Eliminate an unreachable codepath from String::from_utf8_lossy #91241
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Utf8Lossy's Iterator implementation ensures that only the final chunk has an empty slice for broken. Thus the only way the first chunk could have an empty broken is if it is the final chunk, i.e. there is only one chunk total. And the only way that there could be one chunk total is if the whole input is valid utf8 and non-empty. That condition has already been handled by an early return, so at the point that the first REPLACEMENT is being pushed, it's impossible for first_broken to be empty.
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Finished benchmarking commit (4919988): comparison url. Summary: This benchmark run did not return any relevant changes. If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. @rustbot label: -perf-regression |
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Utf8Lossy'sIteratorimplementation ensures that only the final chunk has an empty slice forbroken:rust/library/core/src/str/lossy.rs
Lines 46 to 47 in dd549dc
Thus the only way the first chunk could have an empty
brokenis if it is the final chunk, i.e. there is only one chunk total. And the only way that there could be one chunk total with an emptybrokenis if the whole input is valid utf8 and non-empty.That condition has already been handled by an early return, so at the point that the first
REPLACEMENTis being pushed, it's impossible forfirst_brokento be empty.