Don't look for late bound vars if the closure has no input.

Author: lenko-d

compiler/rustc_hir_typeck/src/closure.rs

@@ -12,7 +12,7 @@ use rustc_infer::infer::{InferOk, InferResult};
 use rustc_macros::{TypeFoldable, TypeVisitable};
 use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::visit::{TypeVisitable, TypeVisitableExt};
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor};
+use rustc_middle::ty::{self, List, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::source_map::Span;
 use rustc_span::sym;
@@ -622,7 +622,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         debug!(?body.generator_kind);
 
         let hir_id = self.tcx.hir().local_def_id_to_hir_id(expr_def_id);
-        let bound_vars = self.tcx.late_bound_vars(hir_id);
+        let bound_vars = match decl.inputs.len() {
+            0 => List::empty(),
+            _ => self.tcx.late_bound_vars(hir_id),
+        };
 
         // First, convert the types that the user supplied (if any).
         let supplied_arguments = decl.inputs.iter().map(|a| astconv.ast_ty_to_ty(a));

tests/ui/closures/issue-112547.rs

@@ -0,0 +1,15 @@
+#![feature(non_lifetime_binders)]
+        //~^ WARNING the feature `non_lifetime_binders` is incomplete and may not be safe to use and/or cause compiler crashes
+
+pub fn bar()
+where
+    for<const N: usize = {
+    (||1usize)()
+}> V: IntoIterator
+//~^ ERROR cannot find type `V` in this scope [E0412]
+{
+}
+
+fn main() {
+    bar();
+}

tests/ui/closures/issue-112547.stderr

@@ -0,0 +1,23 @@
+error[E0412]: cannot find type `V` in this scope
+  --> $DIR/issue-112547.rs:8:4
+   |
+LL | }> V: IntoIterator
+   |    ^ not found in this scope
+   |
+help: you might be missing a type parameter
+   |
+LL | pub fn bar<V>()
+   |           +++
+
+warning: the feature `non_lifetime_binders` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/issue-112547.rs:1:12
+   |
+LL | #![feature(non_lifetime_binders)]
+   |            ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0412`.