Runtime: Tolerate unknown metadata kinds.

We want to be able to potentially introduce new metadata kinds in future Swift compilers, so a runtime ought to be able to degrade gracefully in the face of metadata kinds it doesn't know about. Remove attempts to exhaustively switch over metadata kinds and instead treat unknown metadata kinds as opaque.
2025-12-14 20:36:38 +01:00 · 2018-05-17 15:35:06 -07:00
parent 812e94587e
commit 681a96b45c
12 changed files with 70 additions and 391 deletions
--- a/stdlib/public/runtime/Casting.cpp
+++ b/stdlib/public/runtime/Casting.cpp
@@ -352,21 +352,13 @@ bool swift::_conformsToProtocol(const OpaqueValue *value,
      return _unknownClassConformsToObjCProtocol(value, protocol);
    return false;
 #else
-    _failCorruptType(type);
+   return false;
 #endif

+  
  case MetadataKind::Existential: // FIXME
  case MetadataKind::ExistentialMetatype: // FIXME
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Metatype:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+  default:
    return false;
  }

@@ -490,20 +482,11 @@ findDynamicValueAndType(OpaqueValue *value, const Metadata *type,
  }

  // Non-polymorphic types.
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+  default:
    outValue = value;
    outType = type;
    return;
  }
-  _failCorruptType(type);
 }

 extern "C" const Metadata *
@@ -544,23 +527,9 @@ static void deallocateDynamicValue(OpaqueValue *value, const Metadata *type) {
  }

  // None of the rest of these require deallocation.
-  case MetadataKind::Class:
-  case MetadataKind::ForeignClass:
-  case MetadataKind::ObjCClassWrapper:
-  case MetadataKind::Metatype:
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+  default:
    return;
  }
-  _failCorruptType(type);
 }

 #if SWIFT_OBJC_INTEROP
@@ -575,19 +544,7 @@ swift_dynamicCastMetatypeToObjectConditional(const Metadata *metatype) {
    return (id)metatype->getObjCClassObject();
  
  // Other kinds of metadata don't cast to AnyObject.
-  case MetadataKind::Struct:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Tuple:
-  case MetadataKind::Function:
-  case MetadataKind::Existential:
-  case MetadataKind::Metatype:
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::ForeignClass:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
+  default:
    return nullptr;
  }
 }
@@ -603,19 +560,7 @@ swift_dynamicCastMetatypeToObjectUnconditional(const Metadata *metatype) {
    return (id)metatype->getObjCClassObject();
  
  // Other kinds of metadata don't cast to AnyObject.
-  case MetadataKind::Struct:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Tuple:
-  case MetadataKind::Function:
-  case MetadataKind::Existential:
-  case MetadataKind::Metatype:
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::ForeignClass:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject: {
+  default: {
    std::string sourceName = nameForMetadata(metatype);
    swift_dynamicCastFailure(metatype, sourceName.c_str(),
                             nullptr, "AnyObject",
@@ -876,12 +821,7 @@ static bool _dynamicCastToExistential(OpaqueValue *dest,
 #endif
      LLVM_FALLTHROUGH;

-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Opaque:
-    case MetadataKind::Tuple:
+    default:
      return fallbackForNonClass();
    }

@@ -1010,7 +950,7 @@ swift_dynamicCastUnknownClassImpl(const void *object,
      = static_cast<const ObjCClassWrapperMetadata *>(targetType)->Class;
    return swift_dynamicCastObjCClass(object, targetClassType);
 #else
-    _failCorruptType(targetType);
+    return nullptr;
 #endif
  }

@@ -1019,7 +959,7 @@ swift_dynamicCastUnknownClassImpl(const void *object,
    auto targetClassType = static_cast<const ForeignClassMetadata*>(targetType);
    return swift_dynamicCastForeignClass(object, targetClassType);
 #else
-    _failCorruptType(targetType);
+    return nullptr;
 #endif
  }

@@ -1027,20 +967,9 @@ swift_dynamicCastUnknownClassImpl(const void *object,
    return _dynamicCastUnknownClassToExistential(object,
                      static_cast<const ExistentialTypeMetadata *>(targetType));
  }
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Metatype:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+  default:
    return nullptr;
  }
-  _failCorruptType(targetType);
 }

