Fix effective context construction for NS_OPTIONS in linkage spec

lib/ClangImporter/SwiftLookupTable.h

@@ -188,6 +188,12 @@ class EffectiveClangContext {
   EffectiveClangContext(const clang::DeclContext *dc)
       : KindOrBiasedLength(DeclContext) {
     assert(dc != nullptr && "use null constructor instead");
+
+    // Skip over any linkage spec decl contexts
+    while (auto externCDecl = dyn_cast<clang::LinkageSpecDecl>(dc)) {
+      dc = externCDecl->getLexicalDeclContext();
+    }
+
     if (auto tagDecl = dyn_cast<clang::TagDecl>(dc)) {
       DC = tagDecl->getCanonicalDecl();
     } else if (auto oiDecl = dyn_cast<clang::ObjCInterfaceDecl>(dc)) {
@@ -198,11 +204,8 @@ class EffectiveClangContext {
       DC = omDecl->getCanonicalDecl();
     } else if (auto fDecl = dyn_cast<clang::FunctionDecl>(dc)) {
       DC = fDecl->getCanonicalDecl();
-    } else if (auto externCDecl = dyn_cast<clang::LinkageSpecDecl>(dc)) {
-      DC = externCDecl->getLexicalDeclContext();
     } else {
       assert(isa<clang::TranslationUnitDecl>(dc) ||
-             isa<clang::LinkageSpecDecl>(dc) ||
              isa<clang::NamespaceDecl>(dc) ||
              isa<clang::ObjCContainerDecl>(dc) &&
                  "No other kinds of effective Clang contexts");
@@ -526,7 +529,7 @@ class SwiftLookupTable {
 
   /// Retrieve the set of base names that are stored in the globals-as-members lookup table.
   SmallVector<SerializedSwiftName, 4> allGlobalsAsMembersBaseNames();
-  
+
   /// Lookup Objective-C members with the given base name, regardless
   /// of context.
   SmallVector<clang::NamedDecl *, 4>

test/Interop/Cxx/enum/Inputs/CenumsNSOptions.apinotes

@@ -8,3 +8,11 @@ Enumerators:
   SwiftName: SwiftOptionThreeApiNotes
 - Name: API_NOTES_NAMED_OptionFour
   SwiftName: SwiftOptionFourApiNotes
+Tags:
+- Name: UIPrinterJobTypes
+  SwiftName: UIPrinter.JobTypes
+SwiftVersions:
+- Version: 4
+  Tags:
+  - Name: UIPrinterJobTypes
+    SwiftName: UIPrinterJobTypes

test/Interop/Cxx/enum/Inputs/CenumsNSOptionsExternC.apinotes

@@ -0,0 +1,9 @@
+Name: CenumsNSOptionsExternC
+Tags:
+- Name: UIPrinterJobTypes
+  SwiftName: UIPrinter.JobTypes
+SwiftVersions:
+- Version: 4
+  Tags:
+  - Name: UIPrinterJobTypes
+    SwiftName: UIPrinterJobTypes

test/Interop/Cxx/enum/Inputs/c-enums-NS_OPTIONS.h

@@ -18,8 +18,10 @@ extern "C" {
 #define CF_OPTIONS(_type, _name) _type __attribute__((availability(swift, unavailable))) _name; enum __CF_OPTIONS_ATTRIBUTES : _name
 #define NS_OPTIONS(_type, _name) CF_OPTIONS(_type, _name)
 #define NS_REFINED_FOR_SWIFT __attribute__((swift_private))
+#define UIKIT_EXTERN extern "C" __attribute__((visibility("default")))
 
 typedef unsigned long NSUInteger;
+typedef long NSInteger;
 
 typedef NS_OPTIONS(NSUInteger, NSBinarySearchingOptions) {
 	NSBinarySearchingFirstEqual = (1UL << 8),
@@ -39,6 +41,23 @@ typedef NS_OPTIONS(NSUInteger, NSAttributedStringFormattingOptions) {
 - (instancetype)initWithOptions:(NSAttributedStringFormattingOptions)options
     NS_REFINED_FOR_SWIFT;
 @end
+
+UIKIT_EXTERN
+@interface UIPrinter
+
+typedef NS_OPTIONS(NSInteger, UIPrinterJobTypes) {
+  UIPrinterJobTypeUnknown = 0,
+  UIPrinterJobTypeDocument = 1 << 0,
+  UIPrinterJobTypeEnvelope = 1 << 1,
+  UIPrinterJobTypeLabel = 1 << 2,
+  UIPrinterJobTypePhoto = 1 << 3,
+  UIPrinterJobTypeReceipt = 1 << 4,
+  UIPrinterJobTypeRoll = 1 << 5,
+  UIPrinterJobTypeLargeFormat = 1 << 6,
+  UIPrinterJobTypePostcard = 1 << 7
+};
+
+@end
 }
 
