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fix: Swapcase must handle multibyte expansions #7559

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Merged
youknowone merged 1 commit into from
Apr 6, 2026
Merged

fix: Swapcase must handle multibyte expansions #7559

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6 changes: 3 additions & 3 deletions crates/vm/src/builtins/str.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1045,11 +1045,11 @@ impl PyStr {
let mut swapped_str = Wtf8Buf::with_capacity(self.data.len());
for c_orig in self.as_wtf8().code_points() {
let c = c_orig.to_char_lossy();
// to_uppercase returns an iterator, to_ascii_uppercase returns the char
// to_uppercase returns an iterator because case changes may be multiple bytes
if c.is_lowercase() {
swapped_str.push_char(c.to_ascii_uppercase());
swapped_str.extend(c.to_uppercase());
} else if c.is_uppercase() {
swapped_str.push_char(c.to_ascii_lowercase());
swapped_str.extend(c.to_lowercase());
} else {
swapped_str.push(c_orig);
}
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2 changes: 2 additions & 0 deletions extra_tests/snippets/builtin_str.py
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Expand Up @@ -235,6 +235,8 @@
assert not "😂".isidentifier()
assert not "123".isidentifier()

assert "Σίσυφος".swapcase() == "σΊΣΥΦΟΣ"

# String Formatting
assert "{} {}".format(1, 2) == "1 2"
assert "{0} {1}".format(2, 3) == "2 3"
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