ialloc 0.0.0-2025-05-02

Allocator interface traits
Documentation 
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//! [`ExcessiveAlignmentRequestedError`], [`ExcessiveSliceRequestedError`] (and any future error types)

use crate::Alignment;

#[cfg(doc)] use core::alloc::LayoutError;
use core::fmt::{self, Debug, Display, Formatter};



/// The allocator explicitly rejected a zero-sized allocation, because they behave inconsistently.
///
/// This may be because:
/// -   A platform specific allocator fails on some but not all platforms.
/// -   Allocating 0 bytes succeeds, but reallocating to 0 bytes fails.
#[derive(Clone, Copy, Debug)] pub struct BannedZeroSizedAllocationsError;

/// More alignment was requested than the allocator could support.
#[derive(Clone, Copy, Debug)] pub struct ExcessiveAlignmentRequestedError {
    pub requested: Alignment,
    pub supported: Alignment,
}

/// A slice large enough to result in a [`LayoutError`] was requested.
#[derive(Clone, Copy, Debug)] pub struct ExcessiveSliceRequestedError {
    pub requested: usize,
}

impl Display for BannedZeroSizedAllocationsError  { fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { write!(f, "requested a 0-sized allocation, but those have inconsistent behavior with this allocator") } }
impl Display for ExcessiveAlignmentRequestedError { fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { write!(f, "requested {:?} alignment, but a maximum of {:?} is supported", self.requested, self.supported) } }
impl Display for ExcessiveSliceRequestedError     { fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { write!(f, "requested {} elements, but that would result in a LayoutError", self.requested) } }
impl From<BannedZeroSizedAllocationsError > for () { fn from(_: BannedZeroSizedAllocationsError) -> Self {} }
impl From<ExcessiveAlignmentRequestedError> for () { fn from(_: ExcessiveAlignmentRequestedError) -> Self {} }
impl From<ExcessiveSliceRequestedError    > for () { fn from(_: ExcessiveSliceRequestedError) -> Self {} }
#[cfg(feature = "std")] impl std::error::Error for BannedZeroSizedAllocationsError  { fn description(&self) -> &str { "requested a 0-sized allocation, but those have inconsistent behavior with this allocator" } }
#[cfg(feature = "std")] impl std::error::Error for ExcessiveAlignmentRequestedError { fn description(&self) -> &str { "requested more alignment than was supported" } }
#[cfg(feature = "std")] impl std::error::Error for ExcessiveSliceRequestedError     { fn description(&self) -> &str { "requested too many elements" } }
#[cfg(allocator_api = "*")] impl From<BannedZeroSizedAllocationsError > for core::alloc::AllocError { fn from(_: BannedZeroSizedAllocationsError ) -> Self { core::alloc::AllocError } }
#[cfg(allocator_api = "*")] impl From<ExcessiveAlignmentRequestedError> for core::alloc::AllocError { fn from(_: ExcessiveAlignmentRequestedError) -> Self { core::alloc::AllocError } }
#[cfg(allocator_api = "*")] impl From<ExcessiveSliceRequestedError    > for core::alloc::AllocError { fn from(_: ExcessiveSliceRequestedError    ) -> Self { core::alloc::AllocError } }