PassMode in rustc_target::callconv - Rust
Description: API documentation for the Rust `PassMode` enum in crate `rustc_target`.

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## PassMode

# Enum PassMode

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    pub enum PassMode {
        Ignore,
        Direct(ArgAttributes),
        Pair(ArgAttributes, ArgAttributes),
        Cast {
            pad_i32: bool,
            cast: Box<CastTarget>,
        },
        Indirect {
            attrs: ArgAttributes,
            meta_attrs: Option<ArgAttributes>,
            on_stack: bool,
        },
    }

## Variants§

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### Ignore

Ignore the argument.

The argument is a ZST.

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### Direct(ArgAttributes)

Pass the argument directly.

The argument has a layout abi of `Scalar` or `Vector`. Unfortunately due to past mistakes, in rare cases on wasm, it can also be `Aggregate`. This is bad since it leaks LLVM implementation details into the ABI. (Also see https://github.com/rust-lang/rust/issues/115666.)

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### Pair(ArgAttributes, ArgAttributes)

Pass a pair’s elements directly in two arguments.

The argument has a layout abi of `ScalarPair`.

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### Cast

Pass the argument after casting it. See the `CastTarget` docs for details.

`pad_i32` indicates if a `Reg::i32()` dummy argument is emitted before the real argument.

#### Fields

§`pad_i32: bool`
§`cast: Box<CastTarget>`
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### Indirect

Pass the argument indirectly via a hidden pointer.

The `meta_attrs` value, if any, is for the metadata (vtable or length) of an unsized argument. (This is the only mode that supports unsized arguments.)

`on_stack` defines that the value should be passed at a fixed stack offset in accordance to the ABI rather than passed using a pointer. This corresponds to the `byval` LLVM argument attribute. The `byval` argument will use a byte array with the same size as the Rust type (which ensures that padding is preserved and that we do not rely on LLVM’s struct layout), and will use the alignment specified in `attrs.pointee_align` (if `Some`) or the type’s alignment (if `None`). This means that the alignment will not always match the Rust type’s alignment; see documentation of `pass_by_stack_offset` for more info.

`on_stack` cannot be true for unsized arguments, i.e., when `meta_attrs` is `Some`.

#### Fields

§`attrs: ArgAttributes`
§`meta_attrs: Option<ArgAttributes>`
§`on_stack: bool`

## Implementations§

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### impl PassMode

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#### pub fn eq_abi(&self, other: &Self) -> bool

Checks if these two `PassMode` are equal enough to be considered “the same for all function call ABIs”. However, the `Layout` can also impact ABI decisions, so that needs to be compared as well!

## Trait Implementations§

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### impl Clone for PassMode

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#### fn clone(&self) -> PassMode

Returns a duplicate of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl Debug for PassMode

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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### impl Hash for PassMode

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#### fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl<__CTX> HashStable<__CTX> for PassMode
where __CTX: HashStableContext,

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#### fn hash_stable(&self, __hcx: &mut __CTX, __hasher: &mut StableHasher)

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### impl PartialEq for PassMode

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#### fn eq(&self, other: &PassMode) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl Eq for PassMode

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### impl StructuralPartialEq for PassMode

## Auto Trait Implementations§

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### impl DynSend for PassMode

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### impl DynSync for PassMode

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### impl Freeze for PassMode

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### impl RefUnwindSafe for PassMode

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### impl Send for PassMode

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### impl Sync for PassMode

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### impl Unpin for PassMode

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### impl UnsafeUnpin for PassMode

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### impl UnwindSafe for PassMode

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment

Alignment of `Self`.
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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> AnyEq for T
where T: Any + PartialEq,

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#### fn equals(&self, other: &(dyn Any + 'static)) -> bool

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#### fn as_any(&self) -> &(dyn Any + 'static)

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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> CloneToUninit for T
where T: Clone,

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#### unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (`clone_to_uninit`)
Performs copy-assignment from `self` to `dest`. Read more
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### impl<T> DynClone for T
where T: Clone,

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#### fn __clone_box(&self, _: Private) -> *mut ()

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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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### impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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#### fn equivalent(&self, key: &K) -> bool

Compare self to `key` and return `true` if they are equal.
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> IntoEither for T

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#### fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts `self` into a `Left` variant of `Either<Self, Self>` if `into_left` is `true`. Converts `self` into a `Right` variant of `Either<Self, Self>` otherwise. Read more
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#### fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts `self` into a `Left` variant of `Either<Self, Self>` if `into_left(&self)` returns `true`. Converts `self` into a `Right` variant of `Either<Self, Self>` otherwise. Read more
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### impl<T> Pointable for T

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#### const ALIGN: usize

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<T> ToOwned for T
where T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<T> ErasedDestructor for T
where T: 'static,

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 40 bytes

Size for each variant:

- `Ignore`: 0 bytes
- `Direct`: 23 bytes
- `Pair`: 39 bytes
- `Cast`: 15 bytes
- `Indirect`: 39 bytes