Do not ICE on closure

Author: JohnTitor

src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs

@@ -240,7 +240,8 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                     let tcx = self.infcx.tcx;
                     let generics = tcx.generics_of(self.mir_def_id);
                     let param = generics.type_param(&param_ty, tcx);
-                    if let Some(generics) = tcx.hir().get_generics(self.mir_def_id) {
+                    if let Some(generics) =
+                        tcx.hir().get_generics(tcx.closure_base_def_id(self.mir_def_id)) {
                         suggest_constraining_type_param(
                             generics,
                             &mut err,

src/test/ui/closures/issue-67123.rs

@@ -0,0 +1,5 @@
+fn foo<T>(t: T) {
+    || { t; t; }; //~ ERROR: use of moved value
+}
+
+fn main() {}

src/test/ui/closures/issue-67123.stderr

@@ -0,0 +1,15 @@
+error[E0382]: use of moved value: `t`
+  --> $DIR/issue-67123.rs:2:13
+   |
+LL | fn foo<T>(t: T) {
+   |        - help: consider restricting this bound: `T: Copy`
+LL |     || { t; t; };
+   |          -  ^ value used here after move
+   |          |
+   |          value moved here
+   |
+   = note: move occurs because `t` has type `T`, which does not implement the `Copy` trait
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0382`.