[Safe mode] Diagnose uses of declarations involving unsafe types

DougGregor · DougGregor · commit 39f1e97bf99e · 2024-08-19T14:33:09.000-07:00
When referencing a declaration, check whether any of the types in that
reference are unsafe. This can diagnose cases where the original
declaration either wasn't actually unsafe, or is being provided with
unsafe types via generics.
diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
@@ -7974,6 +7974,9 @@ ERROR(override_safe_withunsafe,none,
 ERROR(witness_unsafe,none,
      "unsafe %0 %1 cannot satisfy safe requirement",
       (DescriptiveDeclKind, DeclName))
+ERROR(type_witness_unsafe,none,
+      "unsafe type %0 cannot satisfy safe associated type %1",
+      (Type, DeclName))
 ERROR(unchecked_conformance_is_unsafe,none,
       "@unchecked conformance involves unsafe code", ())
 ERROR(unowned_unsafe_is_unsafe,none,
@@ -7983,6 +7986,11 @@ ERROR(nonisolated_unsafe_is_unsafe,none,
 ERROR(reference_to_unsafe_decl,none,
       "%select{reference|call}0 to unsafe %kindbase1",
       (bool, const ValueDecl *))
+ERROR(reference_to_unsafe_typed_decl,none,
+      "%select{reference|call}0 to %kindbase1 involves unsafe type %2",
+      (bool, const ValueDecl *, Type))
+NOTE(unsafe_decl_here,none,
+     "unsafe %kindbase0 declared here", (const ValueDecl *))
 
 #define UNDEFINE_DIAGNOSTIC_MACROS
 #include "DefineDiagnosticMacros.h"
diff --git a/include/swift/AST/Types.h b/include/swift/AST/Types.h
@@ -185,7 +185,10 @@ class RecursiveTypeProperties {
     /// Contains a PackArchetypeType. Also implies HasPrimaryArchetype.
     HasPackArchetype = 0x20000,
 
-    Last_Property = HasPackArchetype
+    /// Whether this type contains an unsafe type.
+    IsUnsafe = 0x040000,
+
+    Last_Property = IsUnsafe
   };
   enum { BitWidth = countBitsUsed(Property::Last_Property) };
 
@@ -266,6 +269,8 @@ class RecursiveTypeProperties {
 
   bool hasPackArchetype() const { return Bits & HasPackArchetype; }
 
+  bool isUnsafe() const { return Bits & IsUnsafe; }
+
   /// Does a type with these properties structurally contain a
   /// parameterized existential type?
   bool hasParameterizedExistential() const {
@@ -431,12 +436,12 @@ class alignas(1 << TypeAlignInBits) TypeBase
     NumProtocols : 16
   );
 
-  SWIFT_INLINE_BITFIELD_FULL(TypeVariableType, TypeBase, 7+29,
+  SWIFT_INLINE_BITFIELD_FULL(TypeVariableType, TypeBase, 7+28,
     /// Type variable options.
     Options : 7,
     : NumPadBits,
     /// The unique number assigned to this type variable.
-    ID : 29
+    ID : 28
   );
 
   SWIFT_INLINE_BITFIELD_FULL(ErrorUnionType, TypeBase, 32,
@@ -709,6 +714,11 @@ class alignas(1 << TypeAlignInBits) TypeBase
     return getRecursiveProperties().hasPackArchetype();
   }
 
