[cxx-interop] Do not import inherited methods with rvalue this

We do not synthesize the inheritance thunks correctly for such methods. Do not try to synthesize them, as that causes issues when there are two overloads of the same method, one with rvalue this and one without.

The proper solution is tracked as #69745

Unblocks rdar://114282353

Author: egorzhdan

lib/ClangImporter/ClangImporter.cpp

@@ -5481,6 +5481,13 @@ cloneBaseMemberDecl(ValueDecl *decl, DeclContext *newContext) {
         (fn->getClangDecl() &&
          isa<clang::FunctionTemplateDecl>(fn->getClangDecl())))
       return nullptr;
+    if (auto cxxMethod =
+            dyn_cast_or_null<clang::CXXMethodDecl>(fn->getClangDecl())) {
+      // FIXME: if this function has rvalue this, we won't be able to synthesize
+      // the accessor correctly (https://github.com/apple/swift/issues/69745).
+      if (cxxMethod->getRefQualifier() == clang::RefQualifierKind::RQ_RValue)
+        return nullptr;
+    }
 
     ASTContext &context = decl->getASTContext();
     auto out = FuncDecl::createImplicit(

test/Interop/Cxx/class/inheritance/Inputs/functions.h

@@ -22,6 +22,10 @@ struct Base {
       __attribute__((swift_attr("import_unsafe"))) {
     return "Base::constInBase";
   }
+  inline const char *rvalueThisInBase() const&&
+      __attribute__((swift_attr("import_unsafe"))) {
+    return "Base::rvalueThisInBase";
+  }
   // TODO: if these are unnamed we hit an (unrelated) SILGen bug. Same for
   // subscripts.
   inline const char *takesArgsInBase(int a, int b, int c) const

test/Interop/Cxx/class/inheritance/functions-typechecker.swift

@@ -17,3 +17,6 @@ Derived().sameMethodNameSameSignature()
 Derived().sameMethodDifferentSignature(1)
 // ok, this is the base class method.
 Derived().sameMethodDifferentSignature()
+
+// FIXME: we should import this (https://github.com/apple/swift/issues/69745):
+Derived().rvalueThisInBase() // expected-error {{value of type 'Derived' has no member 'rvalueThisInBase'}}