[PrintAsObjC] Use of imported generics require the full definition. (#5518)

I'm not sure why this didn't occur to me in 8282160: of course if you
see a generic type with arguments, you need to see the @interface for
that type in order to supply the arguments. Maybe I was thinking the
generated interface would automatically import anything the module
itself imports, but that hasn't ever been true.

rdar://problem/28738008

Author: jrose-apple

lib/PrintAsObjC/PrintAsObjC.cpp

@@ -1537,7 +1537,7 @@ class ReferencedTypeFinder : private TypeVisitor<ReferencedTypeFinder> {
 
   ModuleDecl &M;
   llvm::function_ref<void(ReferencedTypeFinder &, const TypeDecl *)> Callback;
-  bool IsWithinConstrainedObjCGeneric = false;
+  bool NeedsDefinition = false;
 
   ReferencedTypeFinder(ModuleDecl &mod, decltype(Callback) callback)
     : M(mod), Callback(callback) {}
@@ -1637,29 +1637,29 @@ class ReferencedTypeFinder : private TypeVisitor<ReferencedTypeFinder> {
 
   void visitBoundGenericType(BoundGenericType *boundGeneric) {
     auto *decl = boundGeneric->getDecl();
+
+    NeedsDefinition = true;
+    Callback(*this, decl);
+    NeedsDefinition = false;
+
     bool isObjCGeneric = decl->hasClangNode();
     auto *sig = decl->getGenericSignature();
 
     for_each(boundGeneric->getGenericArgs(),
              sig->getInnermostGenericParams(),
              [&](Type argTy, GenericTypeParamType *paramTy) {
       if (isObjCGeneric && isConstrained(M, sig, paramTy))
-        IsWithinConstrainedObjCGeneric = true;
+        NeedsDefinition = true;
       visit(argTy);
-      IsWithinConstrainedObjCGeneric = false;
+      NeedsDefinition = false;
     });
-
-    // Ignore the base type; that either can't be exposed to Objective-C or
-    // was an Objective-C type to begin with. Every bound generic Swift type we
-    // care about gets mapped to a particular construct in Objective-C.
-    // (For example, Optional<NSFoo> is mapped to NSFoo *.)
   }
 
 public:
   using TypeVisitor::visit;
 
-  bool isWithinConstrainedObjCGeneric() const {
-    return IsWithinConstrainedObjCGeneric;
+  bool needsDefinition() const {
+    return NeedsDefinition;
   }
 
   static void walk(ModuleDecl &mod, Type ty, decltype(Callback) callback) {
@@ -1851,8 +1851,7 @@ class ModuleWriter {
         if (TD == container)
           return;
 
-        if (finder.isWithinConstrainedObjCGeneric() &&
-            isa<NominalTypeDecl>(TD)) {
+        if (finder.needsDefinition() && isa<NominalTypeDecl>(TD)) {
           // We can delay individual members of classes; do so if necessary.
           if (isa<ClassDecl>(container)) {
             if (!tryRequire(TD)) {

test/PrintAsObjC/Inputs/custom-modules/SingleGenericClass.h

@@ -0,0 +1,6 @@
+// This file is meant to be included with modules turned off, compiled against
+// the fake clang-importer-sdk.
+#import <Foundation.h>
+
+@interface SingleImportedObjCGeneric<A> : NSObject
+@end

test/PrintAsObjC/Inputs/custom-modules/module.map

@@ -19,6 +19,11 @@ module Base {
   }
 }
 
+module SingleGenericClass {
+  header "SingleGenericClass.h"
+  export *
+}
+
 module OverrideBase [system] {
   header "override.h"
   export *

test/PrintAsObjC/classes.swift

@@ -13,13 +13,13 @@
 // FIXME: END -enable-source-import hackaround
 
 
-// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -o %t %s -disable-objc-attr-requires-foundation-module
-// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -parse-as-library %t/classes.swiftmodule -parse -emit-objc-header-path %t/classes.h -import-objc-header %S/../Inputs/empty.h -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -emit-module -I %S/Inputs/custom-modules -o %t %s -disable-objc-attr-requires-foundation-module
+// RUN: %target-swift-frontend(mock-sdk: -sdk %S/../Inputs/clang-importer-sdk -I %t) -parse-as-library %t/classes.swiftmodule -parse -I %S/Inputs/custom-modules -emit-objc-header-path %t/classes.h -import-objc-header %S/../Inputs/empty.h -disable-objc-attr-requires-foundation-module
 // RUN: %FileCheck %s < %t/classes.h
 // RUN: %FileCheck --check-prefix=NEGATIVE %s < %t/classes.h
-// RUN: %check-in-clang %t/classes.h
-// RUN: not %check-in-clang -fno-modules -Qunused-arguments %t/classes.h
-// RUN: %check-in-clang -fno-modules -Qunused-arguments %t/classes.h -include Foundation.h -include CoreFoundation.h -include objc_generics.h
+// RUN: %check-in-clang -I %S/Inputs/custom-modules/ %t/classes.h
+// RUN: not %check-in-clang -I %S/Inputs/custom-modules/ -fno-modules -Qunused-arguments %t/classes.h
+// RUN: %check-in-clang -I %S/Inputs/custom-modules/ -fno-modules -Qunused-arguments %t/classes.h -include Foundation.h -include CoreFoundation.h -include objc_generics.h -include SingleGenericClass.h
 
 // CHECK-NOT: AppKit;
 // CHECK-NOT: Properties;
@@ -28,12 +28,14 @@
 // CHECK-NEXT: @import CoreGraphics;
 // CHECK-NEXT: @import CoreFoundation;
 // CHECK-NEXT: @import objc_generics;
+// CHECK-NEXT: @import SingleGenericClass;
 // CHECK-NOT: AppKit;
 // CHECK-NOT: Swift;
 import Foundation
 import objc_generics
 import AppKit // only used in implementations
 import CoreFoundation
+import SingleGenericClass
 
 // CHECK-LABEL: @interface A1{{$}}
 // CHECK-NEXT: init
@@ -715,6 +717,9 @@ public class NonObjCClass { }
   typealias Dipper = Spoon
   // CHECK: - (FungibleContainer<FungibleObject> * _Nonnull)fungibleContainerWithAliases:(FungibleContainer<Spoon *> * _Nullable)x;
   @objc func fungibleContainerWithAliases(_ x: FungibleContainer<Dipper>?) -> FungibleContainer<FungibleObject> { fatalError("") }
+
+  // CHECK: - (void)referenceSingleGenericClass:(SingleImportedObjCGeneric<id> * _Nullable)_;
+  func referenceSingleGenericClass(_: SingleImportedObjCGeneric<AnyObject>?) {}
 }
 // CHECK: @end
 

test/PrintAsObjC/lit.local.cfg

@@ -5,5 +5,6 @@ config.substitutions.insert(0, ('%check-in-clang',
   '%%clang -fsyntax-only -x objective-c-header -fobjc-arc -fmodules '
   '-fmodules-validate-system-headers '
   '-Weverything -Werror -Wno-unused-macros -Wno-incomplete-module '
+  '-Wno-auto-import '
   '-I %%clang-include-dir '
   '-isysroot %r/Inputs/clang-importer-sdk' % config.test_source_root) )