[cxx-interop][index] emit symbolic interface files for C++ modules

include/swift/IDE/ModuleInterfacePrinting.h

@@ -19,6 +19,10 @@
 #include <string>
 #include <vector>
 
+namespace clang {
+class Module;
+}
+
 namespace swift {
 class ASTContext;
 class ASTPrinter;
@@ -68,6 +72,10 @@ void printHeaderInterface(StringRef Filename, ASTContext &Ctx,
 void printSwiftSourceInterface(SourceFile &File, ASTPrinter &Printer,
                                const PrintOptions &Options);
 
+/// Print the symbolic Swift interface for a given imported clang module.
+void printSymbolicSwiftClangModuleInterface(ModuleDecl *M, ASTPrinter &Printer,
+                                            const clang::Module *clangModule);
+
 } // namespace ide
 
 } // namespace swift