From d8e582ef6eb19233d24aff86dca8872b972cafe4 Mon Sep 17 00:00:00 2001
From: "Jeong, YunWon" <69878+youknowone@users.noreply.github.com>
Date: Mon, 2 Feb 2026 02:02:12 +0900
Subject: [PATCH] _locale.localeconv (#6941)

---
 Lib/test/test__locale.py    |  2 --
 crates/stdlib/src/locale.rs | 40 +++++++++++++++++++++++++++++++++----
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/Lib/test/test__locale.py b/Lib/test/test__locale.py
index 054a6562f..11b2c9545 100644
--- a/Lib/test/test__locale.py
+++ b/Lib/test/test__locale.py
@@ -155,7 +155,6 @@ class _LocaleTests(unittest.TestCase):
         if not tested:
             self.skipTest('no suitable locales')
 
-    @unittest.skipIf(sys.platform in ('darwin', 'win32'), "TODO: RUSTPYTHON thread 'main' (18894384) panicked at crates/stdlib/src/locale.rs:106:14: localeconv always return decodable string: Utf8Error { valid_up_to: 0, error_len: Some(1) }")
     @unittest.skipIf(support.linked_to_musl(), "musl libc issue, bpo-46390")
     def test_lc_numeric_localeconv(self):
         # Test localeconv against known values
@@ -269,7 +268,6 @@ class _LocaleTests(unittest.TestCase):
         if not tested:
             self.skipTest('no suitable locales')
 
-    @unittest.skipIf(sys.platform in ('darwin', 'win32'), "TODO: RUSTPYTHON thread 'main' (18894384) panicked at crates/stdlib/src/locale.rs:106:14: localeconv always return decodable string: Utf8Error { valid_up_to: 0, error_len: Some(1) }")
     def test_float_parsing(self):
         # Bug #1391872: Test whether float parsing is okay on European
         # locales.
diff --git a/crates/stdlib/src/locale.rs b/crates/stdlib/src/locale.rs
index 98db77d0d..496325b50 100644
--- a/crates/stdlib/src/locale.rs
+++ b/crates/stdlib/src/locale.rs
@@ -101,10 +101,42 @@ mod _locale {
 
     unsafe fn pystr_from_raw_cstr(vm: &VirtualMachine, raw_ptr: *const libc::c_char) -> PyResult {
         let slice = unsafe { CStr::from_ptr(raw_ptr) };
-        let string = slice
-            .to_str()
-            .expect("localeconv always return decodable string");
-        Ok(vm.new_pyobj(string))
+
+        // Fast path: ASCII/UTF-8
+        if let Ok(s) = slice.to_str() {
+            return Ok(vm.new_pyobj(s));
+        }
+
+        // On Windows, locale strings use the ANSI code page encoding
+        #[cfg(windows)]
+        {
+            use windows_sys::Win32::Globalization::{CP_ACP, MultiByteToWideChar};
+            let bytes = slice.to_bytes();
+            unsafe {
+                let len = MultiByteToWideChar(
+                    CP_ACP,
+                    0,
+                    bytes.as_ptr(),
+                    bytes.len() as i32,
+                    ptr::null_mut(),
+                    0,
+                );
+                if len > 0 {
+                    let mut wide = vec![0u16; len as usize];
+                    MultiByteToWideChar(
+                        CP_ACP,
+                        0,
+                        bytes.as_ptr(),
+                        bytes.len() as i32,
+                        wide.as_mut_ptr(),
+                        len,
+                    );
+                    return Ok(vm.new_pyobj(String::from_utf16_lossy(&wide)));
+                }
+            }
+        }
+
+        Ok(vm.new_pyobj(String::from_utf8_lossy(slice.to_bytes()).into_owned()))
     }
 
     #[pyattr(name = "Error", once)]