Add support for naming JNI functions with the unstringify macro

The manually defined native JNI function tables allow defining a name
that may be different from the actual function name; this name is then
used from the Java-side.

This can be useful to provide also as an option with the new
"unstringifying" macros which can help for example in porting code
to these new macros.

Change-Id: Icfebfb351cb8dfb122795d20b37e2eac167a41bf
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit 58fd12a487cd2c628d713d1c42f8b53f8c4e9550)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/kernel/qjnitypes.h

@@ -349,17 +349,22 @@ constexpr auto QtJniTypes::typeSignature<QtJniTypes::Type>()    \
          + QtJniTypes::String(";");                             \
 }                                                               \
 
+#define Q_DECLARE_JNI_NATIVE_METHOD(...)                           \
+    QT_OVERLOADED_MACRO(QT_DECLARE_JNI_NATIVE_METHOD, __VA_ARGS__) \
 
-#define Q_DECLARE_JNI_NATIVE_METHOD(Method)                     \
+#define QT_DECLARE_JNI_NATIVE_METHOD_2(Method, Name)            \
 namespace QtJniMethods {                                        \
 static constexpr auto Method##_signature =                      \
     QtJniTypes::nativeMethodSignature(Method);                  \
 static const JNINativeMethod Method##_method = {                \
-    #Method, Method##_signature.data(),                         \
+    #Name, Method##_signature.data(),                           \
     reinterpret_cast<void *>(Method)                            \
 };                                                              \
 }                                                               \
 
+#define QT_DECLARE_JNI_NATIVE_METHOD_1(Method)                  \
+    QT_DECLARE_JNI_NATIVE_METHOD_2(Method, Method)              \
+
 #define Q_JNI_NATIVE_METHOD(Method) QtJniMethods::Method##_method
 
 QT_END_NAMESPACE

tests/auto/corelib/kernel/qjnienvironment/testdata/src/org/qtproject/qt/android/testdata/QtJniEnvironmentTestClass.java

@@ -6,6 +6,7 @@ package org.qtproject.qt.android.testdatapackage;
 public class QtJniEnvironmentTestClass
 {
     private static native void callbackFromJava(String message);
+    private static native void namedCallbackFromJava(String message);
     private static native void intCallbackFromJava(int value);
 
     public final int INT_FIELD = 123;
@@ -18,6 +19,11 @@ public class QtJniEnvironmentTestClass
         callbackFromJava("From Java: " + message);
     }
 
+    public static void namedAppendJavaToString(String message)
+    {
+        namedCallbackFromJava("From Java (named): " + message);
+    }
+
     public static void convertToInt(String message)
     {
         intCallbackFromJava(Integer.parseInt(message));

tests/auto/corelib/kernel/qjnienvironment/tst_qjnienvironment.cpp

@@ -101,6 +101,13 @@ static void callbackFromJava(JNIEnv *env, jobject /*thiz*/, jstring value)
 }
 Q_DECLARE_JNI_NATIVE_METHOD(callbackFromJava);
 
+static void tediouslyLongNamed_callbackFromJava(JNIEnv *env, jobject /*thiz*/, jstring value)
+{
+    Q_UNUSED(env)
+    registerNativesString = QJniObject(value).toString();
+}
+Q_DECLARE_JNI_NATIVE_METHOD(tediouslyLongNamed_callbackFromJava, namedCallbackFromJava)
+
 static void callbackFromJavaNoCtor(JNIEnv *env, jobject /*thiz*/, jstring value)
 {
     Q_UNUSED(env)
@@ -126,6 +133,20 @@ void tst_QJniEnvironment::registerNativeMethods()
         QVERIFY(registerNativesString == QStringLiteral("From Java: Qt"));
     }
 
+    // Named native function
+    {
+        QVERIFY(env.registerNativeMethods(javaTestClass, {
+            Q_JNI_NATIVE_METHOD(tediouslyLongNamed_callbackFromJava)
+        }));
+
+        QJniObject::callStaticMethod<void>(javaTestClass,
+                                           "namedAppendJavaToString",
+                                           "(Ljava/lang/String;)V",
+                                            QtString.object<jstring>());
+        QTest::qWait(200);
+        QVERIFY(registerNativesString == QStringLiteral("From Java (named): Qt"));
+    }
+
     // No default constructor in class
     {
         QVERIFY(env.registerNativeMethods(javaTestClassNoCtor, {