Merge pull request #71242 from nate-chandler/bitwise-copyable/not-for-unchecked

[BitwiseCopyable] Don't derive on @unchecked field

Author: nate-chandler

lib/SIL/IR/TypeLowering.cpp

@@ -28,6 +28,7 @@
 #include "swift/AST/Pattern.h"
 #include "swift/AST/PrettyStackTrace.h"
 #include "swift/AST/PropertyWrappers.h"
+#include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/TypeDifferenceVisitor.h"
 #include "swift/AST/Types.h"
 #include "swift/ClangImporter/ClangModule.h"
@@ -3009,6 +3010,21 @@ void TypeConverter::verifyLexicalLowering(const TypeLowering &lowering,
   }
 }
 
+static bool isUnchecked(ProtocolConformanceRef conformance) {
+  if (!conformance)
+    return false;
+  if (!conformance.isConcrete())
+    return false;
+  auto concrete = conformance.getConcrete();
+  assert(concrete);
+  auto *root = concrete->getRootConformance();
+  assert(root);
+  auto *normal = dyn_cast<NormalProtocolConformance>(root);
+  if (!normal)
+    return false;
+  return normal->isUnchecked();
+}
+
 void TypeConverter::verifyTrivialLowering(const TypeLowering &lowering,
                                           AbstractionPattern origType,
                                           CanType substType,
@@ -3042,10 +3058,17 @@ void TypeConverter::verifyTrivialLowering(const TypeLowering &lowering,
           if (!nominal)
             return false;
 
-          // Nominals with generic parameters must be explicitly conformed to
-          // BitwiseCopyable.
-          auto *generic = ty.getAnyGeneric();
-          if (generic && generic->isGenericContext()) {
+          // Don't walk into types whose conformance is unchecked--such
+          // conformances obstruct automatic inference of BitwiseCopyable.
+          auto conformance = M.checkConformance(ty, bitwiseCopyableProtocol);
+          if (isUnchecked(conformance)) {
+            return true;
+          }
+
+          // Nominals with fields that conditionally conform to BitwiseCopyable
+          // must be explicitly conditionally conformed.  Such a field must be a
+          // generic context.
+          if (nominal->isGenericContext()) {
             return true;
           }
 
@@ -3059,10 +3082,12 @@ void TypeConverter::verifyTrivialLowering(const TypeLowering &lowering,
           // Return false to indicate seeing a leaf which justifies the type
           // being trivial but not conforming to BitwiseCopyable.
 
-          // A BitwiseCopyable conformer appearing within its layout doesn't
-          // explain why substType doesn't itself conform.
-          if (M.checkConformance(ty, bitwiseCopyableProtocol))
-            return true;
+          // A BitwiseCopyable conformer appearing within its layout explains a
+          // non-conformance iff the conformance is @unchecked.
+          auto conformance = M.checkConformance(ty, bitwiseCopyableProtocol);
+          if (conformance) {
+            return !isUnchecked(conformance);
+          }
 
           // ModuleTypes are trivial but don't warrant being given a conformance
           // to BitwiseCopyable.
@@ -3099,15 +3124,15 @@ void TypeConverter::verifyTrivialLowering(const TypeLowering &lowering,
             return true;
           }
 
-          /// A non-conforming generic nominal type justifies substType not
-          /// conforming.
-          auto *generic = ty.getAnyGeneric();
-          if (generic && generic->isGenericContext()) {
+          /// A field of conditionally-BitwiseCopyable type justifies the
+          /// aggregate not conforming because the aggregate must be conformed
+          /// explicitly in that case.
+          if (nominal->isGenericContext()) {
             return false;
           }
 
