Visual Studio 2013 build warnings #17114
Description
Recently updated to node 8.6.0, and when I build my plugin, I get these warnings from node.h.
(when building with cmake-js which does not specify warnings to ignore)
I notice when building with node-gyp that I don't get this warning; but node-gyp adds these ignores to the build. 4267;4351;4355;4800;4251 Although I'm not sure where those come from. I did find (unrelated) this in node-gyp's addon.gypi file. and that hasn't changed since 10/20/2016 so I guess this sort of warning has been an issue on-and-off for a while; although I've had no such warnings around ObjectWrap....
'msvs_disabled_warnings': [
# warning C4251: 'node::ObjectWrap::handle_' : class 'v8::Persistent<T>'
# needs to have dll-interface to be used by
# clients of class 'node::ObjectWrap'
4251
],
This is a quote of an instance of the warning.
<user>\.cmake-js\node-x64\v8.6.0\include\node\node.h(625):
warning C4251: 'node::CallbackScope::try_catch_': class 'v8::TryCatch' needs to have dll-interface to be used by clients of class 'node::CallbackScope' (compiling source file ...]
<user>\.cmake-js\node-x64\v8.6.0\include\node\v8.h(8150): note: see declaration of 'v8::TryCatch' (compiling source file ...)
Trying to capture what it actually means in order to fix it...
line 8150 of v8.h
class V8_EXPORT TryCatch {
while the class that's using trycatch
class NODE_EXTERN CallbackScope {
public:
CallbackScope(v8::Isolate* isolate,
v8::Local<v8::Object> resource,
async_context asyncContext);
~CallbackScope();
private:
InternalCallbackScope* private_;
v8::TryCatch try_catch_; // line 625
...
The warning does go away if NODE_EXTERN is removed from the class definition. ObjectWrap has no sort of link specification on it (now). And no other class has NODE_EXTERN applied to it.
In 8.4.0 there was no such thing as 'CallbackScope' so this has been a recent addition, and the extra qualifier has been hidden by node-gyp.
Edit:
I could make this a pull request which is the one line change to node.h; but I think I'd fail because I can run no tests, and can't really get 'affect subsystems'