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fix(sema): reject subscripting zero-length bytes literal #1886

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fix(sema): reject subscripting zero-length bytes literal #1886

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11 changes: 11 additions & 0 deletions src/sema/expression/subscript.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,17 @@ pub(super) fn array_subscript(
index = index.cast(&index.loc(), index_ty.deref_any(), true, ns, diagnostics)?;

let deref_ty = array_ty.deref_any();

// Subscripting a zero-length bytes type is always out of bounds.
// Reject early to avoid a u8 underflow in codegen (array_length - 1).
if let Type::Bytes(0) = deref_ty {
diagnostics.push(Diagnostic::error(
*loc,
"array subscript is out of bounds".to_string(),
));
return Err(());
}

match deref_ty {
Type::Bytes(_) | Type::Array(..) | Type::DynamicBytes | Type::Slice(_) => {
if array_ty.is_contract_storage() {
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