Auto merge of #89247 - fee1-dead:const-eval-select, r=oli-obk

Add `const_eval_select` intrinsic

Adds an intrinsic that calls a given function when evaluated at compiler time, but generates a call to another function when called at runtime.

See https://github.com/rust-lang/const-eval/issues/7 for previous discussion.

r? `@oli-obk.`

1 files changed, 6 insertions, 2 deletions

diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 0f6e2e0be52..856ea43b1ff 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -973,12 +973,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 ty::Tuple(_) => stack.extend(ty.tuple_fields().map(|t| (t, depth + 1))),
 
                 ty::Closure(_, substs) => {
-                    stack.extend(substs.as_closure().upvar_tys().map(|t| (t, depth + 1)))
+                    let substs = substs.as_closure();
+                    let ty = self.infcx.shallow_resolve(substs.tupled_upvars_ty());
+                    stack.push((ty, depth + 1));
                 }
 
                 ty::Generator(_, substs, _) => {
                     let substs = substs.as_generator();
-                    stack.extend(substs.upvar_tys().map(|t| (t, depth + 1)));
+                    let ty = self.infcx.shallow_resolve(substs.tupled_upvars_ty());
+
+                    stack.push((ty, depth + 1));
                     stack.push((substs.witness(), depth + 1));
                 }