Macro __phantom_struct

macro_rules! __phantom_struct {
    (
        $(#[$meta:meta])*
        $vis:vis
        $Name:ident
        []
        []
    ) => { ... };
    (
        $(#[$meta:meta])*
        $vis:vis
        $Name:ident
        [$($lt:lifetime),+ $(,)?]
        []
    ) => { ... };
    (
        $(#[$meta:meta])*
        $vis:vis
        $Name:ident
        []
        [$($gen:ident),+ $(,)?]
    ) => { ... };
    (
        $(#[$meta:meta])*
        $vis:vis
        $Name:ident
        [$($lt:lifetime),+ $(,)?]
        [$($gen:ident),+ $(,)?]
    ) => { ... };
}

Generates a zero-sized or PhantomData-backed marker struct.

This is an internal helper used by plugin_context, define_family, and other macros that need to produce marker structs which may carry lifetime or type parameters purely at the type level without any runtime storage.

Syntax

__phantom_struct!(
    #[attributes]   // optional
    VISIBILITY      // pub, pub(crate), or empty
    NAME            // struct identifier
    [LIFETIMES]     // e.g. ['a, 'b] or []
    [GENERICS]      // e.g. [T, U]   or []
)

Variants

Lifetimes	Generics	Generated struct
[]	[]	struct Foo;
['a]	[]	struct Foo<'a>(PhantomData<(&'a (),)>)
[]	[T]	struct Foo<T>(PhantomData<(T,)>)
['a]	[T]	struct Foo<'a, T>(PhantomData<(T, &'a ())>)