Be explicit about C return type returning pointers to Java

Author: TheBlueMatt

java_strings.py

@@ -241,7 +241,7 @@ class CommonBase {
 	(*env)->SetByteArrayRegion(env, ret_arr, 0, slice->datalen, slice->data);
 	return ret_arr;
 }
-JNIEXPORT long JNICALL Java_org_ldk_impl_bindings_bytes_1to_1u8_1vec (JNIEnv * env, jclass _b, jbyteArray bytes) {
+JNIEXPORT int64_t impl_bindings_bytes_1to_1u8_1vec (JNIEnv * env, jclass _b, jbyteArray bytes) {
 	LDKCVec_u8Z *vec = (LDKCVec_u8Z*)MALLOC(sizeof(LDKCVec_u8Z), "LDKCVec_u8");
 	vec->datalen = (*env)->GetArrayLength(env, bytes);
 	vec->data = (uint8_t*)MALLOC(vec->datalen, "LDKCVec_u8Z Bytes");
@@ -255,7 +255,7 @@ class CommonBase {
 	slice.datalen = txdata->datalen;
 	return Java_org_ldk_impl_bindings_get_1u8_1slice_1bytes(env, _b, (long)&slice);
 }
-JNIEXPORT long JNICALL Java_org_ldk_impl_bindings_new_1txpointer_1copy_1data (JNIEnv * env, jclass _b, jbyteArray bytes) {
+JNIEXPORT int64_t JNICALL Java_org_ldk_impl_bindings_new_1txpointer_1copy_1data (JNIEnv * env, jclass _b, jbyteArray bytes) {
 	LDKTransaction *txdata = (LDKTransaction*)MALLOC(sizeof(LDKTransaction), "LDKTransaction");
 	txdata->datalen = (*env)->GetArrayLength(env, bytes);
 	txdata->data = (uint8_t*)MALLOC(txdata->datalen, "Tx Data Bytes");
@@ -278,7 +278,7 @@ class CommonBase {
 	LDKCVec_u8Z *vec = (LDKCVec_u8Z*)ptr;
 	return (long)vec->datalen;
 }
-JNIEXPORT long JNICALL Java_org_ldk_impl_bindings_new_1empty_1slice_1vec (JNIEnv * env, jclass _b) {
+JNIEXPORT int64_t JNICALL Java_org_ldk_impl_bindings_new_1empty_1slice_1vec (JNIEnv * env, jclass _b) {
 	// Check sizes of a few Vec types are all consistent as we're meant to be generic across types
 	_Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKCVec_SignatureZ), "Vec<*> needs to be mapped identically");
 	_Static_assert(sizeof(LDKCVec_u8Z) == sizeof(LDKCVec_MessageSendEventZ), "Vec<*> needs to be mapped identically");
@@ -727,7 +727,7 @@ def native_c_map_trait(self, struct_name, field_vars, field_fns):
         out_c = out_c + "\treturn ret;\n"
         out_c = out_c + "}\n"
 
-        out_c = out_c + self.c_fn_ty_pfx + "long " + self.c_fn_name_define_pfx(struct_name + "_new", True) + "jobject o"
+        out_c = out_c + self.c_fn_ty_pfx + "int64_t " + self.c_fn_name_define_pfx(struct_name + "_new", True) + "jobject o"
         for var in field_vars:
             if isinstance(var, ConvInfo):
                 out_c = out_c + ", " + var.c_ty + " " + var.arg_name