[Backtracing] Turn off MemberImportVisibility for the Runtime module.

The Runtime module is using C++ interop, which doesn't seem to play nicely
with MemberImportVisibility.

rdar://124913332

Author: al45tair

stdlib/public/RuntimeModule/CMakeLists.txt

@@ -62,7 +62,8 @@ set(RUNTIME_COMPILE_FLAGS
   "-Xfrontend;-experimental-spi-only-imports"
   "-Xcc;-I${SWIFT_SOURCE_DIR}/include"
   "-Xcc;-I${CMAKE_BINARY_DIR}/include"
-  "-Xcc;-I${SWIFT_STDLIB_SOURCE_DIR}/public/RuntimeModule/modules")
+  "-Xcc;-I${SWIFT_STDLIB_SOURCE_DIR}/public/RuntimeModule/modules"
+  "-disable-upcoming-feature MemberImportVisibility")
 
 ###TODO: Add these when we add static linking support
 #

stdlib/public/RuntimeModule/modules/Runtime/Runtime.h

@@ -23,23 +23,29 @@
 #include "swift/Runtime/CrashInfo.h"
 
 #ifdef __cplusplus
-extern "C" {
+namespace swift {
+namespace runtime {
+
+#define EXTERN_C extern "C"
+#else
+#define EXTERN_C
 #endif
 
 // Can't import swift/Runtime/Debug.h because it assumes C++
-void swift_reportWarning(uint32_t flags, const char *message);
+EXTERN_C void swift_reportWarning(uint32_t flags, const char *message);
 
 // Returns true if the given function is a thunk function
-bool _swift_backtrace_isThunkFunction(const char *rawName);
+EXTERN_C bool _swift_backtrace_isThunkFunction(const char *rawName);
 
 // Demangle the given raw name (supports Swift and C++)
-char *_swift_backtrace_demangle(const char *rawName,
-                                size_t rawNameLength,
-                                char *outputBuffer,
-                                size_t *outputBufferSize);
+EXTERN_C char *_swift_backtrace_demangle(const char *rawName,
+                                         size_t rawNameLength,
+                                         char *outputBuffer,
+                                         size_t *outputBufferSize);
 
 #ifdef __cplusplus
-}
+} // namespace runtime
+} // namespace swift
 #endif
 
 #endif // SWIFT_BACKTRACING_RUNTIME_H