From 66e718525b7668367a5a8505edc0ba333d314f17 Mon Sep 17 00:00:00 2001
From: Erik Eckstein <eeckstein@apple.com>
Date: Mon, 13 Oct 2025 19:23:14 +0200
Subject: [PATCH] SILCombine: don't fold `unchecked_take_enum_data_addr` -
 `destroy_addr` of enums with deinit

Destroying whole non-copyable enums with a deinit would wrongly trigger calling its deinit.
---
 .../SILCombiner/SILCombinerMiscVisitors.cpp   |  4 +++
 test/SILOptimizer/sil_combine_moveonly.sil    | 26 +++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp b/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
index e5cf557d72a..a58e475082a 100644
--- a/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
+++ b/lib/SILOptimizer/SILCombiner/SILCombinerMiscVisitors.cpp
@@ -1146,6 +1146,10 @@ SILInstruction *SILCombiner::visitUncheckedTakeEnumDataAddrInst(
   }
 
   if (onlyDestroys) {
+    // Destroying whole non-copyable enums with a deinit would wrongly trigger calling its deinit.
+    if (tedai->getOperand()->getType().isValueTypeWithDeinit())
+      return nullptr;
+
     // The unchecked_take_enum_data_addr is dead: remove it and replace all
     // destroys with a destroy of its operand.
     while (!tedai->use_empty()) {
diff --git a/test/SILOptimizer/sil_combine_moveonly.sil b/test/SILOptimizer/sil_combine_moveonly.sil
index df42158c3c1..1a39bc99847 100644
--- a/test/SILOptimizer/sil_combine_moveonly.sil
+++ b/test/SILOptimizer/sil_combine_moveonly.sil
@@ -185,3 +185,29 @@ bb0(%0 : @owned $S2):
   return %r
 }
 
+// CHECK-LABEL: sil [ossa] @dont_fold_destroy_of_take_enum_with_deinit_ossa :
+// CHECK:       bb0(%0 : $*MaybeFileDescriptor):
+// CHECK-NEXT:    %1 = unchecked_take_enum_data_addr %0
+// CHECK-NEXT:    destroy_addr %1
+// CHECK:       } // end sil function 'dont_fold_destroy_of_take_enum_with_deinit_ossa'
+sil [ossa] @dont_fold_destroy_of_take_enum_with_deinit_ossa : $@convention(thin) (@in MaybeFileDescriptor) -> () {
+bb0(%0 : $*MaybeFileDescriptor):
+  %1 = unchecked_take_enum_data_addr %0, #MaybeFileDescriptor.some!enumelt
+  destroy_addr %1
+  %r = tuple ()
+  return %r : $()
+}
+
+// CHECK-LABEL: sil @dont_fold_destroy_of_take_enum_with_deinit :
+// CHECK:       bb0(%0 : $*MaybeFileDescriptor):
+// CHECK-NEXT:    %1 = unchecked_take_enum_data_addr %0
+// CHECK-NEXT:    destroy_addr %1
+// CHECK:       } // end sil function 'dont_fold_destroy_of_take_enum_with_deinit'
+sil @dont_fold_destroy_of_take_enum_with_deinit : $@convention(thin) (@in MaybeFileDescriptor) -> () {
+bb0(%0 : $*MaybeFileDescriptor):
+  %1 = unchecked_take_enum_data_addr %0, #MaybeFileDescriptor.some!enumelt
+  destroy_addr %1
+  %r = tuple ()
+  return %r : $()
+}
+