Merge pull request #12717 from compnerd/dealloc_box

IRGen: properly handle deallocation of a boxed type

Author: compnerd

lib/IRGen/GenHeap.cpp

@@ -1541,6 +1541,7 @@ class FixedBoxTypeInfoBase : public BoxTypeInfo {
     auto size = layout.emitSize(IGF.IGM);
     auto alignMask = layout.emitAlignMask(IGF.IGM);
 
+    IGF.emitNativeSetDeallocating(box);
     emitDeallocateHeapObject(IGF, box, size, alignMask);
   }
 

test/IRGen/alloc_box.swift

@@ -0,0 +1,15 @@
+// RUN: %target-swift-frontend -primary-file %s -emit-ir -o - | %FileCheck %s
+
+func f() -> Bool? { return nil }
+
+({
+  guard var b = f() else { return }
+  let c = { b = true }
+  _ = (b, c)
+})()
+
+// CHECK-LABEL: @_T09alloc_boxyycfU_
+// CHECK: <label>:8:
+// CHECK: call void @swift_setDeallocating
+// CHECK: call void @swift_rt_swift_deallocObject
+