 /// Perform a dynamic class of some sort of class instance to some
@@ -1060,7 +989,7 @@ swift_dynamicCastUnknownClassUnconditionalImpl(const void *object,
      = static_cast<const ObjCClassWrapperMetadata *>(targetType)->Class;
    return swift_dynamicCastObjCClassUnconditional(object, targetClassType);
 #else
-    _failCorruptType(targetType);
+    swift_dynamicCastFailure(_swift_getClass(object), targetType);
 #endif
  }

@@ -1069,7 +998,7 @@ swift_dynamicCastUnknownClassUnconditionalImpl(const void *object,
    auto targetClassType = static_cast<const ForeignClassMetadata*>(targetType);
    return swift_dynamicCastForeignClassUnconditional(object, targetClassType);
 #else
-    _failCorruptType(targetType);
+    swift_dynamicCastFailure(_swift_getClass(object), targetType);
 #endif
  }

@@ -1082,21 +1011,10 @@ swift_dynamicCastUnknownClassUnconditionalImpl(const void *object,
    
    swift_dynamicCastFailure(_swift_getClass(object), targetType);
  }
-      
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Metatype:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+
+  default:
    swift_dynamicCastFailure(_swift_getClass(object), targetType);
  }
-  _failCorruptType(targetType);
 }

 /******************************************************************************/
@@ -1146,18 +1064,7 @@ swift_dynamicCastMetatypeImpl(const Metadata *sourceType,
      return nullptr;
    }

-    case MetadataKind::Existential:
-    case MetadataKind::ExistentialMetatype:
-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Metatype:
-    case MetadataKind::Enum:
-    case MetadataKind::Optional:
-    case MetadataKind::Opaque:
-    case MetadataKind::Struct:
-    case MetadataKind::Tuple:
+    default:
      return nullptr;
    }
    break;
@@ -1177,34 +1084,12 @@ swift_dynamicCastMetatypeImpl(const Metadata *sourceType,
              (const ClassMetadata*)targetType))
        return origSourceType;
      return nullptr;
-    case MetadataKind::Existential:
-    case MetadataKind::ExistentialMetatype:
-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Metatype:
-    case MetadataKind::Enum:
-    case MetadataKind::Optional:
-    case MetadataKind::Opaque:
-    case MetadataKind::Struct:
-    case MetadataKind::Tuple:
+    default:
      return nullptr;
    }
    break;

-  case MetadataKind::Existential:
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Metatype:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+  default:
    // The cast succeeds only if the metadata pointers are statically
    // equivalent.
    if (sourceType != targetType)
@@ -1258,18 +1143,7 @@ swift_dynamicCastMetatypeUnconditionalImpl(const Metadata *sourceType,
      // If we returned, then the cast succeeded.
      return origSourceType;
    }
-    case MetadataKind::Existential:
-    case MetadataKind::ExistentialMetatype:
-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Metatype:
-    case MetadataKind::Enum:
-    case MetadataKind::Optional:
-    case MetadataKind::Opaque:
-    case MetadataKind::Struct:
-    case MetadataKind::Tuple:
+    default:
      swift_dynamicCastFailure(sourceType, targetType);
    }
    break;
@@ -1290,41 +1164,17 @@ swift_dynamicCastMetatypeUnconditionalImpl(const Metadata *sourceType,
                                            (const ClassMetadata*)targetType);
      // If we returned, then the cast succeeded.
      return origSourceType;
-    case MetadataKind::Existential:
-    case MetadataKind::ExistentialMetatype:
-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Metatype:
-    case MetadataKind::Enum:
-    case MetadataKind::Optional:
-    case MetadataKind::Opaque:
-    case MetadataKind::Struct:
-    case MetadataKind::Tuple:
+    default:
      swift_dynamicCastFailure(sourceType, targetType);
    }
    break;
-  case MetadataKind::Existential:
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Metatype:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Struct:
-  case MetadataKind::Tuple:
+  default:
    // The cast succeeds only if the metadata pointers are statically
    // equivalent.
    if (sourceType != targetType)
      swift_dynamicCastFailure(sourceType, targetType);
    return origSourceType;
  }
-
-  swift_runtime_unreachable("Unhandled MetadataKind in switch.");
 }

