clap_builder/parser/
error.rs

1use crate::util::AnyValueId;
2
3/// Violation of [`ArgMatches`][crate::ArgMatches] assumptions
4#[derive(Clone, Debug)]
5#[allow(missing_copy_implementations)] // We might add non-Copy types in the future
6#[non_exhaustive]
7pub enum MatchesError {
8    /// Failed to downcast `AnyValue` to the specified type
9    #[non_exhaustive]
10    Downcast {
11        /// Type for value stored in [`ArgMatches`][crate::ArgMatches]
12        actual: AnyValueId,
13        /// The target type to downcast to
14        expected: AnyValueId,
15    },
16    /// Argument not defined in [`Command`][crate::Command]
17    #[non_exhaustive]
18    UnknownArgument {
19        // Missing `id` but blocked on a public id type which will hopefully come with `unstable-v4`
20    },
21}
22
23impl MatchesError {
24    #[cfg_attr(debug_assertions, track_caller)]
25    pub(crate) fn unwrap<T>(id: &str, r: Result<T, MatchesError>) -> T {
26        let err = match r {
27            Ok(t) => {
28                return t;
29            }
30            Err(err) => err,
31        };
32        panic!("Mismatch between definition and access of `{id}`. {err}",)
33    }
34}
35
36impl std::error::Error for MatchesError {}
37
38impl std::fmt::Display for MatchesError {
39    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
40        match self {
41            Self::Downcast { actual, expected } => {
42                writeln!(
43                    f,
44                    "Could not downcast to {expected:?}, need to downcast to {actual:?}"
45                )
46            }
47            Self::UnknownArgument {} => {
48                writeln!(f, "Unknown argument or group id.  Make sure you are using the argument id and not the short or long flags")
49            }
50        }
51    }
52}
53
54#[test]
55fn check_auto_traits() {
56    static_assertions::assert_impl_all!(
57        MatchesError: Send,
58        Sync,
59        std::panic::RefUnwindSafe,
60        std::panic::UnwindSafe,
61        Unpin
62    );
63}
clap_builder/parser/error.rs

clap_builder/parser/
error.rs
