From 13090889f5b8cbc72b1a14c2cb038dca5727d55c Mon Sep 17 00:00:00 2001
From: Eric Holk <ericholk@microsoft.com>
Date: Fri, 21 Jan 2022 09:36:24 -0800
Subject: [PATCH] Disable drop range tracking in generators

Generator drop tracking caused an ICE for generators involving the Never
type (Issue #93161). Since this breaks miri, we temporarily disable drop
tracking so miri is unblocked while we properly fix the issue.
---
 compiler/rustc_typeck/src/check/generator_interior.rs | 9 ++++++++-
 src/test/ui/async-await/async-fn-nonsend.rs           | 4 ++++
 src/test/ui/async-await/unresolved_type_param.rs      | 4 ++++
 src/test/ui/generator/drop-control-flow.rs            | 4 ++++
 src/test/ui/generator/issue-57478.rs                  | 4 ++++
 src/test/ui/generator/partial-drop.rs                 | 4 ++++
 6 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index 56b6dd9a2844..cb6a49bd0c04 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -22,6 +22,10 @@ use tracing::debug;
 
 mod drop_ranges;
 
+// FIXME(eholk): This flag is here to give a quick way to disable drop tracking in case we find
+// unexpected breakages while it's still new. It should be removed before too long.
+const ENABLE_DROP_TRACKING: bool = false;
+
 struct InteriorVisitor<'a, 'tcx> {
     fcx: &'a FnCtxt<'a, 'tcx>,
     types: FxIndexSet<ty::GeneratorInteriorTypeCause<'tcx>>,
@@ -77,7 +81,10 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
                                 yield_data.expr_and_pat_count, self.expr_count, source_span
                             );
 
-                            if self.drop_ranges.is_dropped_at(hir_id, yield_data.expr_and_pat_count)
+                            if ENABLE_DROP_TRACKING
+                                && self
+                                    .drop_ranges
+                                    .is_dropped_at(hir_id, yield_data.expr_and_pat_count)
                             {
                                 debug!("value is dropped at yield point; not recording");
                                 return false;
diff --git a/src/test/ui/async-await/async-fn-nonsend.rs b/src/test/ui/async-await/async-fn-nonsend.rs
index c5453b67ef5b..a1a05c0acba4 100644
--- a/src/test/ui/async-await/async-fn-nonsend.rs
+++ b/src/test/ui/async-await/async-fn-nonsend.rs
@@ -1,6 +1,10 @@
 // edition:2018
 // compile-flags: --crate-type lib
 
+// FIXME(eholk): temporarily disabled while drop range tracking is disabled
+// (see generator_interior.rs:27)
+// ignore-test
+
 use std::{cell::RefCell, fmt::Debug, rc::Rc};
 
 fn non_sync() -> impl Debug {
diff --git a/src/test/ui/async-await/unresolved_type_param.rs b/src/test/ui/async-await/unresolved_type_param.rs
index d313691b3885..187356ca1402 100644
--- a/src/test/ui/async-await/unresolved_type_param.rs
+++ b/src/test/ui/async-await/unresolved_type_param.rs
@@ -3,6 +3,10 @@
 // (rather than give a general error message)
 // edition:2018
 
+// FIXME(eholk): temporarily disabled while drop range tracking is disabled
+// (see generator_interior.rs:27)
+// ignore-test
+
 async fn bar<T>() -> () {}
 
 async fn foo() {
diff --git a/src/test/ui/generator/drop-control-flow.rs b/src/test/ui/generator/drop-control-flow.rs
index 6319a29f5b7d..8540f7617acd 100644
--- a/src/test/ui/generator/drop-control-flow.rs
+++ b/src/test/ui/generator/drop-control-flow.rs
@@ -1,5 +1,9 @@
 // build-pass
 
+// FIXME(eholk): temporarily disabled while drop range tracking is disabled
+// (see generator_interior.rs:27)
+// ignore-test
+
 // A test to ensure generators capture values that were conditionally dropped,
 // and also that values that are dropped along all paths to a yield do not get
 // included in the generator type.
diff --git a/src/test/ui/generator/issue-57478.rs b/src/test/ui/generator/issue-57478.rs
index 39710febdb95..5c23ecbae327 100644
--- a/src/test/ui/generator/issue-57478.rs
+++ b/src/test/ui/generator/issue-57478.rs
@@ -1,5 +1,9 @@
 // check-pass
 
+// FIXME(eholk): temporarily disabled while drop range tracking is disabled
+// (see generator_interior.rs:27)
+// ignore-test
+
 #![feature(negative_impls, generators)]
 
 struct Foo;
diff --git a/src/test/ui/generator/partial-drop.rs b/src/test/ui/generator/partial-drop.rs
index 36f6e78cb3bf..e89e4b61bbff 100644
--- a/src/test/ui/generator/partial-drop.rs
+++ b/src/test/ui/generator/partial-drop.rs
@@ -1,3 +1,7 @@
+// FIXME(eholk): temporarily disabled while drop range tracking is disabled
+// (see generator_interior.rs:27)
+// ignore-test
+
 #![feature(negative_impls, generators)]
 
 struct Foo;