rustc_next_trait_solver/solve/project_goals/
free_alias.rs

1//! Computes a projection goal for inherent associated types,
2//! `#![feature(lazy_type_alias)]` and `#![feature(type_alias_impl_trait)]`.
3//!
4//! Since a free alias is never ambiguous, this just computes the `type_of` of
5//! the alias and registers the where-clauses of the type alias.
6
7use rustc_type_ir::solve::QueryResultOrRerunNonErased;
8use rustc_type_ir::{self as ty, Interner, Unnormalized};
9
10use crate::delegate::SolverDelegate;
11use crate::solve::{Certainty, EvalCtxt, Goal, GoalSource};
12
13impl<D, I> EvalCtxt<'_, D>
14where
15    D: SolverDelegate<Interner = I>,
16    I: Interner,
17{
18    pub(super) fn normalize_free_alias(
19        &mut self,
20        goal: Goal<I, ty::ProjectionPredicate<I>>,
21    ) -> QueryResultOrRerunNonErased<I> {
22        let cx = self.cx();
23        let free_alias = goal.predicate.projection_term;
24
25        // Check where clauses
26        self.add_goals(
27            GoalSource::Misc,
28            cx.predicates_of(free_alias.expect_free_def_id().into())
29                .iter_instantiated(cx, free_alias.args)
30                .map(Unnormalized::skip_norm_wip)
31                .map(|pred| goal.with(cx, pred)),
32        )?;
33
34        let actual = match free_alias.kind {
35            ty::AliasTermKind::FreeTy { def_id } => {
36                let free = cx.type_of(def_id.into()).instantiate(cx, free_alias.args);
37                let free = self.normalize(GoalSource::Misc, goal.param_env, free)?;
38                free.into()
39            }
40            ty::AliasTermKind::FreeConst { def_id } if cx.is_type_const(def_id.into()) => {
41                let free = cx.const_of_item(def_id.into()).instantiate(cx, free_alias.args);
42                let free = self.normalize(GoalSource::Misc, goal.param_env, free)?;
43
44                free.into()
45            }
46            ty::AliasTermKind::FreeConst { .. } => {
47                return self.evaluate_const_and_instantiate_projection_term(
48                    goal.param_env,
49                    free_alias,
50                    goal.predicate.term,
51                    free_alias.expect_ct(),
52                );
53            }
54            kind => {
    ::core::panicking::panic_fmt(format_args!("expected free alias, found {0:?}",
            kind));
}panic!("expected free alias, found {kind:?}"),
55        };
56
57        self.push_const_arg_has_type_goal(goal.param_env, goal.predicate.projection_term, actual)?;
58        self.eq(goal.param_env, goal.predicate.term, actual)?;
59        self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
60    }
61}
rustc_next_trait_solver/solve/project_goals/free_alias.rs

rustc_next_trait_solver/solve/project_goals/
free_alias.rs
