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fix: panic with wrapping/unwrapping result return type assists by rmehri01 · Pul...

 11 months ago
source link: https://github.com/rust-lang/rust-analyzer/pull/15662
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With the wrap_return_type_in_result assist, the following code results in a panic (note the lack of a semicolon):

fn foo(num: i32) -> $0i32 {
    return num
}

=> 

thread 'handlers::wrap_return_type_in_result::tests::wrap_return_in_tail_position' panicked at crates/syntax/src/ted.rs:137:41:
called `Option::unwrap()` on a `None` value

I think this is because it first walks the body expression to change any return expressions and then walks all tail expressions, resulting in the return num being changed twice since it is both a return and in tail position. This can also happen when a match is in tail position and return is used in a branch for example. Not really sure how big of an issue this is in practice though since this seems to be the only case that is impacted and can be reduced to just num instead of return num.

This also occurs with the unwrap_result_return_type assist but panics with the following instead:

thread 'handlers::unwrap_result_return_type::tests::wrap_return_in_tail_position' panicked at /rustc/3223b0b5e8dadda3f76c3fd1a8d6c5addc09599e/library/alloc/src/string.rs:1766:29:
assertion failed: self.is_char_boundary(n)

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