[cxx-interop] Import custom NS_OPTIONS correctly

This changes the heuristic that we use to detect `CF_OPTIONS`/`NS_OPTIONS` instantiations in C++ language mode.

Since libraries sometimes declare custom option types that break the assumptions about the names of such types, this lifts the requirements on the type name.

rdar://113524090
rdar://113279214

Author: egorzhdan

lib/ClangImporter/ImportType.cpp

@@ -2647,43 +2647,46 @@ ArgumentAttrs ClangImporter::Implementation::inferDefaultArgument(
   } else if (const clang::TypedefType *typedefType =
                  type->getAs<clang::TypedefType>()) {
     // Get the AvailabilityAttr that would be set from CF/NS_OPTIONS
-    if (importer::isUnavailableInSwift(typedefType->getDecl(), nullptr, true)) {
+    clang::TypedefNameDecl *typedefDecl = typedefType->getDecl();
+    if (importer::isUnavailableInSwift(typedefDecl, nullptr, true)) {
       // If we've taken this branch it means we have an enum type, and it is
       // likely an integer or NSInteger that is being used by NS/CF_OPTIONS to
       // behave like a C enum in the presence of C++.
-      auto enumName = typedefType->getDecl()->getName();
-      ArgumentAttrs argumentAttrs(DefaultArgumentKind::None, true, enumName);
-      auto camelCaseWords = camel_case::getWords(enumName);
-      for (auto it = camelCaseWords.rbegin(); it != camelCaseWords.rend();
-           ++it) {
-        auto word = *it;
-        auto next = std::next(it);
-        if (camel_case::sameWordIgnoreFirstCase(word, "options")) {
-          argumentAttrs.argumentKind = DefaultArgumentKind::EmptyArray;
-          return argumentAttrs;
+      auto enumName = typedefDecl->getName();
+      // Find the next decl in the same context. If this typedef is a part of an
+      // NS/CF_OPTIONS declaration, the next decl will be an enum.
+      auto declsInContext = typedefDecl->getDeclContext()->decls();
+      auto declIter = llvm::find(declsInContext, typedefDecl);
+      if (declIter != declsInContext.end())
+        declIter++;
+      if (declIter != declsInContext.end()) {
+        if (auto enumDecl = dyn_cast<clang::EnumDecl>(*declIter)) {
+          // If this is a NS/CF_OPTIONS declaration, the enum will have no name,
+          // and all enum cases will likely be prefixed with the name of the
+          // enum.
+          bool looksLikeCFOptions =
+              !enumDecl->getIdentifier() &&
+              enumDecl->hasAttr<clang::FlagEnumAttr>() &&
+              enumDecl->hasAttr<clang::EnumExtensibilityAttr>();
+          if (looksLikeCFOptions) {
+            for (auto caseDecl : enumDecl->enumerators()) {
+              if (!caseDecl->getName().starts_with(enumName)) {
+                looksLikeCFOptions = false;
+                break;
+              }
+            }
+          }
+          if (looksLikeCFOptions) {
+            ArgumentAttrs argumentAttrs(DefaultArgumentKind::None, true,
+                                        enumName);
+            for (auto word : llvm::reverse(camel_case::getWords(enumName))) {
+              if (camel_case::sameWordIgnoreFirstCase(word, "options")) {
+                argumentAttrs.argumentKind = DefaultArgumentKind::EmptyArray;
+              }
+            }
+            return argumentAttrs;
+          }
         }
-        if (camel_case::sameWordIgnoreFirstCase(word, "units"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "domain"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "action"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "event"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "events") &&
-            next != camelCaseWords.rend() &&
-            camel_case::sameWordIgnoreFirstCase(*next, "control"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "state"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "unit"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "position") &&
-            next != camelCaseWords.rend() &&
-            camel_case::sameWordIgnoreFirstCase(*next, "scroll"))
-          return argumentAttrs;
-        if (camel_case::sameWordIgnoreFirstCase(word, "edge"))
-          return argumentAttrs;
       }
     }
   }

test/Interop/Cxx/objc-correctness/Inputs/customNSOptions.h

@@ -0,0 +1,6 @@
+#include "CFOptions.h"
+
+typedef CF_OPTIONS(unsigned, MyControlFlags) {
+  MyControlFlagsNone = 0,
+  MyControlFlagsFirst
+};

test/Interop/Cxx/objc-correctness/Inputs/module.modulemap

@@ -9,6 +9,10 @@ module CxxClassWithNSStringInit {
   requires cplusplus
 }
 
+module CustomNSOptions {
+  header "customNSOptions.h"
+}
+
 module NSOptionsMangling {
   header "NSOptionsMangling.h"
 }

test/Interop/Cxx/objc-correctness/custom-nsoptions.swift

@@ -0,0 +1,7 @@
+// RUN: %target-typecheck-verify-swift -verify-ignore-unknown -I %S/Inputs -enable-objc-interop -enable-experimental-cxx-interop
+// REQUIRES: objc_interop
+
+import CustomNSOptions
+
+let flags1: MyControlFlags = []
+let flags2: MyControlFlags = [.first]