From 5161b22143bf9a726cfd69d19bef11552d0ed519 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomasz=20Mi=C4=85sko?= <tomasz.miasko@gmail.com>
Date: Tue, 28 Nov 2023 00:00:00 +0000
Subject: [PATCH] Fix coroutine validation for mixed panic strategy

Validation introduced in #113124 allows UnwindAction::Continue and
TerminatorKind::Resume to occur only in functions with ABI that can
unwind. The function ABI depends on the panic strategy, which can vary
across crates.

Usually MIR is built and validated in the same crate. The coroutine drop
glue thus far was an exception. As a result validation could fail when
mixing different panic strategies.

Avoid the problem by executing AbortUnwindingCalls along with the
validation.
---
 compiler/rustc_mir_transform/src/coroutine.rs | 10 ----------
 compiler/rustc_mir_transform/src/shim.rs      |  6 ++++--
 tests/ui/coroutine/auxiliary/unwind-aux.rs    | 11 +++++++++++
 tests/ui/coroutine/unwind-abort-mix.rs        | 13 +++++++++++++
 4 files changed, 28 insertions(+), 12 deletions(-)
 create mode 100644 tests/ui/coroutine/auxiliary/unwind-aux.rs
 create mode 100644 tests/ui/coroutine/unwind-abort-mix.rs

diff --git a/compiler/rustc_mir_transform/src/coroutine.rs b/compiler/rustc_mir_transform/src/coroutine.rs
index 1cb1a9886a09d..d626fed32757d 100644
--- a/compiler/rustc_mir_transform/src/coroutine.rs
+++ b/compiler/rustc_mir_transform/src/coroutine.rs
@@ -51,7 +51,6 @@
 //! Otherwise it drops all the values in scope at the last suspension point.
 
 use crate::abort_unwinding_calls;
-use crate::add_call_guards;
 use crate::deref_separator::deref_finder;
 use crate::errors;
 use crate::pass_manager as pm;
@@ -1168,18 +1167,9 @@ fn create_coroutine_drop_shim<'tcx>(
     simplify::remove_dead_blocks(&mut body);
 
     // Update the body's def to become the drop glue.
-    // This needs to be updated before the AbortUnwindingCalls pass.
     let coroutine_instance = body.source.instance;
     let drop_in_place = tcx.require_lang_item(LangItem::DropInPlace, None);
     let drop_instance = InstanceDef::DropGlue(drop_in_place, Some(coroutine_ty));
-    body.source.instance = drop_instance;
-
-    pm::run_passes_no_validate(
-        tcx,
-        &mut body,
-        &[&abort_unwinding_calls::AbortUnwindingCalls, &add_call_guards::CriticalCallEdges],
-        None,
-    );
 
     // Temporary change MirSource to coroutine's instance so that dump_mir produces more sensible
     // filename.
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index f24a2d07e4949..fba73d5195b76 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -74,11 +74,13 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceDef<'tcx>) -> Body<'
                 let mut body = EarlyBinder::bind(body.clone()).instantiate(tcx, args);
                 debug!("make_shim({:?}) = {:?}", instance, body);
 
-                // Run empty passes to mark phase change and perform validation.
                 pm::run_passes(
                     tcx,
                     &mut body,
-                    &[],
+                    &[
+                        &abort_unwinding_calls::AbortUnwindingCalls,
+                        &add_call_guards::CriticalCallEdges,
+                    ],
                     Some(MirPhase::Runtime(RuntimePhase::Optimized)),
                 );
 
diff --git a/tests/ui/coroutine/auxiliary/unwind-aux.rs b/tests/ui/coroutine/auxiliary/unwind-aux.rs
new file mode 100644
index 0000000000000..215d676911633
--- /dev/null
+++ b/tests/ui/coroutine/auxiliary/unwind-aux.rs
@@ -0,0 +1,11 @@
+// compile-flags: -Cpanic=unwind  --crate-type=lib
+// no-prefer-dynamic
+// edition:2021
+
+#![feature(coroutines)]
+pub fn run<T>(a: T) {
+    let _ = move || {
+        drop(a);
+        yield;
+    };
+}
diff --git a/tests/ui/coroutine/unwind-abort-mix.rs b/tests/ui/coroutine/unwind-abort-mix.rs
new file mode 100644
index 0000000000000..869b3e4f43347
--- /dev/null
+++ b/tests/ui/coroutine/unwind-abort-mix.rs
@@ -0,0 +1,13 @@
+// Ensure that coroutine drop glue is valid when mixing different panic
+// strategies. Regression test for #116953.
+//
+// no-prefer-dynamic
+// build-pass
+// aux-build:unwind-aux.rs
+// compile-flags: -Cpanic=abort
+// needs-unwind
+extern crate unwind_aux;
+
+pub fn main() {
+    unwind_aux::run(String::new());
+}