From b682ec3bbe8716d7c9710f64be3075b08fd2eece Mon Sep 17 00:00:00 2001
From: Copilot <198982749+Copilot@users.noreply.github.com>
Date: Sat, 4 Apr 2026 14:45:30 +0900
Subject: [PATCH] Fix `str.zfill()` width calculation for non-ASCII strings
 (#7534)

---
 crates/vm/src/anystr.rs             | 4 ++++
 extra_tests/snippets/builtin_str.py | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/crates/vm/src/anystr.rs b/crates/vm/src/anystr.rs
index 79b62a58a..a9369bf06 100644
--- a/crates/vm/src/anystr.rs
+++ b/crates/vm/src/anystr.rs
@@ -396,6 +396,10 @@ pub trait AnyStr {
 
     fn py_zfill(&self, width: isize) -> Vec<u8> {
         let width = width.to_usize().unwrap_or(0);
+        let char_len = self.elements().count();
+        let width = self
+            .bytes_len()
+            .saturating_add(width.saturating_sub(char_len));
         rustpython_common::str::zfill(self.as_bytes(), width)
     }
 
diff --git a/extra_tests/snippets/builtin_str.py b/extra_tests/snippets/builtin_str.py
index 415156184..12f97ac61 100644
--- a/extra_tests/snippets/builtin_str.py
+++ b/extra_tests/snippets/builtin_str.py
@@ -61,6 +61,9 @@ assert a.endswith(("A", "lo"))
 assert not a.endswith("on")
 assert not a.endswith(("A", "ll"))
 assert a.zfill(8) == "000Hallo"
+assert "á".zfill(4) == "000á"
+assert "🙂".zfill(5) == "0000🙂"
+assert "+あ".zfill(5) == "+000あ"
 assert a.isalnum()
 assert not a.isdigit()
 assert not a.isdecimal()