Enum rustc_trait_selection::traits::solve::GoalSource

pub enum GoalSource {
    Misc,
    ImplWhereBound,
}

Why a specific goal has to be proven.

This is necessary as we treat nested goals different depending on their source.

Variants

Misc

ImplWhereBound

We’re proving a where-bound of an impl.

FIXME(-Znext-solver=coinductive): Explain how and why this changes whether cycles are coinductive.

This also impacts whether we erase constraints on overflow. Erasing constraints is generally very useful for perf and also results in better error messages by avoiding spurious errors. We do not erase overflow constraints in normalizes-to goals unless they are from an impl where-clause. This is necessary due to backwards compatability, cc trait-system-refactor-initiatitive#70.

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:

• Misc: 0 bytes
• ImplWhereBound: 0 bytes