runtime: expose the layout of SwiftError to LLDB

stdlib/public/runtime/CMakeLists.txt

@@ -39,6 +39,7 @@ set(swift_runtime_sources
     CygwinPort.cpp
     Demangle.cpp
     Enum.cpp
+    ErrorObjectConstants.cpp
     ErrorObjectNative.cpp
     Errors.cpp
     Heap.cpp

stdlib/public/runtime/ErrorObject.h

@@ -78,6 +78,7 @@ struct SwiftError : SwiftErrorHeader {
   /// This member is only available for native Swift errors.
   const WitnessTable *errorConformance;
 
+#if SWIFT_OBJC_INTEROP
   /// The base type that introduces the `Hashable` conformance.
   /// This member is only available for native Swift errors.
   /// This member is lazily-initialized.
@@ -89,6 +90,7 @@ struct SwiftError : SwiftErrorHeader {
   /// This member is lazily-initialized.
   /// Instead of using it directly, call `getHashableConformance()`.
   mutable std::atomic<const hashable_support::HashableWitnessTable *> hashableConformance;
+#endif
 
   /// Get a pointer to the value contained inside the indirectly-referenced
   /// box reference.
@@ -143,13 +145,15 @@ struct SwiftError : SwiftErrorHeader {
   const WitnessTable *getErrorConformance() const { return errorConformance; }
 #endif
 
+#if SWIFT_OBJC_INTEROP
   /// Get the base type that conforms to `Hashable`.
   /// Returns NULL if the type does not conform.
   const Metadata *getHashableBaseType() const;
 
   /// Get the `Hashable` protocol witness table for the contained type.
   /// Returns NULL if the type does not conform.
   const hashable_support::HashableWitnessTable *getHashableConformance() const;
+#endif
 
   // Don't copy or move, please.
   SwiftError(const SwiftError &) = delete;
@@ -229,6 +233,14 @@ const Metadata *getNSErrorMetadata();
 
 #endif
 
+SWIFT_RUNTIME_EXPORT
+extern "C"
+const size_t _swift_lldb_offsetof_SwiftError_typeMetadata;
+
+SWIFT_RUNTIME_EXPORT
+extern "C"
+const size_t _swift_lldb_sizeof_SwiftError;
+
 } // namespace swift
 
 #endif

stdlib/public/runtime/ErrorObjectConstants.cpp

@@ -0,0 +1,24 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2016 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#include "ErrorObject.h"
+
+using namespace swift;
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Winvalid-offsetof"
+const size_t swift::_swift_lldb_offsetof_SwiftError_typeMetadata =
+    offsetof(SwiftError, type);
+#pragma clang diagnostic pop
+
+const size_t swift::_swift_lldb_sizeof_SwiftError = sizeof(SwiftError);
+

test/1_stdlib/Runtime.swift.gyb

@@ -9,6 +9,11 @@ import Swift
 import StdlibUnittest
 import SwiftShims
 
+#if os(OSX) || os(iOS) || os(watchOS) || os(tvOS)
+import Darwin
+#elseif os(Linux) || os(FreeBSD) || os(PS4) || os(Android)
+import Glibc
+#endif
 
 @_silgen_name("swift_demangle")
 public
@@ -496,6 +501,35 @@ Runtime.test("Struct layout with reference storage types") {
   print(malkovich)
 }
 
+Runtime.test("SwiftError layout constants for LLDB") {
+#if os(OSX) || os(iOS) || os(watchOS) || os(tvOS)
+  let RTLD_DEFAULT = UnsafeMutableRawPointer(bitPattern: -2)
+#elseif os(Linux)
+  let RTLD_DEFAULT = UnsafeMutableRawPointer(bitPattern: 0)
+#else
+  _UnimplementedError()
+#endif
+
+  let offsetof_SwiftError_typeMetadata =
+    dlsym(RTLD_DEFAULT, "_swift_lldb_offsetof_SwiftError_typeMetadata")!
+  let sizeof_SwiftError =
+    dlsym(RTLD_DEFAULT, "_swift_lldb_sizeof_SwiftError")!
+#if os(OSX) || os(iOS) || os(watchOS) || os(tvOS)
+#if arch(i386) || arch(arm)
+  expectEqual(20, offsetof_SwiftError_typeMetadata.load(as: UInt.self))
+  expectEqual(36, sizeof_SwiftError.load(as: UInt.self))
+#else
+  expectEqual(40, offsetof_SwiftError_typeMetadata.load(as: UInt.self))
+  expectEqual(72, sizeof_SwiftError.load(as: UInt.self))
+#endif
+#elseif os(Linux)
+  expectEqual(16, offsetof_SwiftError_typeMetadata.load(as: UInt.self))
+  expectEqual(32, sizeof_SwiftError.load(as: UInt.self))
+#else
+  _UnimplementedError()
+#endif
+}
+
 var Reflection = TestSuite("Reflection")
 
 func wrap1   (_ x: Any) -> Any { return x }