Don't declare type 'id' in the global namespace in a public header

It's not necessary, and it breaks the qttools build (where we have a
global variable named 'id'), and thus will most certainly build a lot
of existing user code.

Amends e47c22480fe84c100019cd92d0296f0dd2a7f3f1.

Change-Id: I97a91c2cb23fdae65143cf14c81570cf88d529d5
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

2 files changed, 77 insertions, 0 deletions

diff --git a/tests/auto/corelib/io/qdebug/CMakeLists.txt b/tests/auto/corelib/io/qdebug/CMakeLists.txt
index 39b92b9d2f..067e3be04b 100644
--- a/tests/auto/corelib/io/qdebug/CMakeLists.txt
+++ b/tests/auto/corelib/io/qdebug/CMakeLists.txt
@@ -10,3 +10,7 @@ qt_internal_add_test(tst_qdebug
     PUBLIC_LIBRARIES
         Qt::Concurrent
 )
+
+if (APPLE)
+    target_compile_options(tst_qdebug PRIVATE -x objective-c++)
+endif()
diff --git a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
index 9b9696d7c1..a85d8328e0 100644
--- a/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
+++ b/tests/auto/corelib/io/qdebug/tst_qdebug.cpp
@@ -52,6 +52,10 @@ struct ConvertsToQVariant {
 };
 static_assert(!QTypeTraits::has_ostream_operator_v<QDebug, ConvertsToQVariant>);
 
+#if defined(Q_OS_DARWIN)
+#include <objc/runtime.h>
+#include <Foundation/Foundation.h>
+#endif
 
 class tst_QDebug: public QObject
 {
@@ -88,6 +92,12 @@ private slots:
     void threadSafety() const;
     void toString() const;
     void noQVariantEndlessRecursion() const;
+#if defined(Q_OS_DARWIN)
+    void objcInCppMode_data() const;
+    void objcInCppMode() const;
+    void objcInObjcMode_data() const;
+    void objcInObjcMode() const;
+#endif
 };
 
 void tst_QDebug::assignment() const
@@ -873,6 +883,69 @@ void tst_QDebug::noQVariantEndlessRecursion() const
     qDebug() << var;
 }
 
+#if defined(Q_OS_DARWIN)
+
+@interface MyObjcClass : NSObject
+@end
+
+@implementation MyObjcClass : NSObject
+- (NSString *)description
+{
+    return @"MyObjcClass is the best";
+}
+@end
+
+void tst_QDebug::objcInCppMode_data() const
+{
+    QTest::addColumn<objc_object *>("object");
+    QTest::addColumn<QString>("message");
+
+    QTest::newRow("nil") << static_cast<objc_object*>(nullptr) << QString::fromLatin1("(null)");
+
+    // Not an NSObject subclass
+    auto *nsproxy = reinterpret_cast<objc_object *>(class_createInstance(objc_getClass("NSProxy"), 0));
+    QTest::newRow("NSProxy") << nsproxy << QString::fromLatin1("<NSProxy: 0x%1>").arg(uintptr_t(nsproxy), 1, 16);
+
+    // Plain NSObject
+    auto *nsobject = reinterpret_cast<objc_object *>(class_createInstance(objc_getClass("NSObject"), 0));
+    QTest::newRow("NSObject") << nsobject << QString::fromLatin1("<NSObject: 0x%1>").arg(uintptr_t(nsobject), 1, 16);
+
+    auto str = QString::fromLatin1("foo");
+    QTest::newRow("NSString") << reinterpret_cast<objc_object*>(str.toNSString()) << str;
+
+    // Custom debug description
+    QTest::newRow("MyObjcClass") << reinterpret_cast<objc_object*>([[MyObjcClass alloc] init])
+                                 << QString::fromLatin1("MyObjcClass is the best");
+}
+
+void tst_QDebug::objcInCppMode() const
+{
+    QFETCH(objc_object *, object);
+    QFETCH(QString, message);
+
+    MessageHandlerSetter mhs(myMessageHandler);
+    { qDebug() << object; }
+
+    QCOMPARE(s_msg, message);
+}
+
+void tst_QDebug::objcInObjcMode_data() const
+{
+    objcInCppMode_data();
+}
+
+void tst_QDebug::objcInObjcMode() const
+{
+    QFETCH(objc_object *, object);
+    QFETCH(QString, message);
+
+    MessageHandlerSetter mhs(myMessageHandler);
+    { qDebug() << static_cast<id>(object); }
+
+    QCOMPARE(s_msg, message);
+}
+#endif
+
 // Should compile: instentiation of unrelated operator<< should not cause cause compilation
 // error in QDebug operators (QTBUG-47375)
 class TestClassA {};