From 5b06898d21661414636e35558821173bf16cbf83 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 19 Oct 2022 05:28:40 +0000
Subject: [PATCH] Check needs_infer before needs_drop in HIR generator analysis

---
 .../drop_ranges/record_consumed_borrow.rs       | 17 +++++++++++------
 .../src/generator_interior/mod.rs               |  4 ++++
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs
index 7954ddc4166..bfe95852aa7 100644
--- a/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs
+++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/record_consumed_borrow.rs
@@ -6,8 +6,11 @@
 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 @@ fn mutate(
 
         // 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));
diff --git a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
index 898419b5b23..45d3e22a213 100644
--- a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
+++ b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs
@@ -382,6 +382,10 @@ fn visit_expr(&mut self, expr: &'tcx Expr<'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)