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.

Author: eholk

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;

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 {

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() {

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.

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;

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;