Check needs_infer before needs_drop in HIR generator analysis

compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs

@@ -6,8 +6,11 @@ use crate::{
 use hir::{def_id::DefId, Body, HirId, HirIdMap};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
-use rustc_middle::hir::place::{PlaceBase, Projection, ProjectionKind};
 use rustc_middle::ty::{ParamEnv, TyCtxt};
+use rustc_middle::{
+    hir::place::{PlaceBase, Projection, ProjectionKind},
+    ty::TypeVisitable,
+};
 
 pub(super) fn find_consumed_and_borrowed<'a, 'tcx>(
     fcx: &'a FnCtxt<'a, 'tcx>,
@@ -198,11 +201,13 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
 
         // If the type being assigned needs dropped, then the mutation counts as a borrow
         // since it is essentially doing `Drop::drop(&mut x); x = new_value;`.
-        //
-        // FIXME(drop-tracking): We need to be more responsible about inference
-        // variables here, since `needs_drop` is a "raw" type query, i.e. it
-        // basically requires types to have been fully resolved.
-        if assignee_place.place.base_ty.needs_drop(self.tcx, self.param_env) {
+        let ty = self.tcx.erase_regions(assignee_place.place.base_ty);
+        if ty.needs_infer() {
+            self.tcx.sess.delay_span_bug(
+                self.tcx.hir().span(assignee_place.hir_id),
+                &format!("inference variables in {ty}"),
+            );
+        } else if ty.needs_drop(self.tcx, self.param_env) {
             self.places
                 .borrowed
                 .insert(TrackedValue::from_place_with_projections_allowed(assignee_place));

compiler/rustc_hir_typeck/src/generator_interior/mod.rs

@@ -382,6 +382,10 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
             let ty = self.fcx.resolve_vars_if_possible(ty);
             let ty = self.fcx.tcx.erase_regions(ty);
             if ty.needs_infer() {
+                self.fcx
+                    .tcx
+                    .sess
+                    .delay_span_bug(expr.span, &format!("inference variables in {ty}"));
                 return true;
             }
             ty.needs_drop(self.fcx.tcx, self.fcx.param_env)