From a904fee7fe22e02c4bd1a22a6f28768db33997e8 Mon Sep 17 00:00:00 2001
From: Dario Rexin <drexin@apple.com>
Date: Thu, 15 May 2025 10:21:22 -0700
Subject: [PATCH] [IRGen] Don't set HasLayoutString flag on non-copyable
 generic types

rdar://151176697

While generic types generally have layout strings (when enabled), non-copyable types don't, so
we have to make sure the flag does not get set.
---
 lib/IRGen/GenMeta.cpp                         | 28 ++++++++-------
 .../layout_string_witnesses_types.swift       | 20 +++++++++++
 .../layout_string_witnesses_dynamic.swift     | 36 +++++++++++++++++++
 3 files changed, 72 insertions(+), 12 deletions(-)

diff --git a/lib/IRGen/GenMeta.cpp b/lib/IRGen/GenMeta.cpp
index 62facbd61f240..930845118ee46 100644
--- a/lib/IRGen/GenMeta.cpp
+++ b/lib/IRGen/GenMeta.cpp
@@ -6014,12 +6014,14 @@ namespace {
       if (!layoutStringsEnabled(IGM)) {
         return false;
       }
-      return !!getLayoutString() ||
-             (IGM.Context.LangOpts.hasFeature(
-                 Feature::LayoutStringValueWitnessesInstantiation) &&
-              IGM.getOptions().EnableLayoutStringValueWitnessesInstantiation &&
-                    (HasDependentVWT || HasDependentMetadata) &&
-                      !isa<FixedTypeInfo>(IGM.getTypeInfo(getLoweredType())));
+      const auto &TI = IGM.getTypeInfo(getLoweredType());
+      return (!!getLayoutString() ||
+              (IGM.Context.LangOpts.hasFeature(
+                   Feature::LayoutStringValueWitnessesInstantiation) &&
+               IGM.getOptions().EnableLayoutStringValueWitnessesInstantiation &&
+               (HasDependentVWT || HasDependentMetadata) &&
+               !isa<FixedTypeInfo>(TI))) &&
+             TI.isCopyable(ResilienceExpansion::Maximal);
     }
 
     llvm::Constant *emitNominalTypeDescriptor() {
@@ -6547,13 +6549,15 @@ namespace {
       if (!layoutStringsEnabled(IGM)) {
         return false;
       }
+      auto &TI = IGM.getTypeInfo(getLoweredType());
 
-      return !!getLayoutString() ||
-             (IGM.Context.LangOpts.hasFeature(
-                  Feature::LayoutStringValueWitnessesInstantiation) &&
-              IGM.getOptions().EnableLayoutStringValueWitnessesInstantiation &&
-              (HasDependentVWT || HasDependentMetadata) &&
-              !isa<FixedTypeInfo>(IGM.getTypeInfo(getLoweredType())));
+      return (!!getLayoutString() ||
+              (IGM.Context.LangOpts.hasFeature(
+                   Feature::LayoutStringValueWitnessesInstantiation) &&
+               IGM.getOptions().EnableLayoutStringValueWitnessesInstantiation &&
+               (HasDependentVWT || HasDependentMetadata) &&
+               !isa<FixedTypeInfo>(TI))) &&
+             TI.isCopyable(ResilienceExpansion::Maximal);
     }
 
     llvm::Constant *emitNominalTypeDescriptor() {
diff --git a/test/Interpreter/Inputs/layout_string_witnesses_types.swift b/test/Interpreter/Inputs/layout_string_witnesses_types.swift
index 65060bfb66c72..b1bb42bd254fe 100644
--- a/test/Interpreter/Inputs/layout_string_witnesses_types.swift
+++ b/test/Interpreter/Inputs/layout_string_witnesses_types.swift
@@ -673,6 +673,21 @@ public enum MultiPayloadAnyObject {
     case z(AnyObject)
 }
 
+public struct NonCopyableGenericStruct<T>: ~Copyable {
+    let x: Int
+    let y: T
+
+    public init(x: Int, y: T) {
+        self.x = x
+        self.y = y
+    }
+}
+
+public enum NonCopyableGenericEnum<T>: ~Copyable {
+    case x(Int, T?)
+    case y(Int)
+}
+
 @inline(never)
 public func consume<T>(_ x: T.Type) {
     withExtendedLifetime(x) {}
@@ -751,6 +766,11 @@ public func testGenericArrayDestroy<T>(_ buffer: UnsafeMutableBufferPointer<T>)
     buffer.deinitialize()
 }
 
+@inline(never)
+public func testGenericArrayDestroy<T: ~Copyable>(_ buffer: UnsafeMutableBufferPointer<T>) {
+    buffer.deinitialize()
+}
+
 @inline(never)
 public func testGenericArrayInitWithCopy<T>(dest: UnsafeMutableBufferPointer<T>, src: UnsafeMutableBufferPointer<T>) {
     _ = dest.initialize(fromContentsOf: src)
diff --git a/test/Interpreter/layout_string_witnesses_dynamic.swift b/test/Interpreter/layout_string_witnesses_dynamic.swift
index 418ebbabfc064..b91bf03a1a068 100644
--- a/test/Interpreter/layout_string_witnesses_dynamic.swift
+++ b/test/Interpreter/layout_string_witnesses_dynamic.swift
@@ -1239,6 +1239,42 @@ func testGenericResilientWithUnmanagedAndWeak() {
 
 testGenericResilientWithUnmanagedAndWeak()
 
+func testNonCopyableGenericStructSimpleClass() {
+    let ptr = UnsafeMutableBufferPointer<NonCopyableGenericStruct<SimpleClass>>.allocate(capacity: 1)
+
+    let x = NonCopyableGenericStruct(x: 23, y: SimpleClass(x: 23))
+    ptr[0] = x
+
+    // CHECK-NEXT: Before deinit
+    print("Before deinit")
+
+
+    // CHECK-NEXT: SimpleClass deinitialized!
+    testGenericArrayDestroy(ptr)
+
+    ptr.deallocate()
+}
+
+testNonCopyableGenericStructSimpleClass()
+
+func testNonCopyableGenericEnumSimpleClass() {
+    let ptr = UnsafeMutableBufferPointer<NonCopyableGenericEnum<SimpleClass>>.allocate(capacity: 1)
+
+    let x = NonCopyableGenericEnum.x(23, SimpleClass(x: 23))
+    ptr[0] = x
+
+    // CHECK-NEXT: Before deinit
+    print("Before deinit")
+
+
+    // CHECK-NEXT: SimpleClass deinitialized!
+    testGenericArrayDestroy(ptr)
+
+    ptr.deallocate()
+}
+
+testNonCopyableGenericEnumSimpleClass()
+
 #if os(macOS)
 
 import Foundation