Restore compatibility with Qt 5.7.0 and 5.6.1

QSysInfo::productType() returned "osx" for all versions of macOS, even
10.12. Change 3e2bde35786 was incorrect.

[ChangeLog][Important Behavior Changes] QSysInfo::productType() and
QFileSelector behavior on macOS was restored to match what Qt used to
return in version 5.7.0 and earlier. The behavior found in Qt 5.6.2,
5.7.1 and 5.8.0 is removed.

[ChangeLog][Future Compatibility Notice] The identifiers that
QSysInfo::productType() and QFileSelector will use to identify macOS
systems will change in Qt 6.0 to match the Apple naming guidelines which
will be current then.

Task-number: QTBUG-59849
Change-Id: Ib0e40a7a3ebc44329f23fffd14b2b39392210c4f
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

src/corelib/global/qglobal.cpp

@@ -2652,12 +2652,14 @@ QString QSysInfo::kernelVersion()
     to determine the distribution name and returns that. If determining the
     distribution name failed, it returns "unknown".
 
-    \b{Darwin, \macos, iOS, tvOS, and watchOS note}: this function returns
-    "macos" for \macos systems, "ios" for iOS systems, "tvos" for tvOS systems,
-    "watchos" for watchOS systems, and "darwin" in case the system could not
-    be determined.
+    \b{\macos note}: this function returns "osx" for all \macos systems,
+    regardless of Apple naming convention. The returned string will be updated
+    for Qt 6. Note that this function erroneously returned "macos" for \macos
+    10.12 in Qt versions 5.6.2, 5.7.1, and 5.8.0.
 
-    \b{OS X note}: this function returns "osx" for versions of \macos prior to 10.12.
+    \b{Darwin, iOS, tvOS, and watchOS note}: this function returns "ios" for
+    iOS systems, "tvos" for tvOS systems, "watchos" for watchOS systems, and
+    "darwin" in case the system could not be determined.
 
     \b{FreeBSD note}: this function returns "debian" for Debian/kFreeBSD and
     "unknown" otherwise.
@@ -2692,10 +2694,12 @@ QString QSysInfo::productType()
 #elif defined(Q_OS_WATCHOS)
     return QStringLiteral("watchos");
 #elif defined(Q_OS_MACOS)
-    const QAppleOperatingSystemVersion version = qt_apple_os_version();
-    if (version.major == 10 && version.minor < 12)
-        return QStringLiteral("osx");
+    // ### Qt6: remove fallback
+#  if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     return QStringLiteral("macos");
+#  else
+    return QStringLiteral("osx");
+#  endif
 #elif defined(Q_OS_DARWIN)
     return QStringLiteral("darwin");
 

src/corelib/io/qfileselector.cpp

@@ -366,6 +366,7 @@ void QFileSelectorPrivate::updateSelectors()
 QStringList QFileSelectorPrivate::platformSelectors()
 {
     // similar, but not identical to QSysInfo::osType
+    // ### Qt6: remove macOS fallbacks to "mac" and the future compatibility
     QStringList ret;
 #if defined(Q_OS_WIN)
     // can't fall back to QSysInfo because we need both "winphone" and "winrt" for the Windows Phone case
@@ -387,12 +388,11 @@ QStringList QFileSelectorPrivate::platformSelectors()
 #     endif
 #  endif
     QString productName = QSysInfo::productType();
-#     ifdef Q_OS_MACOS
-    if (productName != QLatin1String("osx"))
-        ret << QStringLiteral("osx"); // compatibility
-#     endif
     if (productName != QLatin1String("unknown"))
-        ret << productName; // "opensuse", "fedora", "macos", "ios", "android"
+        ret << productName; // "opensuse", "fedora", "osx", "ios", "android"
+#  if defined(Q_OS_MACOS)
+    ret << QStringLiteral("macos"); // future compatibility
+#  endif
 #endif
     return ret;
 }

tests/auto/corelib/io/qfileselector/qfileselector.qrc

@@ -15,6 +15,7 @@
    <file>platforms/test</file>
    <file>platforms/+unix/+android/test</file>
    <file>platforms/+unix/+darwin/+mac/+ios/test</file>
+   <file>platforms/+unix/+darwin/+mac/+osx/+macos/test</file>
    <file>platforms/+unix/+darwin/+mac/+osx/test</file>
    <file>platforms/+unix/+darwin/+mac/test</file>
    <file>platforms/+unix/+darwin/test</file>
@@ -27,6 +28,7 @@
    <file>platforms/+windows/test</file>
    <file>platforms/+android/test</file>
    <file>platforms/+ios/test</file>
+   <file>platforms/+macos/test</file>
    <file>platforms/+osx/test</file>
    <file>platforms/+darwin/test</file>
    <file>platforms/+mac/test</file>
@@ -39,7 +41,7 @@
    <file>platforms/test2</file>
    <file>platforms/+android/test2</file>
    <file>platforms/+ios/test2</file>
-   <file>platforms/+osx/test2</file>
+   <file>platforms/+macos/test2</file>
    <file>platforms/+haiku/test2</file>
    <file>platforms/+linux/test2</file>
    <file>platforms/+wince/test2</file>
@@ -50,5 +52,11 @@
    <file>platforms/test3</file>
    <file>platforms/+windows/test3</file>
    <file>platforms/+unix/test3</file>
+
+   <!-- platforms/test4 and 5: special cases for macOS -->
+   <file>platforms/test4</file>
+   <file>platforms/+osx/test4</file>
+   <file>platforms/test5</file>
+   <file>platforms/+mac/test5</file>
 </qresource>
 </RCC>

tests/auto/corelib/io/qfileselector/tst_qfileselector.cpp

@@ -126,6 +126,14 @@ void tst_QFileSelector::basicTest_data()
     QTest::newRow("platform3") << QString(":/platforms/test3") << QStringList()
                                << expectedPlatform3File;
 
+#ifdef Q_OS_MACOS
+    // special case for compatibility code
+    QTest::newRow("osx-compat") << QString(":/platforms/test4") << QStringList()
+                                << ":/platforms/+osx/test4";
+    QTest::newRow("mac-compat") << QString(":/platforms/test5") << QStringList()
+                                << ":/platforms/+mac/test5";
+#endif
+
     QString resourceTestPath(":/extras/test");
     QString custom1("custom1");
     QTest::newRow("custom1-noselector") << resourceTestPath << QStringList()