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`

2 files changed, 3 insertions, 3 deletions

diff --git a/src/tools/clippy/clippy_utils/src/consts.rs b/src/tools/clippy/clippy_utils/src/consts.rs
index fdb822c3e5b..a80c7ee4929 100644
--- a/src/tools/clippy/clippy_utils/src/consts.rs
+++ b/src/tools/clippy/clippy_utils/src/consts.rs
@@ -9,7 +9,7 @@ use rustc_hir::{BinOp, BinOpKind, Block, Expr, ExprKind, HirId, Item, ItemKind,
 use rustc_lint::LateContext;
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::ty::subst::{Subst, SubstsRef};
-use rustc_middle::ty::{self, FloatTy, ScalarInt, Ty, TyCtxt};
+use rustc_middle::ty::{self, EarlyBinder, FloatTy, ScalarInt, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::Symbol;
 use std::cmp::Ordering::{self, Equal};
@@ -420,7 +420,7 @@ impl<'a, 'tcx> ConstEvalLateContext<'a, 'tcx> {
                 let substs = if self.substs.is_empty() {
                     substs
                 } else {
-                    substs.subst(self.lcx.tcx, self.substs)
+                    EarlyBinder(substs).subst(self.lcx.tcx, self.substs)
                 };
 
                 let result = self
diff --git a/src/tools/clippy/clippy_utils/src/ty.rs b/src/tools/clippy/clippy_utils/src/ty.rs
index 7f14a306d0e..b09eb8c6cd1 100644
--- a/src/tools/clippy/clippy_utils/src/ty.rs
+++ b/src/tools/clippy/clippy_utils/src/ty.rs
@@ -520,7 +520,7 @@ pub fn expr_sig<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) -> Option<ExprFnS
         let ty = cx.typeck_results().expr_ty_adjusted(expr).peel_refs();
         match *ty.kind() {
             ty::Closure(_, subs) => Some(ExprFnSig::Closure(subs.as_closure().sig())),
-            ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.fn_sig(id).subst(cx.tcx, subs))),
+            ty::FnDef(id, subs) => Some(ExprFnSig::Sig(cx.tcx.bound_fn_sig(id).subst(cx.tcx, subs))),
             ty::FnPtr(sig) => Some(ExprFnSig::Sig(sig)),
             ty::Dynamic(bounds, _) => {
                 let lang_items = cx.tcx.lang_items();