[ClangImporter] Fix marking of protocols with missing requirements.

This doesn't actually have any effect yet, but if we start importing
both Swift 3 and Swift 4 versions of protocol requirements and the
non-active one is unavailable, we might mistakenly mark the protocol
un-implementable even when the requirements that are needed are all
there. (Hopefully we would never make a protocol /less/ available in a
newer release, of course.) The test case is designed to catch that.

Author: jrose-apple

lib/ClangImporter/ImportDecl.cpp

@@ -6758,7 +6758,7 @@ ClangImporter::Implementation::importDeclImpl(const clang::NamedDecl *ClangDecl,
     Result = converter.Visit(ClangDecl);
     HadForwardDeclaration = converter.hadForwardDeclaration();
   }
-  if (!Result && version > ImportNameVersion::Swift2) {
+  if (!Result && version == CurrentVersion) {
     // If we couldn't import this Objective-C entity, determine
     // whether it was a required member of a protocol.
     bool hasMissingRequiredMember = false;

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/APINotesFrameworkTest.apinotes

@@ -79,6 +79,12 @@ SwiftVersions:
           - Name: accessorsOnlyRenamedRetypedClass
             PropertyKind:    Class
             SwiftImportAsAccessors: true
+    Protocols:
+      - Name: ProtoWithVersionedUnavailableMember
+        Methods:
+          - Selector: requirement
+            MethodKind: Instance
+            ResultType: 'ForwardClass * _Nullable'
     Functions:
       - Name: acceptDoublePointer
         SwiftName: 'acceptPointer(_:)'

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/APINotesFrameworkTest.h

@@ -14,4 +14,6 @@ __attribute__((objc_root_class))
 @end
 
 #import <APINotesFrameworkTest/Properties.h>
+#import <APINotesFrameworkTest/Protocols.h>
+
 #endif

test/APINotes/Inputs/custom-frameworks/APINotesFrameworkTest.framework/Headers/Protocols.h

@@ -0,0 +1,9 @@
+#pragma clang assume_nonnull begin
+
+@class ForwardClass; // used by API notes
+
+@protocol ProtoWithVersionedUnavailableMember
+- (nullable id)requirement;
+@end
+
+#pragma clang assume_nonnull end

test/APINotes/versioned.swift

@@ -15,15 +15,21 @@
 
 import APINotesFrameworkTest
 
+// CHECK-DIAGS-4-NOT: versioned.swift:[[@LINE-1]]:
+class ProtoWithVersionedUnavailableMemberImpl: ProtoWithVersionedUnavailableMember {
+  // CHECK-DIAGS-3: versioned.swift:[[@LINE-1]]:7: error: type 'ProtoWithVersionedUnavailableMemberImpl' cannot conform to protocol 'ProtoWithVersionedUnavailableMember' because it has requirements that cannot be satisfied
+  func requirement() -> Any? { return nil }
+}
+
 func testRenamedTopLevel() {
   var value = 0.0
 
-  // CHECK-DIAGS-4-NOT: versioned.swift:[[@LINE+1]]
+  // CHECK-DIAGS-4-NOT: versioned.swift:[[@LINE+1]]:
   accept(&value)
   // CHECK-DIAGS-3: versioned.swift:[[@LINE-1]]:3: error: 'accept' has been renamed to 'acceptPointer(_:)'
   // CHECK-DIAGS-3: note: 'accept' was introduced in Swift 4
 
-  // CHECK-DIAGS-4-NOT: versioned.swift:[[@LINE+1]]
+  // CHECK-DIAGS-4-NOT: versioned.swift:[[@LINE+1]]:
   acceptPointer(&value)
   // CHECK-DIAGS-4: versioned.swift:[[@LINE-1]]:3: error: 'acceptPointer' has been renamed to 'accept(_:)'
   // CHECK-DIAGS-4: note: 'acceptPointer' was obsoleted in Swift 4