Auto merge of #92805 - BoxyUwU:revert-lazy-anon-const-substs, r=lcnr

partially revertish `lazily "compute" anon const default substs`

reverts #87280 except for some of the changes around `ty::Unevaluated` having a visitor and a generic for promoted
why revert: <https://github.com/rust-lang/rust/pull/92805#issuecomment-1010736049>

r? `@lcnr`

3 files changed, 9 insertions, 14 deletions

diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
index 1daade8f400..b7665d149e4 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs
@@ -347,7 +347,7 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
     fn check_local_or_return_ty(&mut self, ty: Ty<'tcx>, local: Local) {
         let kind = self.body.local_kind(local);
 
-        for ty in ty.walk(self.tcx) {
+        for ty in ty.walk() {
             let ty = match ty.unpack() {
                 GenericArgKind::Type(ty) => ty,
 
diff --git a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
index a3664493e18..cf939aaa73f 100644
--- a/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/transform/check_consts/qualifs.rs
@@ -337,7 +337,7 @@ where
 
     // Check the qualifs of the value of `const` items.
     if let Some(ct) = constant.literal.const_for_ty() {
-        if let ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs_: _, promoted }) = ct.val {
+        if let ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs: _, promoted }) = ct.val {
             // Use qualifs of the type for the promoted. Promoteds in MIR body should be possible
             // only for `NeedsNonConstDrop` with precise drop checking. This is the only const
             // check performed after the promotion. Verify that with an assertion.
diff --git a/compiler/rustc_const_eval/src/transform/promote_consts.rs b/compiler/rustc_const_eval/src/transform/promote_consts.rs
index 55fba5d7ddf..ac282a5ecc8 100644
--- a/compiler/rustc_const_eval/src/transform/promote_consts.rs
+++ b/compiler/rustc_const_eval/src/transform/promote_consts.rs
@@ -843,17 +843,13 @@ impl<'a, 'tcx> Promoter<'a, 'tcx> {
                             ty,
                             val: ty::ConstKind::Unevaluated(ty::Unevaluated {
                                 def,
-                                substs_: Some(InternalSubsts::for_item(
-                                    tcx,
-                                    def.did,
-                                    |param, _| {
-                                        if let ty::GenericParamDefKind::Lifetime = param.kind {
-                                            tcx.lifetimes.re_erased.into()
-                                        } else {
-                                            tcx.mk_param_from_def(param)
-                                        }
-                                    },
-                                )),
+                                substs: InternalSubsts::for_item(tcx, def.did, |param, _| {
+                                    if let ty::GenericParamDefKind::Lifetime = param.kind {
+                                        tcx.lifetimes.re_erased.into()
+                                    } else {
+                                        tcx.mk_param_from_def(param)
+                                    }
+                                }),
                                 promoted: Some(promoted_id),
                             }),
                         })
@@ -969,7 +965,6 @@ pub fn promote_candidates<'tcx>(
         scope.parent_scope = None;
 
         let promoted = Body::new(
-            tcx,
             body.source, // `promoted` gets filled in below
             IndexVec::new(),
             IndexVec::from_elem_n(scope, 1),