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Implement Error for TryReserveError #69792

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merged 4 commits into from
Mar 12, 2020
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Merged

Implement Error for TryReserveError #69792

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b900de0
Implement Error for TryReserveError
LenaWil Mar 6, 2020
88f8b88
Remove deprecated description function of TryReserveError
LenaWil Mar 10, 2020
599cd68
Format the match statement
LenaWil Mar 11, 2020
2c90a37
Reformat match statement to make the check pass
LenaWil Mar 11, 2020
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18 changes: 18 additions & 0 deletions src/liballoc/collections/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ pub use linked_list::LinkedList;
pub use vec_deque::VecDeque;

use crate::alloc::{Layout, LayoutErr};
use core::fmt::Display;

/// The error type for `try_reserve` methods.
#[derive(Clone, PartialEq, Eq, Debug)]
Expand Down Expand Up @@ -77,6 +78,23 @@ impl From<LayoutErr> for TryReserveError {
}
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@LenaWil2 LenaWil2 Mar 7, 2020 •
edited
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Maybe it's possible to return the LayoutErr as cause and source of the TryReserveError when passed here, although it would make the struct bigger.

}

#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
impl Display for TryReserveError {
fn fmt(
&self,
fmt: &mut core::fmt::Formatter<'_>,
) -> core::result::Result<(), core::fmt::Error> {
fmt.write_str("memory allocation failed")?;
let reason = match &self {
TryReserveError::CapacityOverflow => {
" because the computed capacity exceeded the collection's maximum"
}
TryReserveError::AllocError { .. } => " because the memory allocator returned a error",
Comment on lines +89 to +92
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I do dislike that this isn't formatted consistently, but rustfmt formatted it this way.

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The cleaner approach would be to move the match out of the write_str call and just assign the string to a variable IMO.

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It doesn't help with the formatting though, rustfmt transforms this:

#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
impl Display for TryReserveError {
    fn fmt(
        &self,
        fmt: &mut core::fmt::Formatter<'_>,
    ) -> core::result::Result<(), core::fmt::Error> {
        fmt.write_str("memory allocation failed")?;
        let reason = match &self {
            TryReserveError::CapacityOverflow => " because the computed capacity exceeded the collection's maximum",
            TryReserveError::AllocError { .. } => {
                " because the memory allocator returned a error"
            }
        };
        fmt.write_str(reason)
    }
}

Into this:

#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
impl Display for TryReserveError {
    fn fmt(
        &self,
        fmt: &mut core::fmt::Formatter<'_>,
    ) -> core::result::Result<(), core::fmt::Error> {
        fmt.write_str("memory allocation failed")?;
        let reason = match &self {
            TryReserveError::CapacityOverflow => {
                " because the computed capacity exceeded the collection's maximum"
            }
            TryReserveError::AllocError { .. } => " because the memory allocator returned a error",
        };
        fmt.write_str(reason)
    }
}

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@LenaWil2 LenaWil2 Mar 11, 2020 •
edited
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I tried to submit code in which both statements used braces, but that makes one of the checks fail.

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I think it's fine now, btw, it's a really minor issue.

};
fmt.write_str(reason)
}
}

/// An intermediate trait for specialization of `Extend`.
#[doc(hidden)]
trait SpecExtend<I: IntoIterator> {
Expand Down
3 changes: 3 additions & 0 deletions src/libstd/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -552,6 +552,9 @@ impl Error for char::ParseCharError {
}
}

#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
impl Error for alloc::collections::TryReserveError {}

// Copied from `any.rs`.
impl dyn Error + 'static {
/// Returns `true` if the boxed type is the same as `T`
Expand Down