+  /// Whether the type contains an @unsafe type in it anywhere.
+  bool isUnsafe() const {
+    return getRecursiveProperties().isUnsafe();
+  }
+
   /// Determine whether the type involves a primary, pack or local archetype.
   ///
   /// FIXME: Replace all remaining callers with a more precise check.
@@ -6637,7 +6647,8 @@ class PrimaryArchetypeType final : public ArchetypeType,
                        GenericEnvironment *GenericEnv,
                        Type InterfaceType,
                        ArrayRef<ProtocolDecl *> ConformsTo,
-                       Type Superclass, LayoutConstraint Layout);
+                       Type Superclass, LayoutConstraint Layout,
+                       RecursiveTypeProperties Properties);
 };
 BEGIN_CAN_TYPE_WRAPPER(PrimaryArchetypeType, ArchetypeType)
 END_CAN_TYPE_WRAPPER(PrimaryArchetypeType, ArchetypeType)
@@ -6918,7 +6929,8 @@ class PackArchetypeType final
 private:
   PackArchetypeType(const ASTContext &Ctx, GenericEnvironment *GenericEnv,
                     Type InterfaceType, ArrayRef<ProtocolDecl *> ConformsTo,
-                    Type Superclass, LayoutConstraint Layout, PackShape Shape);
+                    Type Superclass, LayoutConstraint Layout, PackShape Shape,
+                    RecursiveTypeProperties properties);
 };
 BEGIN_CAN_TYPE_WRAPPER(PackArchetypeType, ArchetypeType)
 END_CAN_TYPE_WRAPPER(PackArchetypeType, ArchetypeType)
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
@@ -3897,7 +3897,9 @@ get(GenericTypeDecl *TheDecl, Type Parent, const ASTContext &C) {
   UnboundGenericType::Profile(ID, TheDecl, Parent);
   void *InsertPos = nullptr;
   RecursiveTypeProperties properties;
+  if (TheDecl->isUnsafe()) properties |= RecursiveTypeProperties::IsUnsafe;
   if (Parent) properties |= Parent->getRecursiveProperties();
+
   auto arena = getArena(properties);
 
   if (auto unbound = C.getImpl().getArena(arena).UnboundGenericTypes
@@ -3948,6 +3950,7 @@ BoundGenericType *BoundGenericType::get(NominalTypeDecl *TheDecl,
   llvm::FoldingSetNodeID ID;
   BoundGenericType::Profile(ID, TheDecl, Parent, GenericArgs);
   RecursiveTypeProperties properties;
+  if (TheDecl->isUnsafe()) properties |= RecursiveTypeProperties::IsUnsafe;
   if (Parent) properties |= Parent->getRecursiveProperties();
   for (Type Arg : GenericArgs) {
     properties |= Arg->getRecursiveProperties();
@@ -4029,6 +4032,7 @@ EnumType::EnumType(EnumDecl *TheDecl, Type Parent, const ASTContext &C,
 
 EnumType *EnumType::get(EnumDecl *D, Type Parent, const ASTContext &C) {
   RecursiveTypeProperties properties;
+  if (D->isUnsafe()) properties |= RecursiveTypeProperties::IsUnsafe;
   if (Parent) properties |= Parent->getRecursiveProperties();
   auto arena = getArena(properties);
 
@@ -4045,6 +4049,7 @@ StructType::StructType(StructDecl *TheDecl, Type Parent, const ASTContext &C,
 
 StructType *StructType::get(StructDecl *D, Type Parent, const ASTContext &C) {
   RecursiveTypeProperties properties;
+  if (D->isUnsafe()) properties |= RecursiveTypeProperties::IsUnsafe;
   if (Parent) properties |= Parent->getRecursiveProperties();
   auto arena = getArena(properties);
 
@@ -4061,6 +4066,7 @@ ClassType::ClassType(ClassDecl *TheDecl, Type Parent, const ASTContext &C,
 
 ClassType *ClassType::get(ClassDecl *D, Type Parent, const ASTContext &C) {
   RecursiveTypeProperties properties;
+  if (D->isUnsafe()) properties |= RecursiveTypeProperties::IsUnsafe;
   if (Parent) properties |= Parent->getRecursiveProperties();
   auto arena = getArena(properties);
 
@@ -4325,20 +4331,39 @@ isAnyFunctionTypeCanonical(ArrayRef<AnyFunctionType::Param> params,
 // always materializable.
 static RecursiveTypeProperties
 getGenericFunctionRecursiveProperties(ArrayRef<AnyFunctionType::Param> params,
-                                      Type result) {
-  static_assert(RecursiveTypeProperties::BitWidth == 18,
+                                      Type result, Type globalActor,
+                                      Type thrownError) {
+  static_assert(RecursiveTypeProperties::BitWidth == 19,
                 "revisit this if you add new recursive type properties");
   RecursiveTypeProperties properties;
 
