Faulty doctest detection under #[doc] generated OUTER_BLOCK_DOC

[ipaljak-tbtl]

I've noticed cargo test failing in certain scenarios when using a #[doc] attribute to generate a multi-line rustdoc documentation of some type. I've succeeded to reproduce this issue at the playground on a small example.

I tried to run cargo test on this code (Link to Playground):

#[doc = "A list of items:\n\t- item 1\n\n\t- item 2\n"]
struct SomeStruct {}

fn main() {
    for counter in 0..1 {
        println!("{:?}", counter);
    }
}

I expected to see this happen: cargo test passes, no errors detected.

Instead, this happened: A doctest was detected, and failed with the following error:

running 1 test
test src/lib.rs - SomeStruct (line 4) ... FAILED

failures:

---- src/lib.rs - SomeStruct (line 4) stdout ----
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `2`
 --> src/lib.rs:5:8
  |
3 | - item 2
  |        ^ expected one of 8 possible tokens

error: aborting due to previous error

Couldn't compile the test.

failures:
    src/lib.rs - SomeStruct (line 4)

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.03s

Meta

The same behavior can be observed in stable (1.67.1), beta (1.68.0-beta.4 (2023-02-09 a6d8057f098ab3cebe5a)), and nightly (1.69.0-nightly (2023-02-12 5b8f284536d00ba649ca)) channels within the rust playground.

I've also observed that this error does not occur in some previous releases, for example:

> rustc --version --verbose

rustc 1.66.1 (90743e729 2023-01-10)
binary: rustc
commit-hash: 90743e7298aca107ddaa0c202a4d3604e29bfeb6
commit-date: 2023-01-10
host: x86_64-unknown-linux-gnu
release: 1.66.1
LLVM version: 15.0.2

[lukas-code]

Your doc comment contains an indented code block that is executed as a doc test.

For me this reproduces on 1.66.1 as well.

See also #100225 #88590.

[ipaljak-tbtl]

Ah, I see, not a bug then 😄

Thanks!