           // The field is trivial and the whole type is nonconforming.  That's
-          // legal iff the type is public.
+          // legal iff the field's type is public.
           return !nominal
                       ->getFormalAccessScope(
                           /*useDC=*/nullptr,
@@ -3148,6 +3173,7 @@ void TypeConverter::verifyTrivialLowering(const TypeLowering &lowering,
       llvm::errs() << "Non-trivial type with _BitwiseCopyable conformance!?:\n"
                    << substType << "\n";
       conformance.print(llvm::errs());
+      llvm::errs() << "\n";
       assert(false);
     }
   }

lib/Sema/TypeCheckBitwise.cpp

@@ -106,6 +106,7 @@ class BitwiseCopyableStorageVisitor : public StorageVisitor {
 
   bool visitMemberDecl(ValueDecl *storage, Type ty);
   bool visitMemberType(Type type, SourceLoc loc);
+  bool isUnchecked(ProtocolConformanceRef conformance);
   bool visitNonconformingMemberType(Type type, SourceLoc loc);
   void emitNonconformingMemberTypeDiagnostic(Type ty, SourceLoc loc);
 };
@@ -136,6 +137,13 @@ bool BitwiseCopyableStorageVisitor::visitMemberType(Type ty, SourceLoc loc) {
     return visitNonconformingMemberType(ty, loc);
   }
 
+  if (isImplicit(check) && isUnchecked(conformance)) {
+    // Do not automatically derive conformance if one of the field's
+    // conformance is @unchecked.
+    invalid = true;
+    return true;
+  }
+
   // Walk the conformance, diagnosing any missing BitwiseCopyable conformances.
   bool anyMissing = false;
   conformance.forEachMissingConformance(
@@ -150,6 +158,20 @@ bool BitwiseCopyableStorageVisitor::visitMemberType(Type ty, SourceLoc loc) {
   return anyMissing;
 }
 
+bool BitwiseCopyableStorageVisitor::isUnchecked(
+    ProtocolConformanceRef conformance) {
+  if (!conformance.isConcrete())
+    return false;
+  auto concrete = conformance.getConcrete();
+  assert(concrete);
+  auto *root = concrete->getRootConformance();
+  assert(root);
+  auto *normal = dyn_cast<NormalProtocolConformance>(root);
+  if (!normal)
+    return false;
+  return normal->isUnchecked();
+}
+
 bool BitwiseCopyableStorageVisitor::visitNonconformingMemberType(
     Type ty, SourceLoc loc) {
   if (ty->hasError())

lib/Sema/TypeCheckProtocol.cpp

@@ -2165,7 +2165,8 @@ static void diagnoseConformanceImpliedByConditionalConformance(
 /// to the given protocol. This should return true when @unchecked can be
 /// used to disable those semantic checks.
 static bool hasAdditionalSemanticChecks(ProtocolDecl *proto) {
-  return proto->isSpecificProtocol(KnownProtocolKind::Sendable);
+  return proto->isSpecificProtocol(KnownProtocolKind::Sendable) ||
+         proto->isSpecificProtocol(KnownProtocolKind::BitwiseCopyable);
 }
 
 /// Determine whether the type \c T conforms to the protocol \c Proto,

stdlib/public/core/BridgeObjectiveC.swift

@@ -407,7 +407,7 @@ public func _getBridgedNonVerbatimObjectiveCType<T>(_: T.Type) -> Any.Type?
 /// already have writeback-scoped lifetime.
 @frozen
 public struct AutoreleasingUnsafeMutablePointer<Pointee /* TODO : class */>
-  :  _Pointer {
+  :  _Pointer, @unchecked _BitwiseCopyable {
 
   public let _rawValue: Builtin.RawPointer
 

stdlib/public/core/CTypes.swift

@@ -142,7 +142,7 @@ public typealias CBool = Bool
 /// Opaque pointers are used to represent C pointers to types that
 /// cannot be represented in Swift, such as incomplete struct types.
 @frozen
-public struct OpaquePointer {
+public struct OpaquePointer : @unchecked _BitwiseCopyable {
   @usableFromInline
   internal var _rawValue: Builtin.RawPointer
 

