Android JNI gen: Don't emit code for empty RegisterNatives()

base/android/jni_generator/jni_generator.py

Index: base/android/jni_generator/jni_generator.py
diff --git a/base/android/jni_generator/jni_generator.py b/base/android/jni_generator/jni_generator.py
index 0cb70bc836b379f4bf333c4219e78ef0a858f95f..de0c152c7a21961267b449737f9b278da5d373cb 100755
--- a/base/android/jni_generator/jni_generator.py
+++ b/base/android/jni_generator/jni_generator.py
@@ -740,7 +740,7 @@ $CONSTANT_FIELDS
 // Step 2: method stubs.
 $METHOD_STUBS
 
-// Step 3: RegisterNatives.
+$STEP3_COMMENT

[Torne, 2016/08/02 12:31:40]

I'd really just leave the comment there; it's an autogenerated file, it's okay
for there to be empty sections. I don't think this is worth the complexity.

[no sievers, 2016/08/02 23:12:17]

Done.

 $JNI_NATIVE_METHODS
 $REGISTER_NATIVES
 $CLOSE_NAMESPACE
@@ -754,12 +754,17 @@ $CLOSE_NAMESPACE
         'CONSTANT_FIELDS': self.GetConstantFieldsString(),
         'METHOD_STUBS': self.GetMethodStubsString(),
         'OPEN_NAMESPACE': self.GetOpenNamespaceString(),
+        'STEP3_COMMENT': '',
         'JNI_NATIVE_METHODS': self.GetJNINativeMethodsString(),
         'REGISTER_NATIVES': self.GetRegisterNativesString(),
         'CLOSE_NAMESPACE': self.GetCloseNamespaceString(),
         'HEADER_GUARD': self.header_guard,
         'INCLUDES': self.GetIncludesString(),
     }
+    assert (values['JNI_NATIVE_METHODS'] == '') ==
+        (values['REGISTER_NATIVES'] == '')
+    if values['JNI_NATIVE_METHODS'] != '':
+      values['STEP3_COMMENT'] = '// Step 3: RegisterNatives.'
     return WrapOutput(template.substitute(values))
 
   def GetClassPathDefinitionsString(self):
@@ -829,6 +834,10 @@ ${KMETHODS}
 
   def GetRegisterNativesString(self):
     """Returns the code for RegisterNatives."""
+    natives = self.GetRegisterNativesImplString()
+    if not natives:
+      return ''
+
     template = Template("""\
 ${REGISTER_NATIVES_SIGNATURE} {
 ${EARLY_EXIT}
@@ -843,19 +852,12 @@ ${NATIVES}
   if (base::android::IsManualJniRegistrationDisabled()) return true;
 """
 
-    natives = self.GetRegisterNativesImplString()
     values = {'REGISTER_NATIVES_SIGNATURE': signature,
               'EARLY_EXIT': early_exit,
               'NATIVES': natives,
              }
 
-    func_declaration = ''
-    if not natives:
-      func_declaration = Template("""\
-${REGISTER_NATIVES_SIGNATURE} __attribute__((unused));
-""").substitute(values)
-
-    return func_declaration + template.substitute(values)
+    return template.substitute(values)
 
   def GetRegisterNativesImplString(self):
     """Returns the shared implementation for RegisterNatives."""