[ownership] Change "AnyForwardingInst" with trivial return type to return OwnershipKind::None even if they forward non-OwnershipKind::none ownership.

Otherwise the forwarding instruction will return a trivial value with
non-OwnershipKind::None ownership. This inevitably causes an ownership violation
since any place that we use that trivial value will expect the value to have
OwnershipKind::None, showing the inconsistency that this problem yields.

Author: gottesmm

lib/SIL/IR/ValueOwnership.cpp

@@ -241,7 +241,9 @@ ValueOwnershipKindClassifier::visitForwardingInst(SILInstruction *i,
 #define FORWARDING_OWNERSHIP_INST(INST)                                        \
   ValueOwnershipKind ValueOwnershipKindClassifier::visit##INST##Inst(          \
       INST##Inst *I) {                                                         \
-    return I->getForwardingOwnershipKind();                                    \
+    return I->getType().isTrivial(*I->getFunction())                           \
+               ? ValueOwnershipKind(OwnershipKind::None)                       \
+               : I->getForwardingOwnershipKind();                              \
   }
 FORWARDING_OWNERSHIP_INST(BridgeObjectToRef)
 FORWARDING_OWNERSHIP_INST(ConvertFunction)

test/SIL/ownership-verifier/use_verifier.sil

@@ -1431,3 +1431,30 @@ bb0(%0 : @guaranteed $Builtin.NativeObject):
   %2 = unmanaged_to_ref %1 : $@sil_unmanaged Builtin.NativeObject to $Builtin.NativeObject
   return %2 : $Builtin.NativeObject
 }
+
+sil [ossa] @nontrivial_enum_unchecked_enum_data_trivial_payload_owned : $@convention(thin) (@owned ThreeDifferingPayloadEnum) -> Builtin.Int32 {
+bb0(%0 : @owned $ThreeDifferingPayloadEnum):
+  // NOTE: It may be surprising that %0 is consumed by this unchecked_enum_data
+  // despite the result of the instruction being trivial... after all... aren't
+  // we leaking something?! If one takes a step back, one will realize that even
+  // though %0 is statically owned, it dynamically is known to be a value with
+  // OwnershipKind::None and thus there is nothing to clean up. So in a certain
+  // sense by converting its non-trivial input type to a trivial output type,
+  // the instruction is stating that it knows that %0 is really dynamically
+  // OwnershipKind::None and thus it is safe to not propagate a value with
+  // non-OwnershipKind::None to be cleaned up to cleanup %0.
+  %1 = unchecked_enum_data %0 : $ThreeDifferingPayloadEnum, #ThreeDifferingPayloadEnum.trivial_payload!enumelt
+  return %1 : $Builtin.Int32
+}
+
+sil [ossa] @nontrivial_enum_unchecked_enum_data_trivial_payload_guaranteed : $@convention(thin) (@guaranteed ThreeDifferingPayloadEnum) -> Builtin.Int32 {
+bb0(%0 : @guaranteed $ThreeDifferingPayloadEnum):
+  %1 = unchecked_enum_data %0 : $ThreeDifferingPayloadEnum, #ThreeDifferingPayloadEnum.trivial_payload!enumelt
+  return %1 : $Builtin.Int32
+}
+
+sil [ossa] @nontrivial_enum_unchecked_enum_data_trivial_payload_unowned : $@convention(thin) (ThreeDifferingPayloadEnum) -> Builtin.Int32 {
+bb0(%0 : @unowned $ThreeDifferingPayloadEnum):
+  %1 = unchecked_enum_data %0 : $ThreeDifferingPayloadEnum, #ThreeDifferingPayloadEnum.trivial_payload!enumelt
+  return %1 : $Builtin.Int32
+}