Review comments

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -718,11 +718,10 @@ fn get_rust_try_fn<'ll, 'tcx>(
         hir::Unsafety::Unsafe,
         Abi::Rust,
     )));
-    let output = tcx.types.i32;
+    // `unsafe fn(unsafe fn(*mut i8) -> (), *mut i8, unsafe fn(*mut i8, *mut i8) -> ()) -> i32`
-    // `unsafe fn(unsafe fn(*mut i8) -> (), unsafe fn(*mut i8, *mut i8) -> ()) -> i32`
     let rust_fn_sig = ty::Binder::dummy(cx.tcx.mk_fn_sig(
         vec![try_fn_ty, i8p, catch_fn_ty].into_iter(),
-        output,
+        tcx.types.i32,
         false,
         hir::Unsafety::Unsafe,
         Abi::Rust,

compiler/rustc_middle/src/ty/mod.rs

@@ -1056,9 +1056,21 @@ impl<'tcx> Predicate<'tcx> {
         }
     }
 
+    /// Converts this to a `Binder<PredicateAtom<'tcx>>`. If the value was an
+    /// `Atom`, then it is not allowed to contain escaping bound vars.
+    pub fn bound_atom(self, _tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> {
+        match self.kind() {
+            &PredicateKind::ForAll(binder) => binder,
+            &PredicateKind::Atom(atom) => {
+                assert!(!atom.has_escaping_bound_vars());
+                Binder::dummy(atom)
+            }
+        }
+    }
+
     /// Allows using a `Binder<PredicateAtom<'tcx>>` even if the given predicate previously
     /// contained unbound variables by shifting these variables outwards.
-    pub fn bound_atom(self, tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> {
+    pub fn bound_atom_with_opt_escaping(self, tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> {
         match self.kind() {
             &PredicateKind::ForAll(binder) => binder,
             &PredicateKind::Atom(atom) => Binder::wrap_nonbinding(tcx, atom),

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -618,7 +618,7 @@ pub trait PrettyPrinter<'tcx>:
                         // may contain unbound variables. We therefore do this manually.
                         //
                         // FIXME(lcnr): Find out why exactly this is the case :)
-                        let bound_predicate = predicate.bound_atom(self.tcx());
+                        let bound_predicate = predicate.bound_atom_with_opt_escaping(self.tcx());
                         if let ty::PredicateAtom::Trait(pred, _) = bound_predicate.skip_binder() {
                             let trait_ref = bound_predicate.map_bound(|_| pred.trait_ref);
                             // Don't print +Sized, but rather +?Sized if absent.

compiler/rustc_traits/src/chalk/lowering.rs

@@ -81,8 +81,11 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'
         interner: &RustInterner<'tcx>,
     ) -> chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'tcx>>> {
         let clauses = self.environment.into_iter().map(|predicate| {
-            let (predicate, binders, _named_regions) =
+            let (predicate, binders, _named_regions) = collect_bound_vars(
-                collect_bound_vars(interner, interner.tcx, &predicate.bound_atom(interner.tcx));
+                interner,
+                interner.tcx,
+                &predicate.bound_atom_with_opt_escaping(interner.tcx),
+            );
             let consequence = match predicate {
                 ty::PredicateAtom::TypeWellFormedFromEnv(ty) => {
                     chalk_ir::DomainGoal::FromEnv(chalk_ir::FromEnv::Ty(ty.lower_into(interner)))
@@ -133,8 +136,11 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::InEnvironment<chalk_ir::Goal<RustInterner<'
 
 impl<'tcx> LowerInto<'tcx, chalk_ir::GoalData<RustInterner<'tcx>>> for ty::Predicate<'tcx> {
     fn lower_into(self, interner: &RustInterner<'tcx>) -> chalk_ir::GoalData<RustInterner<'tcx>> {
-        let (predicate, binders, _named_regions) =
+        let (predicate, binders, _named_regions) = collect_bound_vars(
-            collect_bound_vars(interner, interner.tcx, &self.bound_atom(interner.tcx));
+            interner,
+            interner.tcx,
+            &self.bound_atom_with_opt_escaping(interner.tcx),
+        );
 
         let value = match predicate {
             ty::PredicateAtom::Trait(predicate, _) => {
@@ -653,8 +659,11 @@ impl<'tcx> LowerInto<'tcx, Option<chalk_ir::QuantifiedWhereClause<RustInterner<'
         self,
         interner: &RustInterner<'tcx>,
     ) -> Option<chalk_ir::QuantifiedWhereClause<RustInterner<'tcx>>> {
-        let (predicate, binders, _named_regions) =
+        let (predicate, binders, _named_regions) = collect_bound_vars(
-            collect_bound_vars(interner, interner.tcx, &self.bound_atom(interner.tcx));
+            interner,
+            interner.tcx,
+            &self.bound_atom_with_opt_escaping(interner.tcx),
+        );
         let value = match predicate {
             ty::PredicateAtom::Trait(predicate, _) => {
                 Some(chalk_ir::WhereClause::Implemented(predicate.trait_ref.lower_into(interner)))
@@ -762,8 +771,11 @@ impl<'tcx> LowerInto<'tcx, Option<chalk_solve::rust_ir::QuantifiedInlineBound<Ru
         self,
         interner: &RustInterner<'tcx>,
     ) -> Option<chalk_solve::rust_ir::QuantifiedInlineBound<RustInterner<'tcx>>> {
-        let (predicate, binders, _named_regions) =
+        let (predicate, binders, _named_regions) = collect_bound_vars(
-            collect_bound_vars(interner, interner.tcx, &self.bound_atom(interner.tcx));
+            interner,
+            interner.tcx,
+            &self.bound_atom_with_opt_escaping(interner.tcx),
+        );
         match predicate {
             ty::PredicateAtom::Trait(predicate, _) => Some(chalk_ir::Binders::new(
                 binders,