Move-only-check the result of modify coroutines.

lib/SILGen/SILGenApply.cpp

@@ -4913,6 +4913,10 @@ SILGenFunction::emitBeginApply(SILLocation loc, ManagedValue fn,
     auto value = yieldValues[i];
     auto info = yieldInfos[i];
     if (info.isIndirectInOut()) {
+      if (value->getType().isMoveOnly()) {
+        value = B.createMarkUnresolvedNonCopyableValueInst(loc, value,
+         MarkUnresolvedNonCopyableValueInst::CheckKind::ConsumableAndAssignable);
+      }
       yields.push_back(ManagedValue::forLValue(value));
     } else if (info.isConsumed()) {
       if (value->getType().isMoveOnly()) {

lib/SILOptimizer/Mandatory/MoveOnlyAddressCheckerUtils.cpp

@@ -402,6 +402,9 @@ static bool isInOutDefThatNeedsEndOfFunctionLiveness(
         return true;
       }
     }
+    if (auto bai = dyn_cast_or_null<BeginApplyInst>(operand->getDefiningInstruction())) {
+      return true;
+    }
   }
 
   return false;

test/Interpreter/moveonly_read_modify_coroutines.swift

@@ -0,0 +1,36 @@
+// RUN: %target-run-simple-swift | %FileCheck %s
+// REQUIRES: executable_test
+
+struct NC: ~Copyable {
+  deinit { print("destroy") }
+}
+
+class C {
+  private var _data: NC = NC()
+
+  var data: NC {
+    _read { yield _data }
+    _modify { yield &_data }
+  }
+}
+
+func borrow(_ nc: borrowing NC) {}
+func mod(_ nc: inout NC) {}
+
+defer {
+    // CHECK: starting
+    print("starting")
+    do {
+        // CHECK-NEXT: destroy
+        test(C())
+    }
+    // CHECK: done
+    print("done")
+}
+func test(_ c: C) {
+  borrow(c.data)
+  borrow(c.data)
+
+  mod(&c.data)
+  mod(&c.data)
+}