[Clang importer] Fix bridging of the underlying types of typedefs.

lib/ClangImporter/ImportType.cpp

@@ -684,18 +684,13 @@ namespace {
         auto typedefBridgeability = getTypedefBridgeability(underlyingType);
 
         // Figure out the typedef we should actually use.
-        auto underlyingBridgeability =
-          (Bridging == Bridgeability::Full
-             ? typedefBridgeability : Bridgeability::None);
-        SwiftTypeConverter innerConverter(Impl, AllowNSUIntegerAsInt,
-                                          underlyingBridgeability);
+        SwiftTypeConverter innerConverter(Impl, AllowNSUIntegerAsInt, Bridging);
         auto underlyingResult = innerConverter.Visit(underlyingType);
 
         // If we used different bridgeability than this typedef normally
-        // would because we're in a non-bridgeable context, and therefore
-        // the underlying type is different from the mapping of the typedef,
-        // use the underlying type.
-        if (underlyingBridgeability != typedefBridgeability &&
+        // would, and therefore the underlying type is different from the
+        // mapping of the typedef, use the underlying type.
+        if (Bridging != typedefBridgeability &&
             !underlyingResult.AbstractType->isEqual(mappedType)) {
           return underlyingResult;
         }

test/ClangImporter/Inputs/custom-modules/ObjCParseExtras.h

@@ -203,3 +203,9 @@ typedef SomeCell <NSCopying> *CopyableSomeCell;
 @property (class, readonly) InstancetypeAccessor *prop;
 + (instancetype)prop;
 @end
+
+typedef NSArray<NSString *> *NSStringArray;
+
+@interface BridgedTypedefs : NSObject
+@property (readonly,nonnull) NSArray<NSStringArray> *arrayOfArrayOfStrings;
+@end

test/ClangImporter/objc_parse.swift

@@ -638,3 +638,8 @@ func testTypeAndValue() {
   let _: () -> testStruct = testStruct.init
   let _: (CInt) -> testStruct = testStruct.init
 }
+
+// rdar://problem/34913507
+func testBridgedTypedef(bt: BridgedTypedefs) {
+  let _: Int = bt.arrayOfArrayOfStrings // expected-error{{'[[String]]'}}
+}