Chat Bot Mistakes Rust Vecs

A user testing a well-known online chat bot found it confidently incorrect about Rust's memory layout, claiming a Vec<bool> stores each bool as a single bit. In reality, a bool in Rust requires 1 byte (8 bits), as confirmed by the user's test program allocating 100 million bools in a Vec, which used about 100,000 kB, indicating roughly 1 byte per bool. The incident highlights that AI chat bots can provide plausible but false technical information.

Today I was using an online chat bot a well-known one and exploring changes to my Rust code. The chat bot confidently told me that in Rust a Vec of bool is encoded as a single bit per bool . I even asked if this was "truly" the case in Rust, as I was not familiar with this. In Rust the Vec type does not tend to have type-specific optimizations like for bool . It is supposed to be simple . The chat bot explained that yes, in Rust a Vector of bools only requires 1 bit per bool . This is not correct. A bool requires 1 byte in Rust, and 1 byte is 8 bits. Further online searches supported this—the chat bot was confidently wrong . I created a test program that allocated 100 million bools in a Vec , and then used the bools in an infinite loop. It required about 100000 kB, which means that about 1000 bools fit in 1 kB of memory. Which means that 1 bool requires about 1 byte. There has to be some source of truth—and AI chat bots can be wrong.