   for (auto param : params) {
     if (param.getPlainType()->getRecursiveProperties().hasError())
       properties |= RecursiveTypeProperties::HasError;
+    if (param.getPlainType()->getRecursiveProperties().isUnsafe())
+      properties |= RecursiveTypeProperties::IsUnsafe;
   }
 
   if (result->getRecursiveProperties().hasDynamicSelf())
     properties |= RecursiveTypeProperties::HasDynamicSelf;
   if (result->getRecursiveProperties().hasError())
     properties |= RecursiveTypeProperties::HasError;
+  if (result->getRecursiveProperties().isUnsafe())
+    properties |= RecursiveTypeProperties::IsUnsafe;
+  
+  if (globalActor) {
+    if (globalActor->getRecursiveProperties().hasError())
+      properties |= RecursiveTypeProperties::HasError;
+    if (globalActor->getRecursiveProperties().isUnsafe())
+      properties |= RecursiveTypeProperties::IsUnsafe;
+  }
+
+  if (thrownError) {
+    if (thrownError->getRecursiveProperties().hasError())
+      properties |= RecursiveTypeProperties::HasError;
+    if (thrownError->getRecursiveProperties().isUnsafe())
+      properties |= RecursiveTypeProperties::IsUnsafe;
+  }
 
   return properties;
 }
@@ -4671,7 +4696,8 @@ GenericFunctionType *GenericFunctionType::get(GenericSignature sig,
       hasLifetimeDependenceInfo ? numLifetimeDependencies : 0);
   void *mem = ctx.Allocate(allocSize, alignof(GenericFunctionType));
 
-  auto properties = getGenericFunctionRecursiveProperties(params, result);
+  auto properties = getGenericFunctionRecursiveProperties(
+      params, result, globalActor, thrownError);
   auto funcTy = new (mem) GenericFunctionType(sig, params, result, info,
                                               isCanonical ? &ctx : nullptr,
                                               properties);
@@ -5044,7 +5070,7 @@ CanSILFunctionType SILFunctionType::get(
   void *mem = ctx.Allocate(bytes, alignof(SILFunctionType));
 
   RecursiveTypeProperties properties;
-  static_assert(RecursiveTypeProperties::BitWidth == 18,
+  static_assert(RecursiveTypeProperties::BitWidth == 19,
                 "revisit this if you add new recursive type properties");
   for (auto &param : params)
     properties |= param.getInterfaceType()->getRecursiveProperties();
@@ -5132,6 +5158,7 @@ OptionalType *OptionalType::get(Type base) {
 ProtocolType *ProtocolType::get(ProtocolDecl *D, Type Parent,
                                 const ASTContext &C) {
   RecursiveTypeProperties properties;
+  if (D->isUnsafe()) properties |= RecursiveTypeProperties::IsUnsafe;
   if (Parent) properties |= Parent->getRecursiveProperties();
   auto arena = getArena(properties);
 
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
@@ -3489,13 +3489,31 @@ std::string ArchetypeType::getFullName() const {
   return InterfaceType.getString();
 }
 
+/// Determine the recursive type properties for an archetype.
+static RecursiveTypeProperties archetypeProperties(
+    RecursiveTypeProperties properties,
+    ArrayRef<ProtocolDecl *> conformsTo,
+    Type superclass
+) {
+  for (auto proto : conformsTo) {
+    if (proto->isUnsafe()) {
+      properties |= RecursiveTypeProperties::IsUnsafe;
+      break;
+    }
+  }
+
+  if (superclass) properties |= superclass->getRecursiveProperties();
+
+  return properties;
+}
+
 PrimaryArchetypeType::PrimaryArchetypeType(const ASTContext &Ctx,
                                      GenericEnvironment *GenericEnv,
                                      Type InterfaceType,
                                      ArrayRef<ProtocolDecl *> ConformsTo,
-                                     Type Superclass, LayoutConstraint Layout)
-  : ArchetypeType(TypeKind::PrimaryArchetype, Ctx,
-                  RecursiveTypeProperties::HasPrimaryArchetype,
+                                     Type Superclass, LayoutConstraint Layout,
+                                     RecursiveTypeProperties Properties)
+  : ArchetypeType(TypeKind::PrimaryArchetype, Ctx, Properties,
                   InterfaceType, ConformsTo, Superclass, Layout, GenericEnv)
 {
   assert(!InterfaceType->isParameterPack());
@@ -3514,14 +3532,20 @@ PrimaryArchetypeType::getNew(const ASTContext &Ctx,
   // Gather the set of protocol declarations to which this archetype conforms.
   ProtocolType::canonicalizeProtocols(ConformsTo);
 
