Fix unspecified behavior in LLVM and UB in Rust. #130
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Lexical itself used a high-level vector which is then directly cast to a String using uninitialized memory under the hood. Since the behavior never relied on the values of the reads, this wasn't ever seen as an issue, however, anything besides using `ptr::write` can invoke UB which lexical-core and lower-level APIs do not always use: they often use index (read-write) assignment. This initializes the underlying buffer of the vector to avoid any risk of potential UB.
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Lexical itself used a high-level vector which is then directly cast to a String using uninitialized memory under the hood. Since the behavior never relied on the values of the reads, this wasn't ever seen as an issue, however, anything besides using
ptr::writecan invoke UB which lexical-core and lower-level APIs do not always use: they often use index (read-write) assignment. This initializes the underlying buffer of the vector to avoid any risk of potential UB.