[interop][SwiftToCxx] correctly emit names for anonymous structs that use a typedef when emitting a Clang type reference in the generated header

Author: hyp

lib/PrintAsClang/ClangSyntaxPrinter.cpp

@@ -96,6 +96,14 @@ bool ClangSyntaxPrinter::printNominalTypeOutsideMemberDeclInnerStaticAssert(
 }
 
 void ClangSyntaxPrinter::printClangTypeReference(const clang::Decl *typeDecl) {
+  if (cast<clang::NamedDecl>(typeDecl)->getDeclName().isEmpty() &&
+      isa<clang::TagDecl>(typeDecl)) {
+    if (auto *tnd =
+            cast<clang::TagDecl>(typeDecl)->getTypedefNameForAnonDecl()) {
+      printClangTypeReference(tnd);
+      return;
+    }
+  }
   auto &clangCtx = typeDecl->getASTContext();
   clang::PrintingPolicy pp(clangCtx.getLangOpts());
   const auto *NS = clang::NestedNameSpecifier::getRequiredQualification(

test/Interop/CxxToSwiftToCxx/bridge-cxx-struct-back-to-cxx.swift

@@ -80,6 +80,14 @@ namespace ns {
 
 using SimpleTypedef = int;
 
+typedef struct { float column; } anonymousStruct;
+
+namespace ns {
+
+using anonStructInNS = struct { float row; };
+
+}
+
 //--- module.modulemap
 module CxxTest {
     header "header.h"
@@ -149,6 +157,12 @@ public func takeTrivial(_ x: Trivial) {
 public func takeTrivialInout(_ x: inout Trivial) {
 }
 
+@_expose(Cxx)
+public struct Strct {
+    public let transform: anonymousStruct
+    public let transform2: ns.anonStructInNS
+}
+
 // CHECK: #if __has_feature(objc_modules)
 // CHECK: #if __has_feature(objc_modules)
 // CHECK-NEXT: #if __has_warning("-Watimport-in-framework-header")
@@ -284,3 +298,9 @@ public func takeTrivialInout(_ x: inout Trivial) {
 // CHECK: SWIFT_INLINE_THUNK void takeTrivialInout(Trivial& x) noexcept SWIFT_SYMBOL({{.*}}) {
 // CHECK-NEXT:   return _impl::$s8UseCxxTy16takeTrivialInoutyySo0E0VzF(swift::_impl::getOpaquePointer(x));
 // CHECK-NEXT: }
+
+// CHECK: SWIFT_INLINE_THUNK anonymousStruct Strct::getTransform() const {
+// CHECK-NEXT: alignas(alignof(anonymousStruct)) char storage[sizeof(anonymousStruct)];
+
+// CHECK: SWIFT_INLINE_THUNK ns::anonStructInNS Strct::getTransform2() const {
+// CHECK-NEXT: alignas(alignof(ns::anonStructInNS)) char storage[sizeof(ns::anonStructInNS)];