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Fix bytes.decode() and str(b, encoding) looking up the codec for empty input #1227

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Merged
graalvmbot merged 1 commit into from
Oct 23, 2026
Merged

Fix bytes.decode() and str(b, encoding) looking up the codec for empty input #1227

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10 changes: 10 additions & 0 deletions graalpython/com.oracle.graal.python.test/src/tests/test_bytes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,16 @@ def __bytes__(self):
assert_raises(TypeError, bytes, errors="strict")


def test_decode_empty_skips_codec_lookup():
assert str(b'', 'x') == ''
assert str(bytearray(), 'x', 'y') == ''
assert str(memoryview(b''), 'x') == ''
assert b''.decode('x') == ''
assert bytearray().decode('x') == ''
assert_raises(LookupError, str, b'a', 'x')
assert_raises(TypeError, str, 1, 'x')


def test_from_ssize():
assert bytes(0) == b''
assert bytes(1) == b'\x00'
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6 changes: 6 additions & 0 deletions ....graal.python/src/com/oracle/graal/python/builtins/objects/bytes/BytesCommonBuiltins.java
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Expand Up @@ -203,9 +203,15 @@ protected ArgumentClinicProvider getArgumentClinic() {
@Specialization
static Object decode(VirtualFrame frame, Object self, TruffleString encoding, TruffleString errors,
@Bind Node inliningTarget,
@Cached GetBytesStorage getBytesStorage,
@Cached InlinedConditionProfile emptyStringProfile,
@Cached CodecsModuleBuiltins.DecodeNode decodeNode,
@Cached PyUnicodeCheckNode unicodeCheckNode,
@Cached PRaiseNode raiseNode) {
// like CPython's PyUnicode_FromEncodedObject: no codec lookup for empty input
if (emptyStringProfile.profile(inliningTarget, getBytesStorage.execute(inliningTarget, self).length() == 0)) {
return T_EMPTY_STRING;
}
Object result = decodeNode.executeWithStrings(frame, self, encoding, errors);
if (!unicodeCheckNode.execute(inliningTarget, result)) {
throw raiseNode.raise(inliningTarget, TypeError, DECODER_RETURNED_P_INSTEAD_OF_BYTES, encoding, result);
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