1.9 broke my call to NanThrowError

[LinusU]

LinusU/fs-xattr#8

The following code works in 1.8.x but not in 1.9.

void ThrowExceptionErrno(int e) {

  Local<Object> err = v8::Exception::Error(NanNew(errorDescriptionForGet(e)))->ToObject();
  err->Set(NanNew("errno"), NanNew<Integer>(e));
  err->Set(NanNew("code"), NanNew(errorCode(e)));

  NanThrowError(err);
}

This is the error:

In file included from ../src/xattr.cc:21:
../src/error.cc:109:3: error: call to 'NanThrowError' is ambiguous
  NanThrowError(err);
  ^~~~~~~~~~~~~
../node_modules/nan/nan.h:711:3: note: candidate function
  X(Error)
  ^
../node_modules/nan/nan.h:705:21: note: expanded from macro 'X'
    NAN_INLINE void NanThrow ## NAME(v8::Handle<v8::String> errmsg) {          \
                    ^
<scratch space>:93:1: note: expanded from here
NanThrowError
^
../node_modules/nan/nan.h:719:19: note: candidate function
  NAN_INLINE void NanThrowError(v8::Handle<v8::Value> error) {
                  ^

I think that maybe this is because of #322

[LinusU]

This code doesn't work as well:

NanThrowError(NanErrnoException(errno));

[LinusU]

The workaround/fix is quite easy thought:

NanThrowError((v8::Handle<v8::Value>) err);

[bnoordhuis]

I speculate you're hitting a compiler bug. Two NanThrowError overloads exist, one for v8::Handle<v8::Value> and one for v8::Handle<v8::String>, but they cannot conflict here: v8::Object is an instance of v8::Value but not v8::String, there is no ambiguity here.

I don't have any off-the-cuff suggestions on how to fix this in nan but what happens when you rewrite the call to NanThrowError(err.As<v8::Value>())?

EDIT: Concurrent post. :-)

[LinusU]

Yeah I thought it was strange, hmm.

Just published the fix I just posted, is there any benefit in doing err.As<v8::Value>() instead?

[bnoordhuis]

.As<T>() adds a bit more type-safety than a C style (or even C++ style) cast does. Apart from that, they're identical.

[LinusU]

Cool, I guess that it's more idiomatic then 👍

[kkoopa]

The tests don't complain with our compilers.