JNI: Allow list of namespace to be passed into Q_DECLARE_JNI_CLASS

Make the macro variadic. For N > 2 arguments, interpret the first
N-2 arguments as nested namespaces that are declared as inline
namespaces. We can then construct the signature string from those
namespaces, so

Q_DECLARE_JNI_CLASS(String, "java/lang/String")

is equivalent to

Q_DECLARE_JNI_CLASS(java, lang, String)

except that with the second overload, the C++ type will be in the
QtJniTypes::java::lang namespace. Since both the java and the lang
namespaces are made inline, QtJniTypes::String still works.

This helps with avoiding conflicts, as there might be Java classes
in different packages, but with the same name.

Pick-to: 6.8
Change-Id: I0355239e7fc3c91cb26e041f19c4e0853d3678ac
Reviewed-by: Assam Boudjelthia <[email protected]>

2 files changed, 83 insertions, 4 deletions

diff --git a/src/corelib/kernel/qjnitypes.h b/src/corelib/kernel/qjnitypes.h
index 7794710c0e0..682a91534cc 100644
--- a/src/corelib/kernel/qjnitypes.h
+++ b/src/corelib/kernel/qjnitypes.h
@@ -13,16 +13,16 @@ QT_BEGIN_NAMESPACE
 
 // QT_TECH_PREVIEW_API
 #define Q_DECLARE_JNI_TYPE_HELPER(Type)                         \
-namespace QtJniTypes {                                          \
 struct Type##Tag { explicit Type##Tag() = default; };           \
 using Type = JObject<Type##Tag>;                                \
-}                                                               \
 
 // QT_TECH_PREVIEW_API
 #define Q_DECLARE_JNI_TYPE(Type, Signature)                     \
+namespace QtJniTypes {                                          \
 Q_DECLARE_JNI_TYPE_HELPER(Type)                                 \
+}                                                               \
 template<>                                                      \
-struct QtJniTypes::Traits<QtJniTypes::Type##Tag> {              \
+struct ::QtJniTypes::Traits<QtJniTypes::Type##Tag> {            \
     static constexpr auto signature()                           \
     {                                                           \
         constexpr QtJniTypes::CTString sig(Signature);          \
@@ -34,8 +34,10 @@ struct QtJniTypes::Traits<QtJniTypes::Type##Tag> {              \
     }                                                           \
 };                                                              \
 
-#define Q_DECLARE_JNI_CLASS(Type, Signature)                    \
+#define Q_DECLARE_JNI_CLASS_2(Type, _)                          \
 Q_DECLARE_JNI_TYPE_HELPER(Type)                                 \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(Type, Signature)   \
 template<>                                                      \
 struct QtJniTypes::Traits<QtJniTypes::Type##Tag> {              \
     static constexpr auto className()                           \
@@ -50,6 +52,70 @@ struct QtJniTypes::Traits<QtJniTypes::Type##Tag> {              \
     }                                                           \
 };                                                              \
 
