Module expectation 

Re-exports

use rustc_middle::traits::ObligationCause; 🔒

use rustc_middle::ty; 🔒

use rustc_middle::ty::Ty; 🔒

use rustc_span::Span; 🔒

use super::FnCtxt; 🔒

use super::Expectation::*; 🔒

Enums

Expectation 🔒

When type-checking an expression, we propagate downward whatever type hint we are able in the form of an Expectation.