Auto merge of #87375 - fee1-dead:move-constness-to-traitpred, r=oli-obk

Try filtering out non-const impls when we expect const impls

**TL;DR**: Associated types on const impls are now bounded; we now disallow calling a const function with bounds when the specified type param only has a non-const impl.

r? `@oli-obk`

compiler/rustc_infer/src/traits/engine.rs

@@ -1,5 +1,6 @@
 use crate::infer::InferCtxt;
 use crate::traits::Obligation;
+use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::{self, ToPredicate, Ty, WithConstness};
 
@@ -49,11 +50,28 @@ pub trait TraitEngine<'tcx>: 'tcx {
         infcx: &InferCtxt<'_, 'tcx>,
     ) -> Result<(), Vec<FulfillmentError<'tcx>>>;
 
+    fn select_all_with_constness_or_error(
+        &mut self,
+        infcx: &InferCtxt<'_, 'tcx>,
+        _constness: hir::Constness,
+    ) -> Result<(), Vec<FulfillmentError<'tcx>>> {
+        self.select_all_or_error(infcx)
+    }
+
     fn select_where_possible(
         &mut self,
         infcx: &InferCtxt<'_, 'tcx>,
     ) -> Result<(), Vec<FulfillmentError<'tcx>>>;
 
+    // FIXME this should not provide a default body for chalk as chalk should be updated
+    fn select_with_constness_where_possible(
+        &mut self,
+        infcx: &InferCtxt<'_, 'tcx>,
+        _constness: hir::Constness,
+    ) -> Result<(), Vec<FulfillmentError<'tcx>>> {
+        self.select_where_possible(infcx)
+    }
+
     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;
 }
 

compiler/rustc_infer/src/traits/util.rs

@@ -124,7 +124,7 @@ impl Elaborator<'tcx> {
 
         let bound_predicate = obligation.predicate.kind();
         match bound_predicate.skip_binder() {
-            ty::PredicateKind::Trait(data, _) => {
+            ty::PredicateKind::Trait(data) => {
                 // Get predicates declared on the trait.
                 let predicates = tcx.super_predicates_of(data.def_id());