[twic]

> #93066: The Decoder trait used for metadata decoding was fallible, using Result throughout. But decoding failures should only happen if something highly unexpected happens (e.g. metadata is corrupted) and on failure the calling code would just abort. This PR changed Decoder to be infallible throughout—panicking immediately instead of panicking slightly later—thus avoiding lots of pointless Result propagation, for wins across many benchmarks of up to 2%.

Interesting insight into the cost of Result-based error handling.

[jcelerier]

not surprising though, this is the exact same scenario than with C++ exceptions. if your code is on the happy path, they are consistently faster than error codes

[dthul]

I was wondering whether the Rust compiler could treat Result enums specially and implement them as panics under the hood. But I guess such optimizations are not really feasible because they might change behavior when unwinding through FFI for example. Not even speaking of the possibility that each stack frame is able to convert the error type, unlike exceptions.

[Inityx]

It would also change the behavior of panicking destructors on the unwind path, since a second panic during an unwind causes an abort instead of another unwind