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fix: handle Unicode characters correctly in mutator byte offset calculation #2832

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fix: handle Unicode characters correctly in mutator byte offset calculation #2832

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e5d2efa
fix: handle Unicode characters correctly in mutator byte offset calcu…
stevennevins Dec 8, 2025
da905c8
Merge branch 'dev' into fix/mutator-unicode-byte-offsets
stevennevins Dec 11, 2025
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4 changes: 3 additions & 1 deletion slither/formatters/utils/patches.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@

from slither.core.compilation_unit import SlitherCompilationUnit


# pylint: disable=too-many-arguments
def create_patch(
result: Dict,
Expand All @@ -31,7 +32,8 @@ def apply_patch(original_txt: bytes, patch: Dict, offset: int) -> Tuple[bytes, i
patched_txt += original_txt[int(patch["end"] + offset) :]

# Keep the diff of text added or sub, in case of multiple patches
patch_length_diff = len(patch["new_string"]) - (patch["end"] - patch["start"])
# Note: must use byte length since patch offsets are byte offsets from solc
patch_length_diff = len(patch["new_string"].encode("utf8")) - (patch["end"] - patch["start"])
return patched_txt, patch_length_diff + offset


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9 changes: 6 additions & 3 deletions slither/tools/mutator/utils/testing_generated_mutant.py
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Expand Up @@ -96,12 +96,15 @@ def test_patch( # pylint: disable=too-many-arguments
function to verify whether each patch is caught by tests
returns: 0 (uncaught), 1 (caught), or 2 (compilation failure)
"""
with open(file, "r", encoding="utf8") as filepath:
with open(file, "rb") as filepath:
content = filepath.read()
# Perform the replacement based on the index values
replaced_content = content[: patch["start"]] + patch["new_string"] + content[patch["end"] :]
# Note: patch offsets are byte offsets from solc, so we must work with bytes
replaced_content = (
content[: patch["start"]] + patch["new_string"].encode("utf8") + content[patch["end"] :]
)
# Write the modified content back to the file
with open(file, "w", encoding="utf8") as filepath:
with open(file, "wb") as filepath:
filepath.write(replaced_content)

if compile_generated_mutant(file, mappings):
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