Erase late bound regions from instance `fn_sig()`

Late bound regions were still part of the signature.

3 files changed, 19 insertions, 7 deletions

diff --git a/compiler/rustc_smir/src/rustc_smir/context.rs b/compiler/rustc_smir/src/rustc_smir/context.rs
index 241a0c22310..5516ca0a599 100644
--- a/compiler/rustc_smir/src/rustc_smir/context.rs
+++ b/compiler/rustc_smir/src/rustc_smir/context.rs
@@ -13,8 +13,8 @@ use stable_mir::mir::mono::{InstanceDef, StaticDef};
 use stable_mir::mir::Body;
 use stable_mir::target::{MachineInfo, MachineSize};
 use stable_mir::ty::{
-    AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, GenericArgs,
-    LineInfo, PolyFnSig, RigidTy, Span, Ty, TyKind, VariantDef,
+    AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, FnSig,
+    GenericArgs, LineInfo, PolyFnSig, RigidTy, Span, Ty, TyKind, VariantDef,
 };
 use stable_mir::{Crate, CrateItem, DefId, Error, Filename, ItemKind, Symbol};
 use std::cell::RefCell;
@@ -324,7 +324,16 @@ impl<'tcx> Context for TablesWrapper<'tcx> {
     fn instance_ty(&self, def: InstanceDef) -> stable_mir::ty::Ty {
         let mut tables = self.0.borrow_mut();
         let instance = tables.instances[def];
-        instance.ty(tables.tcx, ParamEnv::empty()).stable(&mut *tables)
+        instance.ty(tables.tcx, ParamEnv::reveal_all()).stable(&mut *tables)
+    }
+
+    fn instance_sig(&self, def: InstanceDef) -> FnSig {
+        let mut tables = self.0.borrow_mut();
+        let instance = tables.instances[def];
+        let ty = instance.ty(tables.tcx, ParamEnv::reveal_all());
+        let sig = if ty.is_fn() { ty.fn_sig(tables.tcx) } else { instance.args.as_closure().sig() };
+        // Erase late bound regions.
+        tables.tcx.instantiate_bound_regions_with_erased(sig).stable(&mut *tables)
     }
 
     fn instance_def_id(&self, def: InstanceDef) -> stable_mir::DefId {
diff --git a/compiler/stable_mir/src/compiler_interface.rs b/compiler/stable_mir/src/compiler_interface.rs
index 2fac59e71fd..8ee82c24130 100644
--- a/compiler/stable_mir/src/compiler_interface.rs
+++ b/compiler/stable_mir/src/compiler_interface.rs
@@ -10,9 +10,9 @@ use crate::mir::mono::{Instance, InstanceDef, StaticDef};
 use crate::mir::Body;
 use crate::target::MachineInfo;
 use crate::ty::{
-    AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, GenericArgs,
-    GenericPredicates, Generics, ImplDef, ImplTrait, LineInfo, PolyFnSig, RigidTy, Span, TraitDecl,
-    TraitDef, Ty, TyKind, VariantDef,
+    AdtDef, AdtKind, Allocation, ClosureDef, ClosureKind, Const, FieldDef, FnDef, FnSig,
+    GenericArgs, GenericPredicates, Generics, ImplDef, ImplTrait, LineInfo, PolyFnSig, RigidTy,
+    Span, TraitDecl, TraitDef, Ty, TyKind, VariantDef,
 };
 use crate::{
     mir, Crate, CrateItem, CrateItems, DefId, Error, Filename, ImplTraitDecls, ItemKind, Symbol,
@@ -121,6 +121,9 @@ pub trait Context {
     /// Get the instance type with generic substitutions applied and lifetimes erased.
     fn instance_ty(&self, instance: InstanceDef) -> Ty;
 
+    /// Get the instance signature with .
+    fn instance_sig(&self, def: InstanceDef) -> FnSig;
+
     /// Get the instance.
     fn instance_def_id(&self, instance: InstanceDef) -> DefId;
 
diff --git a/compiler/stable_mir/src/mir/mono.rs b/compiler/stable_mir/src/mir/mono.rs
index bc5d4a3b8f4..6b8c69d14ee 100644
--- a/compiler/stable_mir/src/mir/mono.rs
+++ b/compiler/stable_mir/src/mir/mono.rs
@@ -117,7 +117,7 @@ impl Instance {
 
     /// Get this function signature with all types already instantiated.
     pub fn fn_sig(&self) -> FnSig {
-        self.ty().kind().fn_sig().unwrap().skip_binder()
+        with(|cx| cx.instance_sig(self.def))
     }
 
     /// Check whether this instance is an empty shim.