SwiftRemoteMirror: Add reflection metadata version query API

rdar://problem/27251582

Author: bitjammer

include/swift/Reflection/Records.h

@@ -19,6 +19,8 @@
 
 #include "swift/Basic/RelativePointer.h"
 
+const uint16_t SWIFT_REFLECTION_METADATA_VERSION = 1;
+
 namespace swift {
 namespace reflection {
 

include/swift/SwiftRemoteMirror/SwiftRemoteMirror.h

@@ -36,6 +36,10 @@
 extern "C" {
 #endif
 
+/// Get the metadata version supported by the Remote Mirror library.
+uint16_t
+swift_reflection_getSupportedMetadataVersion();
+
 /// \returns An opaque reflection context.
 SwiftReflectionContextRef
 swift_reflection_createReflectionContext(

stdlib/public/SwiftRemoteMirror/SwiftRemoteMirror.cpp

@@ -22,6 +22,11 @@ using namespace swift::remote;
 using NativeReflectionContext
   = ReflectionContext<External<RuntimeTarget<sizeof(uintptr_t)>>>;
 
+uint16_t
+swift_reflection_getSupportedMetadataVersion() {
+  return SWIFT_REFLECTION_METADATA_VERSION;
+}
+
 SwiftReflectionContextRef
 swift_reflection_createReflectionContext(void *ReaderContext,
                                          PointerSizeFunction getPointerSize,

tools/swift-reflection-test/swift-reflection-test.c

@@ -465,5 +465,8 @@ int main(int argc, char *argv[]) {
 
   const char *BinaryFilename = argv[1];
 
+  uint16_t Version = swift_reflection_getSupportedMetadataVersion();
+  printf("Metadata version: %u\n", Version);
+
   return doDumpHeapInstance(BinaryFilename);
 }