+  RecursiveTypeProperties Properties = archetypeProperties(
+    RecursiveTypeProperties::HasPrimaryArchetype,
+    ConformsTo, Superclass);
+  assert(!Properties.hasTypeVariable());
+
   auto arena = AllocationArena::Permanent;
   void *mem = Ctx.Allocate(
     PrimaryArchetypeType::totalSizeToAlloc<ProtocolDecl *, Type, LayoutConstraint>(
           ConformsTo.size(), Superclass ? 1 : 0, Layout ? 1 : 0),
       alignof(PrimaryArchetypeType), arena);
 
   return CanPrimaryArchetypeType(::new (mem) PrimaryArchetypeType(
-      Ctx, GenericEnv, InterfaceType, ConformsTo, Superclass, Layout));
+      Ctx, GenericEnv, InterfaceType, ConformsTo, Superclass, Layout,
+      Properties));
 }
 
 OpaqueTypeArchetypeType::OpaqueTypeArchetypeType(
@@ -3573,11 +3597,10 @@ UUID OpenedArchetypeType::getOpenedExistentialID() const {
 PackArchetypeType::PackArchetypeType(
     const ASTContext &Ctx, GenericEnvironment *GenericEnv, Type InterfaceType,
     ArrayRef<ProtocolDecl *> ConformsTo, Type Superclass,
-    LayoutConstraint Layout, PackShape Shape)
-    : ArchetypeType(TypeKind::PackArchetype, Ctx,
-                    RecursiveTypeProperties::HasPrimaryArchetype |
-                    RecursiveTypeProperties::HasPackArchetype,
-                    InterfaceType, ConformsTo, Superclass, Layout, GenericEnv) {
+    LayoutConstraint Layout, PackShape Shape,
+    RecursiveTypeProperties Properties
+) : ArchetypeType(TypeKind::PackArchetype, Ctx, Properties,
+                  InterfaceType, ConformsTo, Superclass, Layout, GenericEnv) {
   assert(InterfaceType->isParameterPack());
   *getTrailingObjects<PackShape>() = Shape;
 }
@@ -3594,6 +3617,12 @@ PackArchetypeType::get(const ASTContext &Ctx,
   // Gather the set of protocol declarations to which this archetype conforms.
   ProtocolType::canonicalizeProtocols(ConformsTo);
 
+  RecursiveTypeProperties properties = archetypeProperties(
+    (RecursiveTypeProperties::HasPrimaryArchetype |
+     RecursiveTypeProperties::HasPackArchetype),
+    ConformsTo, Superclass);
+  assert(!properties.hasTypeVariable());
+
   auto arena = AllocationArena::Permanent;
   void *mem =
       Ctx.Allocate(PackArchetypeType::totalSizeToAlloc<ProtocolDecl *, Type,
@@ -3604,7 +3633,7 @@ PackArchetypeType::get(const ASTContext &Ctx,
 
   return CanPackArchetypeType(::new (mem) PackArchetypeType(
       Ctx, GenericEnv, InterfaceType, ConformsTo, Superclass, Layout,
-      {ShapeType}));
+      {ShapeType}, properties));
 }
 
 CanType PackArchetypeType::getReducedShape() {
diff --git a/lib/Sema/AssociatedTypeInference.cpp b/lib/Sema/AssociatedTypeInference.cpp
@@ -34,6 +34,7 @@
 #include "DerivedConformances.h"
 #include "TypeAccessScopeChecker.h"
 #include "TypeChecker.h"
+#include "TypeCheckType.h"
 
 #include "swift/AST/ConformanceLookup.h"
 #include "swift/AST/Decl.h"
@@ -344,6 +345,22 @@ static void recordTypeWitness(NormalProtocolConformance *conformance,
     typeDecl = aliasDecl;
   }
 
