The meaning is the same; the syntax is different. All triple-backtick codeblocks in doc comments, unless annotated 'ignore', are run as tests when you run `carg

The meaning is the same; the syntax is different. All triple-backtick codeblocks in doc comments, unless annotated 'ignore', are run as tests when you run `cargo test`. So from this file[0], this doc page[1] is generated. And there's more flexibility than 'run or ignore' too, e.g. one on that page is marked ```compile_fail,E0277 to fail the test if it compiles or has a different compilation error than expected. And then every code block known to be runnable has a Run button you can click to open the snippet in the Rust Playground. These are API docs, but mdBook[2], which generates documentation that looks like this[3], has a test command which checks the code blocks the same way. [0]: https://doc.rust-lang.org/stable/src/alloc/string.rs.html#76 https://doc.rust-lang.org/stable/src/alloc/string.rs.html#76 [1]: https://doc.rust-lang.org/stable/std/string/struct.String.html https://doc.rust-lang.org/stable/std/string/struct.String.ht... [2]: https://rust-lang.github.io/mdBook/ https://rust-lang.github.io/mdBook/ [3]: https://doc.rust-lang.org/book/ https://doc.rust-lang.org/book/