Rustdoc: Comments (prose) are being parsed as tests

[rjframe]

Given multi-line doc-comments (/** */), indented one or more levels, the second paragraph is parsed as code.

With the following code:

    /** Summary

        a b
    */
    fn f() {}

I get the following output from cargo test (standard output only):

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out


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

failures:

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

error: aborting due to previous error

Couldn't compile the test.

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

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out

This only occurs with indented, multi-line doc-comments that have at least two paragraphs separated by a blank line.

This occurs on both stable and nightly.

[jfrimmel]

This is the intended behavior. In markdown (the syntax used in doc comments) an indentation of 4 spaces marks a code block, similar to the three-backtick-block. If you don't provide a source language (you cannot for indented blocks), rustdoc interprets it as Rust source code and hence compiles and tests it.

[ehuss]

Closing as a duplicate of #64162 and #59867.