wasm_bindgen/rt/
marker.rs

1/// Marker trait for types that support `#[wasm_bindgen(constructor)]`.
2#[cfg_attr(
3    wbg_diagnostic,
4    diagnostic::on_unimplemented(
5        message = "JavaScript constructors are not supported for `{Self}`",
6        label = "this function cannot be the constructor of `{Self}`",
7        note = "`#[wasm_bindgen(constructor)]` is only supported for `struct`s and cannot be used for `enum`s.",
8        note = "Consider removing the `constructor` option and using a regular static method instead."
9    )
10)]
11pub trait SupportsConstructor {}
12pub struct CheckSupportsConstructor<T: SupportsConstructor>(T);
13
14/// Marker trait for types that support `#[wasm_bindgen(getter)]` or
15/// `#[wasm_bindgen(Setter)]` on instance methods.
16#[cfg_attr(
17    wbg_diagnostic,
18    diagnostic::on_unimplemented(
19        message = "JavaScript instance getters and setters are not supported for `{Self}`",
20        label = "this method cannot be a getter or setter for `{Self}`",
21        note = "`#[wasm_bindgen(getter)]` and `#[wasm_bindgen(setter)]` are only supported for `struct`s and cannot be used for `enum`s.",
22    )
23)]
24pub trait SupportsInstanceProperty {}
25pub struct CheckSupportsInstanceProperty<T: SupportsInstanceProperty>(T);
26
27/// Marker trait for types that support `#[wasm_bindgen(getter)]` or
28/// `#[wasm_bindgen(Setter)]` on static methods.
29#[cfg_attr(
30    wbg_diagnostic,
31    diagnostic::on_unimplemented(
32        message = "JavaScript static getters and setters are not supported for `{Self}`",
33        label = "this static function cannot be a static getter or setter on `{Self}`",
34        note = "`#[wasm_bindgen(getter)]` and `#[wasm_bindgen(setter)]` are only supported for `struct`s and cannot be used for `enum`s.",
35    )
36)]
37pub trait SupportsStaticProperty {}
38pub struct CheckSupportsStaticProperty<T: SupportsStaticProperty>(T);
39
40#[cfg(all(feature = "std", target_arch = "wasm32", panic = "unwind"))]
41use core::panic::UnwindSafe;
42
43/// Marker trait for types that are UnwindSafe only when building with panic unwind
44pub trait MaybeUnwindSafe {}
45
46#[cfg(all(feature = "std", target_arch = "wasm32", panic = "unwind"))]
47impl<T: UnwindSafe + ?Sized> MaybeUnwindSafe for T {}
48
49#[cfg(not(all(feature = "std", target_arch = "wasm32", panic = "unwind")))]
50impl<T: ?Sized> MaybeUnwindSafe for T {}
51
52/// Private marker trait for erasable generics - types with this trait have the same
53/// repr for all generic param values, and can therefore be transmuted on
54/// the singular Repr type representation on ABI boundaries.
55///
56/// # Safety
57/// This type must only be implemented on types known to be repr equivalent
58/// to their Repr type.
59// #[cfg_attr(
60//     wbg_diagnostic,
61//     diagnostic::on_unimplemented(
62//         label = "generic parameter is not a valid Wasm Bindgen ErasableGeneric type",
63//         note = "\nRecommendation: Add the direct `: wasm_bindgen::JsGeneric` convenience trait bound for JsValue generics, instead of `ErasableGeneric`.\n",
64//     )
65// )]
66pub unsafe trait ErasableGeneric {
67    /// The singular concrete type that all generic variants can be transmuted on
68    type Repr: 'static;
69}
70
71unsafe impl<T: ErasableGeneric> ErasableGeneric for &mut T {
72    type Repr = &'static mut T::Repr;
73}
74
75unsafe impl<T: ErasableGeneric> ErasableGeneric for &T {
76    type Repr = &'static T::Repr;
77}
78
79/// Trait bound marker for types that are passed as an own generic type.
80/// Encapsulating the ErasableGeneric invariant that must be maintained, that
81/// the repr of the type is the type of the concrete target type repr.
82/// This is useful to provide simple debuggable trait bounds for codegen.
83#[cfg_attr(
84    wbg_diagnostic,
85    diagnostic::on_unimplemented(
86        message = "Unable to call function, since the concrete generic argument or return value cannot be type-erased into the expected generic repr type for the function",
87        label = "passed concrete generic type does not match the expected generic repr type",
88        note = "Make sure that all erasable generic parameters satisfy the trait bound `ErasableGeneric` with the correct repr. Wasm Bindgen generic parameters and return values for functions are defined to work for specific type-erasable generic repr types only.",
89    )
90)]
91pub trait ErasableGenericOwn<ConcreteTarget>: ErasableGeneric {}
92
93impl<T, ConcreteTarget> ErasableGenericOwn<ConcreteTarget> for T
94where
95    ConcreteTarget: ErasableGeneric,
96    T: ErasableGeneric<Repr = <ConcreteTarget as ErasableGeneric>::Repr>,
97{
98}
99
100/// Trait bound marker for types that are passed as a borrowed generic type.
101/// Encapsulating the ErasableGeneric invariant that must be maintained, that
102/// the repr of the type is the type of the concrete target type repr.
103/// This is useful to provide simple debuggable trait bounds for codegen.
104#[cfg_attr(
105    wbg_diagnostic,
106    diagnostic::on_unimplemented(
107        message = "Unable to call this function, since the concrete generic argument or return value cannot be type-erased into the expected generic repr type for the function",
108        label = "concrete generic type does not match the expected generic repr type",
109        note = "Make sure that all erasable generic parameters satisfy the trait bound `ErasableGeneric` with the correct repr. Wasm Bindgen generic parameters and return values for functions are defined to work for specific type-erasable generic repr types only.",
110    )
111)]
112pub trait ErasableGenericBorrow<Target: ?Sized> {}
113
114impl<'a, T: ?Sized + 'a, ConcreteTarget: ?Sized + 'static> ErasableGenericBorrow<ConcreteTarget>
115    for T
116where
117    &'static ConcreteTarget: ErasableGeneric,
118    &'a T: ErasableGeneric<Repr = <&'static ConcreteTarget as ErasableGeneric>::Repr>,
119{
120}
121
122/// Trait bound marker for types that are passed as a mutable borrowed generic type.
123/// Encapsulating the ErasableGeneric invariant that must be maintained, that
124/// the repr of the type is the type of the concrete target type repr.
125/// This is useful to provide simple debuggable trait bounds for codegen.
126#[cfg_attr(
127    wbg_diagnostic,
128    diagnostic::on_unimplemented(
129        message = "Unable to call this function, since the concrete generic argument or return value cannot be type-erased into the expected generic repr type for the function",
130        label = "concrete generic type does not match the expected generic repr type",
131        note = "Make sure that all erasable generic parameters satisfy the trait bound `ErasableGeneric` with the correct repr. Wasm Bindgen generic parameters and return values for functions are defined to work for specific type-erasable generic repr types only.",
132    )
133)]
134pub trait ErasableGenericBorrowMut<Target: ?Sized> {}
135
136impl<'a, T: ?Sized + 'a, ConcreteTarget: ?Sized + 'static> ErasableGenericBorrowMut<ConcreteTarget>
137    for T
138where
139    &'static mut ConcreteTarget: ErasableGeneric,
140    &'a mut T: ErasableGeneric<Repr = <&'static mut ConcreteTarget as ErasableGeneric>::Repr>,
141{
142}
wasm_bindgen/rt/marker.rs

wasm_bindgen/rt/
marker.rs
