Rollup merge of #61279 - llogiq:implicit-option-main-doctests, r=GuillaumeGomez

implicit `Option`-returning doctests

This distinguishes `Option` and `Result`-returning doctests with implicit `main` method, where the former tests must end with `Some(())`.

Open question: Does this need a feature gate?

r? @GuillaumeGomez
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Mazdak Farrokhzad 2019-05-30 10:52:56 +02:00 committed by GitHub
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3 changed files with 31 additions and 1 deletions

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@ -253,6 +253,19 @@ conversion, so type inference fails because the type is not unique. Please note
that you must write the `(())` in one sequence without intermediate whitespace
so that rustdoc understands you want an implicit `Result`-returning function.
As of version 1.37.0, this simplification also works with `Option`s, which can
be handy to test e.g. iterators or checked arithmetic, for example:
```ignore
/// ```
/// let _ = &[].iter().next()?;
///# Some(())
/// ```
```
Note that the result must be a `Some(())` and this has to be written in one go.
In this case disambiguating the result isn't required.
## Documenting macros
Heres an example of documenting a macro:

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@ -530,8 +530,13 @@ pub fn make_test(s: &str,
prog.push_str(everything_else);
} else {
let returns_result = everything_else.trim_end().ends_with("(())");
let returns_option = everything_else.trim_end().ends_with("Some(())");
let (main_pre, main_post) = if returns_result {
("fn main() { fn _inner() -> Result<(), impl core::fmt::Debug> {",
(if returns_option {
"fn main() { fn _inner() -> Option<()> {"
} else {
"fn main() { fn _inner() -> Result<(), impl core::fmt::Debug> {"
},
"}\n_inner().unwrap() }")
} else {
("fn main() {\n", "\n}")

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@ -21,4 +21,16 @@
/// Err("This is returned from `main`, leading to panic")?;
/// Ok::<(), &'static str>(())
/// ```
///
/// This also works with `Option<()>`s now:
///
/// ```rust
/// Some(())
/// ```
///
/// ```rust,should_panic
/// let x: &[u32] = &[];
/// let _ = x.iter().next()?;
/// Some(())
/// ```
pub fn check_process_termination() {}