 /******************************************************************************/
@@ -1688,18 +1538,10 @@ static bool _dynamicCastToMetatype(OpaqueValue *dest,
    return _dynamicCastUnknownClassToMetatype(dest, object, targetType, flags);
  }

-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
  case MetadataKind::Struct: // AnyHashable, if metatypes implement Hashable
-  case MetadataKind::Tuple:
+  default:
    return _fail(src, srcType, targetType, flags);
  }
-  _failCorruptType(srcType);
 }

 /// Perform a dynamic cast of a metatype to an existential metatype type.
@@ -1863,18 +1705,10 @@ static bool _dynamicCastToExistentialMetatype(OpaqueValue *dest,
                                                         targetType, flags);
  }

-  case MetadataKind::Function:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
  case MetadataKind::Struct:  // AnyHashable, if metatypes implement Hashable
-  case MetadataKind::Tuple:
+  default:
    return _fail(src, srcType, targetType, flags);
  }
-  _failCorruptType(srcType);
 }

 /******************************************************************************/
@@ -1935,23 +1769,9 @@ static bool _dynamicCastToFunction(OpaqueValue *dest,
                         static_cast<const ExistentialTypeMetadata*>(srcType),
                         targetType, flags);
    
-  case MetadataKind::Class:
-  case MetadataKind::Struct:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::ObjCClassWrapper:
-  case MetadataKind::ForeignClass:
-  case MetadataKind::ExistentialMetatype:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Metatype:
-  case MetadataKind::Opaque:
-  case MetadataKind::Tuple:
+  default:
    return _fail(src, srcType, targetType, flags);
  }
-
-  swift_runtime_unreachable("Unhandled MetadataKind in switch.");
 }

 /******************************************************************************/
@@ -2519,14 +2339,7 @@ static bool swift_dynamicCastImpl(OpaqueValue *dest, OpaqueValue *src,
      return _fail(src, srcType, targetType, flags);
    }

-    case MetadataKind::ExistentialMetatype:
-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Metatype:
-    case MetadataKind::Opaque:
-    case MetadataKind::Tuple:
+    default:
      return _fail(src, srcType, targetType, flags);
    }
    break;
@@ -2601,26 +2414,14 @@ static bool swift_dynamicCastImpl(OpaqueValue *dest, OpaqueValue *src,
      }
      break;

-    case MetadataKind::Existential:
-    case MetadataKind::ExistentialMetatype:
-    case MetadataKind::Function:
-    case MetadataKind::HeapLocalVariable:
-    case MetadataKind::HeapGenericLocalVariable:
-    case MetadataKind::ErrorObject:
-    case MetadataKind::Metatype:
-    case MetadataKind::Opaque:
-    case MetadataKind::Tuple:
+    default:
      break;
    }

    LLVM_FALLTHROUGH;

  // The non-polymorphic types.
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
-  case MetadataKind::Opaque:
-  case MetadataKind::Tuple:
+  default:
    // If there's an exact type match, we're done.
    if (srcType == targetType)
      return _succeed(dest, src, srcType, flags);
@@ -2643,7 +2444,6 @@ static bool swift_dynamicCastImpl(OpaqueValue *dest, OpaqueValue *src,
    // Otherwise, we have a failure.
    return _fail(src, srcType, targetType, flags);
  }
-  _failCorruptType(srcType);
 }

 static inline bool swift_isClassOrObjCExistentialTypeImpl(const Metadata *T) {
@@ -3028,19 +2828,7 @@ findBridgeWitness(const Metadata *T) {
    break;
  }

-  case MetadataKind::Class:
-  case MetadataKind::Struct:
-  case MetadataKind::Enum:
-  case MetadataKind::Optional:
-  case MetadataKind::Opaque:
-  case MetadataKind::Tuple:
-  case MetadataKind::Function:
-  case MetadataKind::Existential:
-  case MetadataKind::ObjCClassWrapper:
-  case MetadataKind::ForeignClass:
-  case MetadataKind::HeapLocalVariable:
-  case MetadataKind::HeapGenericLocalVariable:
-  case MetadataKind::ErrorObject:
+  default:
    break;
  }
  return nullptr;