+  // If we're disallowing unsafe code, check for an unsafe type witness.
+  if (ctx.LangOpts.hasFeature(Feature::DisallowUnsafe) &&
+      !assocType->isUnsafe() && type->isUnsafe()) {
+    SourceLoc loc = typeDecl->getLoc();
+    if (loc.isInvalid())
+      loc = conformance->getLoc();
+    diagnoseUnsafeType(ctx,
+                       loc,
+                       type,
+                       [&](Type specificType) {
+      ctx.Diags.diagnose(
+          loc, diag::type_witness_unsafe, specificType, assocType->getName());
+      assocType->diagnose(diag::decl_declared_here, assocType);
+    });
+  }
+
   // Record the type witness.
   conformance->setTypeWitness(assocType, type, typeDecl);
 
diff --git a/lib/Sema/TypeCheckAvailability.cpp b/lib/Sema/TypeCheckAvailability.cpp
@@ -18,6 +18,7 @@
 #include "MiscDiagnostics.h"
 #include "TypeCheckConcurrency.h"
 #include "TypeCheckObjC.h"
+#include "TypeCheckType.h"
 #include "TypeChecker.h"
 #include "swift/AST/ASTWalker.h"
 #include "swift/AST/ClangModuleLoader.h"
@@ -3882,6 +3883,27 @@ bool ExprAvailabilityWalker::diagnoseDeclRefAvailability(
   if (diagnoseDeclAvailability(D, R, call, Where, Flags))
       return true;
 
+  // If the declaration itself is "safe" but we don't disallow unsafe uses,
+  // check whether it traffics in unsafe types.
+  ASTContext &ctx = D->getASTContext();
+  if (ctx.LangOpts.hasFeature(Feature::DisallowUnsafe) && !D->isUnsafe()) {
+    auto type = D->getInterfaceType();
+    if (auto subs = declRef.getSubstitutions())
+      type = type.subst(subs);
+    if (type->isUnsafe()) {
+      if (diagnoseUnsafeType(
+              ctx, R.Start, type,
+              [&](Type specificType) {
+                ctx.Diags.diagnose(
+                    R.Start, diag::reference_to_unsafe_typed_decl,
+                    call != nullptr && !isa<ParamDecl>(D), D,
+                    specificType);
+                D->diagnose(diag::decl_declared_here, D);
+              }))
+        return true;
+    }
+  }
+
   if (R.isValid()) {
     if (diagnoseSubstitutionMapAvailability(R.Start, declRef.getSubstitutions(),
                                             Where)) {
diff --git a/lib/Sema/TypeCheckType.cpp b/lib/Sema/TypeCheckType.cpp
@@ -6421,3 +6421,35 @@ Type ExplicitCaughtTypeRequest::evaluate(
 
   llvm_unreachable("Unhandled catch node");
 }
+
+bool swift::diagnoseUnsafeType(ASTContext &ctx, SourceLoc loc, Type type,
+                               llvm::function_ref<void(Type)> diagnose) {
+  if (!ctx.LangOpts.hasFeature(Feature::DisallowUnsafe))
+    return false;
+
+  if (!type->isUnsafe())
+    return false;
+
+  // Look for a specific @unsafe nominal type.
+  Type specificType;
+  type.findIf([&specificType](Type type) {
+    if (auto typeDecl = type->getAnyNominal()) {
+      if (typeDecl->isUnsafe()) {
+        specificType = type;
+        return true;
+      }
+    }
+
+    return false;
+  });
+
+  diagnose(specificType ? specificType : type);
+
+  if (specificType) {
+    if (auto specificTypeDecl = specificType->getAnyNominal()) {
+      specificTypeDecl->diagnose(diag::unsafe_decl_here, specificTypeDecl);
+    }
+  }
+
+  return true;
+}
diff --git a/lib/Sema/TypeCheckType.h b/lib/Sema/TypeCheckType.h
diff --git a/test/Unsafe/Inputs/unsafe_swift_decls.swift b/test/Unsafe/Inputs/unsafe_swift_decls.swift
diff --git a/test/Unsafe/unsafe.swift b/test/Unsafe/unsafe.swift