 typedef NS_OPTIONS(NSUInteger, Foo) {

test/Interop/Cxx/enum/Inputs/c-enums-NS_OPTIONS_without_extern_C.h

@@ -0,0 +1,32 @@
+#if __has_attribute(enum_extensibility)
+#define __CF_ENUM_ATTRIBUTES __attribute__((enum_extensibility(open)))
+#define __CF_CLOSED_ENUM_ATTRIBUTES __attribute__((enum_extensibility(closed)))
+#define __CF_OPTIONS_ATTRIBUTES __attribute__((flag_enum,enum_extensibility(open)))
+#else
+#define __CF_ENUM_ATTRIBUTES
+#define __CF_CLOSED_ENUM_ATTRIBUTES
+#define __CF_OPTIONS_ATTRIBUTES
+#endif
+
+#define CF_OPTIONS(_type, _name) _type __attribute__((availability(swift, unavailable))) _name; enum __CF_OPTIONS_ATTRIBUTES : _name
+#define NS_OPTIONS(_type, _name) CF_OPTIONS(_type, _name)
+#define UIKIT_EXTERN extern "C" __attribute__((visibility("default")))
+
+typedef long NSInteger;
+
+UIKIT_EXTERN
+@interface UIPrinter
+
+typedef NS_OPTIONS(NSInteger, UIPrinterJobTypes) {
+  UIPrinterJobTypeUnknown = 0,
+  UIPrinterJobTypeDocument = 1 << 0,
+  UIPrinterJobTypeEnvelope = 1 << 1,
+  UIPrinterJobTypeLabel = 1 << 2,
+  UIPrinterJobTypePhoto = 1 << 3,
+  UIPrinterJobTypeReceipt = 1 << 4,
+  UIPrinterJobTypeRoll = 1 << 5,
+  UIPrinterJobTypeLargeFormat = 1 << 6,
+  UIPrinterJobTypePostcard = 1 << 7
+};
+
+@end

test/Interop/Cxx/enum/Inputs/module.modulemap

@@ -27,3 +27,8 @@ module TypedUntypedEnums {
   header "typed-untyped-enums.h"
   requires cplusplus
 }
+
+module CenumsNSOptionsExternC [extern_c] {
+  header "c-enums-NS_OPTIONS_without_extern_C.h"
+  requires cplusplus
+}

test/Interop/Cxx/enum/c-enums-NS_OPTIONS-transparent-linkage-spec-decl-modulemap-based-extern-c.swift

@@ -0,0 +1,10 @@
+// RUN: %empty-directory(%t/cache)
+// RUN: %target-swift-frontend %s -swift-version 5 -I %S/Inputs -typecheck -module-cache-path %t/cache -enable-experimental-cxx-interop 2>&1 | %FileCheck --allow-empty %s
+
+// REQUIRES: objc_interop
+
+import CenumsNSOptionsExternC
+
+// CHECK-NOT: warning: imported declaration '' could not be mapped to 'UIPrinter.JobTypes'
+// CHECK-NOT: note: please report this issue to the owners of 'CenumsNSOptions'
+

test/Interop/Cxx/enum/c-enums-NS_OPTIONS-transparent-linkage-spec-decl.swift

@@ -0,0 +1,10 @@
+// RUN: %empty-directory(%t/cache)
+// RUN: %target-swift-frontend %s -swift-version 5 -I %S/Inputs -typecheck -module-cache-path %t/cache -enable-experimental-cxx-interop 2>&1 | %FileCheck --allow-empty %s
+
+// REQUIRES: objc_interop
+
+import CenumsNSOptions
+
+// CHECK-NOT: warning: imported declaration '' could not be mapped to 'UIPrinter.JobTypes'
+// CHECK-NOT: note: please report this issue to the owners of 'CenumsNSOptions'
+