+#define Q_DECLARE_JNI_CLASS_3(NS0, NS1, Type)                   \
+inline namespace NS0 {                                                 \
+inline namespace NS1 {                                                 \
+Q_DECLARE_JNI_CLASS_2(Type, Q_UNUSED(0))                        \
+}                                                               \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_3(NS0, NS1, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::Type, #NS0 "/" #NS1 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS_4(NS0, NS1, NS2, Type)              \
+inline namespace NS0 {                                                 \
+Q_DECLARE_JNI_CLASS_3(NS1, NS2, Type)                           \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_4(NS0, NS1, NS2, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::NS2::Type, #NS0 "/" #NS1 "/" #NS2 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS_5(NS0, NS1, NS2, NS3, Type)         \
+inline namespace NS0 {                                                 \
+Q_DECLARE_JNI_CLASS_4(NS1, NS2, NS3, Type)                      \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_5(NS0, NS1, NS2, NS3, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::NS2::NS3::Type, #NS0 "/" #NS1 "/" #NS2 "/" #NS3 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS_6(NS0, NS1, NS2, NS3, NS4, Type)    \
+inline namespace NS0 {                                                 \
+Q_DECLARE_JNI_CLASS_5(NS1, NS2, NS3, NS4, Type)                 \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_6(NS0, NS1, NS2, NS3, NS4, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::NS2::NS3::NS4::Type, #NS0 "/" #NS1 "/" #NS2 "/" #NS3 "/" #NS4 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS_7(NS0, NS1, NS2, NS3, NS4, NS5, Type) \
+inline namespace NS0 {                                                 \
+Q_DECLARE_JNI_CLASS_6(NS1, NS2, NS3, NS4, NS5, Type)            \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_7(NS0, NS1, NS2, NS3, NS4, NS5, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::NS2::NS3::NS4::NS5::Type, #NS0 "/" #NS1 "/" #NS2 "/" #NS3 "/" #NS4 "/" #NS5 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS_8(NS0, NS1, NS2, NS3, NS4, NS5, NS6, Type) \
+inline namespace NS0 {                                                 \
+Q_DECLARE_JNI_CLASS_7(NS1, NS2, NS3, NS4, NS5, NS6, Type)       \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_8(NS0, NS1, NS2, NS3, NS4, NS5, NS6, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::NS2::NS3::NS4::NS5::NS6::Type, #NS0 "/" #NS1 "/" #NS2 "/" #NS3 "/" #NS4 "/" #NS5 "/" #NS6 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS_9(NS0, NS1, NS2, NS3, NS4, NS5, NS6, NS7, Type) \
+inline namespace NS0 {                                                 \
+Q_DECLARE_JNI_CLASS_8(NS1, NS2, NS3, NS4, NS5, NS6, NS7, Type)  \
+}                                                               \
+
+#define Q_DECLARE_JNI_CLASS_SPECIALIZATION_9(NS0, NS1, NS2, NS3, NS4, NS5, NS6, NS7, Type) \
+    Q_DECLARE_JNI_CLASS_SPECIALIZATION_2(NS0::NS1::NS2::NS3::NS4::NS5::NS6::NS7::Type, #NS0 "/" #NS1 "/" #NS2 "/" #NS3 "/" #NS4 "/" #NS5 "/" #NS6 "/" #NS7 "/" #Type)
+
+#define Q_DECLARE_JNI_CLASS(...)                                \
+namespace QtJniTypes {                                          \
+QT_OVERLOADED_MACRO(Q_DECLARE_JNI_CLASS, __VA_ARGS__)           \
+}                                                               \
+QT_OVERLOADED_MACRO(Q_DECLARE_JNI_CLASS_SPECIALIZATION, __VA_ARGS__)
+
 // Macros for native methods
 
 namespace QtJniMethods {
diff --git a/tests/auto/corelib/kernel/qjnitypes/tst_qjnitypes.cpp b/tests/auto/corelib/kernel/qjnitypes/tst_qjnitypes.cpp
index 50dca97062c..cb9c7022b1d 100644
--- a/tests/auto/corelib/kernel/qjnitypes/tst_qjnitypes.cpp
+++ b/tests/auto/corelib/kernel/qjnitypes/tst_qjnitypes.cpp
@@ -71,6 +71,19 @@ static_assert(QtJniTypes::Traits<QtJniTypes::String[]>::signature() == "[Ljava/l
 Q_DECLARE_JNI_CLASS(QtTextToSpeech, "org/qtproject/qt/android/speech/QtTextToSpeech")
 static_assert(QtJniTypes::Traits<QtJniTypes::QtTextToSpeech>::className() == "org/qtproject/qt/android/speech/QtTextToSpeech");
 
+// declaring two types Size in different packages
+Q_DECLARE_JNI_CLASS(android, util, Size)
+// inline namespaces, so this works
+static_assert(QtJniTypes::Traits<QtJniTypes::Size>::className() == "android/util/Size");
+
+Q_DECLARE_JNI_CLASS(org, qtproject, Size)
+// this would now be ambiguous
+// static_assert(QtJniTypes::Traits<QtJniTypes::Size>::className() == "android/util/Size");
+
+// but client code can be explicit
+static_assert(QtJniTypes::Traits<QtJniTypes::android::util::Size>::className() == "android/util/Size");
+static_assert(QtJniTypes::Traits<QtJniTypes::org::qtproject::Size>::className() == "org/qtproject/Size");
+
 static_assert(QtJniTypes::fieldSignature<jint>() == "I");
 static_assert(QtJniTypes::fieldSignature<jint[]>() == "[I");
 static_assert(QtJniTypes::fieldSignature<jint>() != "X");