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scott_w • today at 4:32 PM • 2 replies • view on HN

Correct, that's what I mean. I trust SQLite's devs to know more about this, so I trust what they wrote. There are parts of Rust code that are basically:

  do_thing().expect(...);
This branch is required by the code, even if it can't be reached, because the type system requires it. It's not possible to test this branch, therefore 100% coverage is impossible in those cases.

Replies

viraptor • today at 7:22 PM

You normally count/test branches at the original language level, not the compiled one. Otherwise we'd get VERY silly results like:

- counting foo().except() as 2 branches

- counting a simple loop as a missed branch, because it got unrolled and you didn't test it with 7,6,5,4,3,2,1 items

- failing on unused straight implementation of memcpy because your CPU supports SIMD and chose that alternative

Etc. The compiled version will be full of code you'll never run regardless of language.

Philpax • today at 4:58 PM

The type system does not require that. You can just discard the result:

  let _ = do_thing();