ClangImporter: Fix diagnostics for NS* prefix stripping from generic types

lib/ClangImporter/ImportDecl.cpp

@@ -1295,10 +1295,19 @@ namespace {
       auto typeDecl = dyn_cast_or_null<TypeDecl>(importedDecl);
       if (!typeDecl) return nullptr;
 
-      // FIXME: We cannot currently handle generic types.
+      // Handle generic types.
+      GenericParamList *genericParams = nullptr;
+      GenericSignature *genericSig = nullptr;
+      auto underlyingType = typeDecl->getDeclaredInterfaceType();
+
       if (auto generic = dyn_cast<GenericTypeDecl>(typeDecl)) {
-        if (generic->getGenericSignature() && !isa<ProtocolDecl>(typeDecl))
-          return nullptr;
+        if (generic->getGenericSignature() && !isa<ProtocolDecl>(typeDecl)) {
+          genericParams = generic->getGenericParams();
+          genericSig = generic->getGenericSignature();
+
+          underlyingType = ArchetypeBuilder::mapTypeIntoContext(
+              generic, underlyingType);
+        }
       }
 
       // Import the declaration context where this name will go. Note that
@@ -1310,15 +1319,15 @@ namespace {
       if (!dc) return nullptr;
 
       // Create the type alias.
-      auto underlyingType = typeDecl->getDeclaredInterfaceType();
       auto alias = Impl.createDeclWithClangNode<TypeAliasDecl>(
                      decl,
                      Impl.importSourceLoc(decl->getLocStart()),
                      swift2Name.Imported.getBaseName(),
                      Impl.importSourceLoc(decl->getLocation()),
                      TypeLoc::withoutLoc(underlyingType),
-                     /*genericparams*/nullptr, dc);
+                     genericParams, dc);
       alias->computeType();
+      alias->setGenericSignature(genericSig);
 
       // Record that this is the Swift 2 version of this declaration.
       Impl.ImportedDecls[{decl->getCanonicalDecl(), true}] = alias;

lib/Sema/ConstraintSystem.cpp

@@ -629,7 +629,11 @@ namespace {
           arguments.push_back(TypeLoc::withoutLoc(
                               replacements[gp->getCanonicalType()]));
         }
-
+
+        // FIXME: For some reason we can end up with unbound->getDecl()
+        // pointing at a generic TypeAliasDecl here. If we find a way to
+        // handle generic TypeAliases elsewhere, this can just become a
+        // call to BoundGenericType::get().
         return cs.TC.applyUnboundGenericArguments(unbound, SourceLoc(), cs.DC,
                                                   arguments,
                                                   /*isGenericSignature*/false,

lib/Sema/TypeCheckType.cpp

@@ -503,7 +503,15 @@ Type TypeChecker::applyUnboundGenericArguments(
       subs.push_back(Substitution(t.getType(), {}));
 
     auto subst = TAD->getGenericParams()->getSubstitutionMap(subs);
-    return TAD->getUnderlyingType().subst(TAD->getParentModule(), subst, None);
+
+    // FIXME: return a SubstitutedType to preserve the fact that
+    // we resolved a generic TypeAlias, for availability diagnostics.
+    // A better fix might be to introduce a BoundGenericAliasType
+    // which desugars as appropriate.
+    return SubstitutedType::get(
+        TAD->getDeclaredType(),
+        TAD->getUnderlyingType().subst(TAD->getParentModule(), subst, None),
+        Context);
   }
 
   // Form the bound generic type.

test/ClangModules/swift2_warnings.swift

@@ -12,6 +12,8 @@ func testOldTypeNames() {
 
 
   _ = NSPostingStyle(rawValue: 1) // expected-error{{'NSPostingStyle' has been renamed to 'PostingStyle'}}{{7-21=PostingStyle}}
+
+  _ = NSSoapDispenser<AnyObject>() // expected-error{{'NSSoapDispenser' has been renamed to 'SoapDispenser'}}{{7-22=SoapDispenser}}
 }
 
 func testOldMethodNames(array: NSArray) {

test/Inputs/clang-importer-sdk/usr/include/Foundation.h

@@ -1015,5 +1015,9 @@ extern NSString *NSHTTPRequestKey;
 -(void)messageSomeObject:(nonnull id)object selector:(SEL)selector;
 @end
 
+@interface NSSoapDispenser<Fragrance> : NSObject
+
+@end
+
 #define NSTimeIntervalSince1970 978307200.0
 #define NS_DO_SOMETHING 17

test/attr/attr_availability.swift

@@ -42,6 +42,11 @@ extension MyCollection {
   func append(element: T) { } // expected-error {{'T' has been renamed to 'Element'}} {{24-25=Element}}
 }
 
+@available(*, unavailable, renamed: "MyCollection")
+typealias YourCollection<Element> = MyCollection<Element> // expected-note {{'YourCollection' has been explicitly marked unavailable here}}
+
+var x : YourCollection<Int> // expected-error {{'YourCollection' has been renamed to 'MyCollection'}}{{9-23=MyCollection}}
+
 var x : int // expected-error {{'int' is unavailable: oh no you don't}}
 var y : float // expected-error {{'float' has been renamed to 'Float'}}{{9-14=Float}}