cargo_emit/
warning.rs

1/// Tells Cargo to print the formatted `warning` message.
2///
3/// This is equivalent to:
4///
5/// ```
6/// println!("cargo:warning=$args");
7/// ```
8///
9/// # Examples
10///
11/// Useful for showing when something expected (but not critical) has failed.
12///
13/// ```
14/// match std::env::current_dir() {
15///     Ok(dir) => { /* ... */ }
16///     Err(error) => cargo_emit::warning!(
17///         "Something suspicious is happening: {}",
18///         error,
19///     ),
20/// }
21/// ```
22///
23/// or, in case you want it to emit to a custom stream:
24///
25/// ```
26/// let mut stdout = std::io::stdout();
27/// match std::env::current_dir() {
28///     Ok(dir) => { /* ... */ }
29///     Err(error) => cargo_emit::warning!(
30///         to: stdout,
31///         "Something suspicious is happening: {}",
32///         error,
33///     ),
34/// }
35/// ```
36///
37/// Assuming you're building `my-crate`, you will see:
38///
39/// ```sh
40/// $ cargo build
41///    Compiling my-crate v0.1.0 (/path/to/my-crate)
42/// warning: Something suspicious is happening: ...
43/// ```
44#[macro_export]
45macro_rules! warning {
46    (to: $stream:expr, $($args:tt)+) => {
47        $crate::pair!(to: $stream, "warning", $($args)+)
48    };
49    ($($args:tt)+) => {
50        $crate::warning!(to: std::io::stdout(), $($args)+)
51    };
52}
53
54#[cfg(test)]
55mod tests {
56    #[test]
57    fn single_literal() {
58        insta::assert_display_snapshot!(
59            crate::capture_output(|output| {
60                crate::warning!(
61                    to: output,
62                    "WARNING"
63                );
64            }),
65            @"cargo:warning=WARNING\n"
66        );
67    }
68
69    #[test]
70    fn single_formatted_by_index() {
71        // Formatted argument:
72        insta::assert_display_snapshot!(
73            crate::capture_output(|output| {
74                crate::warning!(
75                    to: output,
76                    "{}", "WARNING"
77                );
78            }),
79            @"cargo:warning=WARNING\n"
80        );
81    }
82
83    #[test]
84    fn single_formatted_by_key() {
85        // Formatted argument:
86        insta::assert_display_snapshot!(
87            crate::capture_output(|output| {
88                crate::warning!(
89                    to: output,
90                    "{warning}", warning = "WARNING"
91                );
92            }),
93            @"cargo:warning=WARNING\n"
94        );
95    }
96}
cargo_emit/warning.rs

cargo_emit/
warning.rs
