Enum rustc_trait_selection::traits::CodegenObligationError

source · [−]
pub enum CodegenObligationError {
    Ambiguity,
    Unimplemented,
    FulfillmentError,
}
Expand description

These are the error cases for codegen_select_candidate.

Variants

Ambiguity

Ambiguity can happen when monomorphizing during trans expands to some humongous type that never occurred statically – this humongous type can then overflow, leading to an ambiguous result. So report this as an overflow bug, since I believe this is the only case where ambiguity can result.

Unimplemented

This can trigger when we probe for the source of a 'static lifetime requirement on a trait object: impl Foo for dyn Trait {} has an implicit 'static bound. This can also trigger when we have a global bound that is not actually satisfied, but was included during typeck due to the trivial_bounds feature.

FulfillmentError

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The resulting type after obtaining ownership.
Creates owned data from borrowed data, usually by cloning. Read more
Uses borrowed data to replace owned data, usually by cloning. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.

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: 1 byte

Size for each variant:

  • Ambiguity: 0 bytes
  • Unimplemented: 0 bytes
  • FulfillmentError: 0 bytes