vendor/packed_simd/src/api/from/from_vector.rs

//! Implements `From` and `Into` for vector types.

macro_rules! impl_from_vector {
    ([$elem_ty:ident; $elem_count:expr]: $id:ident | $test_tt:tt
     | $source:ident) => {
        impl From<$source> for $id {
            #[inline]
            fn from(source: $source) -> Self {
                fn static_assert_same_number_of_lanes<T, U>()
                where
                    T: crate::sealed::Simd,
                    U: crate::sealed::Simd<LanesType = T::LanesType>,
                {
                }
                use crate::llvm::simd_cast;
                static_assert_same_number_of_lanes::<$id, $source>();
                Simd(unsafe { simd_cast(source.0) })
            }
        }

        // FIXME: `Into::into` is not inline, but due to the blanket impl in
        // `std`, which is not marked `default`, we cannot override it here
        // with specialization.

        /*
           impl Into<$id> for $source {
               #[inline]
               fn into(self) -> $id {
                   unsafe { simd_cast(self) }
               }
           }
        */

        test_if! {
            $test_tt:
            paste::item! {
                pub mod [<$id _from_ $source>] {
                    use super::*;
                    #[cfg_attr(not(target_arch = "wasm32"), test)]
                    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
                    fn from() {
                        assert_eq!($id::lanes(), $source::lanes());
                        let source: $source = Default::default();
                        let vec: $id = Default::default();

                        let e = $id::from(source);
                        assert_eq!(e, vec);

                        let e: $id = source.into();
                        assert_eq!(e, vec);
                    }
                }
            }
        }
    };
}

macro_rules! impl_from_vectors {
    ([$elem_ty:ident; $elem_count:expr]: $id:ident | $test_tt:tt
     | $($source:ident),*) => {
        $(
            impl_from_vector!(
                [$elem_ty; $elem_count]: $id | $test_tt | $source
            );
        )*
    }
}