1 files changed, 45 insertions, 0 deletions
diff --git a/compiler/rustc_traits/src/normalize_projection_ty.rs b/compiler/rustc_traits/src/normalize_projection_ty.rs
new file mode 100644
index 000000000..98bb42c9a
--- /dev/null
+++ b/compiler/rustc_traits/src/normalize_projection_ty.rs
@@ -0,0 +1,45 @@
+use rustc_infer::infer::canonical::{Canonical, QueryResponse};
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_infer::traits::TraitEngineExt as _;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
+use rustc_trait_selection::infer::InferCtxtBuilderExt;
+use rustc_trait_selection::traits::query::{
+    normalize::NormalizationResult, CanonicalProjectionGoal, NoSolution,
+};
+use rustc_trait_selection::traits::{self, ObligationCause, SelectionContext};
+use std::sync::atomic::Ordering;
+
+pub(crate) fn provide(p: &mut Providers) {
+    *p = Providers { normalize_projection_ty, ..*p };
+}
+
+fn normalize_projection_ty<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    goal: CanonicalProjectionGoal<'tcx>,
+) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
+    debug!("normalize_provider(goal={:#?})", goal);
+
+    tcx.sess.perf_stats.normalize_projection_ty.fetch_add(1, Ordering::Relaxed);
+    tcx.infer_ctxt().enter_canonical_trait_query(
+        &goal,
+        |infcx, fulfill_cx, ParamEnvAnd { param_env, value: goal }| {
+            let selcx = &mut SelectionContext::new(infcx);
+            let cause = ObligationCause::dummy();
+            let mut obligations = vec![];
+            let answer = traits::normalize_projection_type(
+                selcx,
+                param_env,
+                goal,
+                cause,
+                0,
+                &mut obligations,
+            );
+            fulfill_cx.register_predicate_obligations(infcx, obligations);
+            // FIXME(associated_const_equality): All users of normalize_projection_ty expected
+            // a type, but there is the possibility it could've been a const now. Maybe change
+            // it to a Term later?
+            Ok(NormalizationResult { normalized_ty: answer.ty().unwrap() })
+        },
+    )
+}