Compilation warnings with V8 shipped with latest node [10.13 LTS]

[viktorku]

We should ideally fix these deprecations:

make[3]: warning: jobserver unavailable: using -j1.  Add '+' to parent make rule.
../buffertools.cc: In member function ‘v8::Local {anonymous}::FillAction::apply(v8::Local, const v8::FunctionCallbackInfo&, uint32_t)’:
../buffertools.cc:256:44: warning: ‘int32_t v8::Value::Int32Value() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       int c = args[args_start]->Int32Value();
                                            ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2478:46: note: declared here
   V8_DEPRECATED("Use maybe version", int32_t Int32Value() const);
                                              ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:261:43: warning: ‘v8::String::Utf8Value::Utf8Value(v8::Local)’ is deprecated: Use Isolate version [-Wdeprecated-declarations]
       String::Utf8Value s(args[args_start]);
                                           ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2892:28: note: declared here
                   explicit Utf8Value(Local obj));
                            ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:266:56: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       Local other = args[args_start]->ToObject();
                                                        ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In member function ‘v8::Local {anonymous}::IndexOfAction::apply(v8::Local, const uint8_t*, size_t, const v8::FunctionCallbackInfo&, uint32_t)’:
../buffertools.cc:329:54: warning: ‘int32_t v8::Value::Int32Value() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
     int32_t start = args[args_start + 1]->Int32Value();
                                                      ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2478:46: note: declared here
   V8_DEPRECATED("Use maybe version", int32_t Int32Value() const);
                                              ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc: In function ‘void {anonymous}::Concat(const v8::FunctionCallbackInfo&)’:
../buffertools.cc:449:29: warning: ‘v8::Local v8::Value::ToString() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       size += arg->ToString()->Utf8Length();
                             ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10040:15: note: declared here
 Local Value::ToString() const {
               ^
../buffertools.cc:449:43: warning: ‘int v8::String::Utf8Length() const’ is deprecated: Use Isolate version instead [-Wdeprecated-declarations]
       size += arg->ToString()->Utf8Length();
                                           ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2587:52: note: declared here
   V8_DEPRECATED("Use Isolate version instead", int Utf8Length() const);
                                                    ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:452:50: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       size += node::Buffer::Length(arg->ToObject());
                                                  ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc:470:30: warning: ‘v8::String::Utf8Value::Utf8Value(v8::Local)’ is deprecated: Use Isolate version [-Wdeprecated-declarations]
       String::Utf8Value v(arg);
                              ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2892:28: note: declared here
                   explicit Utf8Value(Local obj));
                            ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:475:39: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       Local b = arg->ToObject();
                                       ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::UnaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::ClearAction]’:
../buffertools.cc:431:1:   required from here
../buffertools.cc:141:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::BinaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::CompareAction]’:
../buffertools.cc:432:1:   required from here
../buffertools.cc:169:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc:177:43: warning: ‘v8::String::Utf8Value::Utf8Value(v8::Local)’ is deprecated: Use Isolate version [-Wdeprecated-declarations]
       String::Utf8Value s(args[args_start]);
                                           ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2892:28: note: declared here
                   explicit Utf8Value(Local obj));
                            ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:187:55: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       Local other = args[args_start]->ToObject();
                                                       ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::BinaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::EqualsAction]’:
../buffertools.cc:433:1:   required from here
../buffertools.cc:169:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc:177:43: warning: ‘v8::String::Utf8Value::Utf8Value(v8::Local)’ is deprecated: Use Isolate version [-Wdeprecated-declarations]
       String::Utf8Value s(args[args_start]);
                                           ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2892:28: note: declared here
                   explicit Utf8Value(Local obj));
                            ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:187:55: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       Local other = args[args_start]->ToObject();
                                                       ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::UnaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::FillAction]’:
../buffertools.cc:434:1:   required from here
../buffertools.cc:141:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::UnaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::FromHexAction]’:
../buffertools.cc:435:1:   required from here
../buffertools.cc:141:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::BinaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::IndexOfAction]’:
../buffertools.cc:436:1:   required from here
../buffertools.cc:169:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc:177:43: warning: ‘v8::String::Utf8Value::Utf8Value(v8::Local)’ is deprecated: Use Isolate version [-Wdeprecated-declarations]
       String::Utf8Value s(args[args_start]);
                                           ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/v8.h:26:0,
                 from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:2892:28: note: declared here
                   explicit Utf8Value(Local obj));
                            ^
/home/viktor/.node-gyp/10.13.0/include/node/v8config.h:324:3: note: in definition of macro ‘V8_DEPRECATED’
   declarator __attribute__((deprecated(message)))
   ^
../buffertools.cc:187:55: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       Local other = args[args_start]->ToObject();
                                                       ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::UnaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::ReverseAction]’:
../buffertools.cc:437:1:   required from here
../buffertools.cc:141:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
../buffertools.cc: In instantiation of ‘v8::Local {anonymous}::UnaryAction::operator()(const v8::FunctionCallbackInfo&) [with Derived = {anonymous}::ToHexAction]’:
../buffertools.cc:438:1:   required from here
../buffertools.cc:141:33: warning: ‘v8::Local v8::Value::ToObject() const’ is deprecated: Use maybe version [-Wdeprecated-declarations]
       target = args[0]->ToObject();
                                 ^
In file included from /home/viktor/.node-gyp/10.13.0/include/node/node.h:63:0,
                 from ../buffertools.cc:17:
/home/viktor/.node-gyp/10.13.0/include/node/v8.h:10046:15: note: declared here
 Local Value::ToObject() const {
               ^
make[3]: warning: jobserver unavailable: using -j1.  Add '+' to parent make rule.

[bnoordhuis]

Thanks for the report. I'll probably move buffertools to unsupported/unmaintained status after Node.js 11 (or whenever it won't build any more) because it's been largely subsumed by the built-in Buffer class.