stdlib/public/core/Integers.swift

@@ -1904,7 +1904,8 @@ public protocol _LosslessStringConvertibleOrNone {}
 /// customization points for arithmetic operations. When you provide just those
 /// methods, the standard library provides default implementations for all
 /// other arithmetic methods and operators.
-public protocol FixedWidthInteger: BinaryInteger, _LosslessStringConvertibleOrNone
+public protocol FixedWidthInteger
+: BinaryInteger, _LosslessStringConvertibleOrNone, _BitwiseCopyable
 where Magnitude: FixedWidthInteger & UnsignedInteger,
       Stride: FixedWidthInteger & SignedInteger {
   /// The number of bits used for the underlying binary representation of

stdlib/public/core/SIMDVector.swift

@@ -80,7 +80,8 @@ public protocol SIMDScalar : _BitwiseCopyable {
 public protocol SIMD<Scalar>:
   SIMDStorage,
   Hashable,
-  ExpressibleByArrayLiteral
+  ExpressibleByArrayLiteral,
+  _BitwiseCopyable
 {
   /// The mask type resulting from pointwise comparisons of this vector type.
   associatedtype MaskStorage: SIMD
@@ -95,7 +96,8 @@ public protocol SIMD<Scalar>:
   Codable,
   Hashable,
   CustomStringConvertible,
-  ExpressibleByArrayLiteral
+  ExpressibleByArrayLiteral,
+  _BitwiseCopyable
 {
   /// The mask type resulting from pointwise comparisons of this vector type.
   associatedtype MaskStorage: SIMD

stdlib/public/core/UnsafeBufferPointer.swift.gyb

@@ -30,7 +30,8 @@
 /// collection with an `${Self}` instance copies the instances out of the
 /// referenced memory and into the new collection.
 @frozen // unsafe-performance
-public struct Unsafe${Mutable}BufferPointer<Element> {
+public struct Unsafe${Mutable}BufferPointer<Element> 
+  : @unchecked _BitwiseCopyable {
 
   @usableFromInline
   let _position: Unsafe${Mutable}Pointer<Element>?

stdlib/public/core/UnsafePointer.swift

@@ -205,7 +205,7 @@
 ///       let numberPointer = UnsafePointer<Int>(&number)
 ///       // Accessing 'numberPointer' is undefined behavior.
 @frozen // unsafe-performance
-public struct UnsafePointer<Pointee>: _Pointer {
+public struct UnsafePointer<Pointee>: _Pointer, @unchecked _BitwiseCopyable {
 
   /// A type that represents the distance between two pointers.
   public typealias Distance = Int
@@ -578,7 +578,8 @@ public struct UnsafePointer<Pointee>: _Pointer {
 ///       let numberPointer = UnsafeMutablePointer<Int>(&number)
 ///       // Accessing 'numberPointer' is undefined behavior.
 @frozen // unsafe-performance
-public struct UnsafeMutablePointer<Pointee>: _Pointer {
+public struct UnsafeMutablePointer<Pointee>
+  : _Pointer, @unchecked _BitwiseCopyable {
 
   /// A type that represents the distance between two pointers.
   public typealias Distance = Int

stdlib/public/core/UnsafeRawPointer.swift

@@ -169,7 +169,7 @@
 ///       let numberPointer = UnsafeRawPointer(&number)
 ///       // Accessing 'numberPointer' is undefined behavior.
 @frozen
-public struct UnsafeRawPointer: _Pointer {
+public struct UnsafeRawPointer: _Pointer, @unchecked _BitwiseCopyable {
 
   public typealias Pointee = UInt8
 
@@ -727,7 +727,7 @@ extension UnsafeRawPointer {
 ///       let numberPointer = UnsafeMutableRawPointer(&number)
 ///       // Accessing 'numberPointer' is undefined behavior.
 @frozen
-public struct UnsafeMutableRawPointer: _Pointer {
+public struct UnsafeMutableRawPointer: _Pointer, @unchecked _BitwiseCopyable {
 
   public typealias Pointee = UInt8