Auto merge of #96883 - jackh726:early-binder-2, r=oli-obk

Add EarlyBinder

Chalk has no concept of `Param` (https://github.com/rust-lang/chalk/blob/e0ade19d139bc784384acc6736cd960c91dd55a1/chalk-ir/src/lib.rs#L579) or `ReEarlyBound` (https://github.com/rust-lang/chalk/blob/e0ade19d139bc784384acc6736cd960c91dd55a1/chalk-ir/src/lib.rs#L1308). Everything  is just "bound" - the equivalent of rustc's late-bound. It's not completely clear yet whether to move everything to the same time of binder in rustc or add `Param` and `ReEarlyBound` in Chalk.

Either way, tracking when we have or haven't already substituted out these in rustc can be helpful.

As a first step, I'm just adding a `EarlyBinder` newtype that is required to call `subst`. I also add a couple "transparent" `bound_*` wrappers around a couple query that are often immediately substituted.

r? `@nikomatsakis`

1 files changed, 4 insertions, 2 deletions

diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index e1e14011e52..dc1946bcdc2 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -9,7 +9,9 @@ use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::print::{Print, Printer};
 use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst};
-use rustc_middle::ty::{self, FloatTy, Instance, IntTy, Ty, TyCtxt, TypeFoldable, UintTy};
+use rustc_middle::ty::{
+    self, EarlyBinder, FloatTy, Instance, IntTy, Ty, TyCtxt, TypeFoldable, UintTy,
+};
 use rustc_span::symbol::kw;
 use rustc_target::abi::call::FnAbi;
 use rustc_target::abi::Integer;
@@ -297,7 +299,7 @@ impl<'tcx> Printer<'tcx> for &mut SymbolMangler<'tcx> {
 
         let mut param_env = self.tcx.param_env_reveal_all_normalized(impl_def_id);
         if !substs.is_empty() {
-            param_env = param_env.subst(self.tcx, substs);
+            param_env = EarlyBinder(param_env).subst(self.tcx, substs);
         }
 
         match &mut impl_trait_ref {