _ = self.call_method(&stderr, "write", (msg,));
+                    let _ = self.call_method(&stderr, "write", ("\n",));
+                }
             }
             1
         } else if exc.fast_isinstance(self.ctx.exceptions.keyboard_interrupt) {
