Node-gyp: error: exception handling disabled, use -fexceptions to enable

[mojodna]

I'm trying to update zeromq.node to use gyp as part of the process of getting it running on Windows (JustinTulloss/zeromq.node#81). I'm currently blocked by gyp's -fno-exceptions default (I think), but will probably run into linking issues soon enough.

Here's binding.gyp:

{
  'targets': [
    {
      'target_name': 'binding',
      'sources': [ 'binding.cc' ],
      'cflags': ['-fexceptions'],
      'cflags_cc': ['-fexceptions']
    }
  ]
}

Here's a transcript:

seth@lotus:~/src/JustinTulloss/zeromq.node [⚡ gyp] $ node-gyp configure --target=0.7
info it worked if it ends with ok 
spawn python [ '/Users/seth/.node-gyp/0.7/tools/gyp_addon',
  '-f',
  'make',
  '--suffix',
  '.gyp',
  '-I',
  '/Users/seth/.node-gyp/0.7/tools/patch2722.gypi',
  '-Dtarget_arch=x64' ]
info done ok 
seth@lotus:~/src/JustinTulloss/zeromq.node [⚡ gyp] $ node-gyp build
info it worked if it ends with ok 
spawn make [ 'BUILDTYPE=Release', '-f', 'Makefile.gyp' ]
  CXX(target) out/Release/obj.target/binding/binding.o
binding.cc: In constructor ‘zmq::Context::Context(int)’:
binding.cc:185: error: exception handling disabled, use -fexceptions to enable
make: *** [out/Release/obj.target/binding/binding.o] Error 1
ERR! `make` failed with exit code: 2
ERR! not ok

[TooTallNate]

Hey @mojodna. So the -fno-exceptions flag comes from node's common.gypi file. The following is supposed to negate that, try adding:

...
'cflags!': [ '-fno-exceptions' ],
'cflags_cc!': [ '-fno-exceptions' ]
...

The ! at the end is supposed to make sure that that flag is not used. Let me know if that works.

The _real_ solution however would be to remove all instances of C++-style throw statements. That's what I did for node-ffi, but I'm sure that won't be possible for every module.

[TooTallNate]

Also it looks like you are on OS X, so try also negating this entry (change it to YES): https://github.com/joyent/node/blob/2e2df04b3538c83e4e3ddc81308ca1bde3d80fc6/common.gypi#L142

[TooTallNate]

@mojodna Ok so I just confirmed that this indeed enables C++ exceptions:

{
  'targets': [
    {
      'target_name': 'bindings',
      'sources': [ 'bindings.cc' ],
      'cflags!': [ '-fno-exceptions' ],
      'cflags_cc!': [ '-fno-exceptions' ],
      'conditions': [
        ['OS=="mac"', {
          'xcode_settings': {
            'GCC_ENABLE_CPP_EXCEPTIONS': 'YES'
          }
        }]
      ]
    }
  ]
}

I'm gonna close, reopen if you're still having troubles.

[mojodna]

Awesome, thanks!

[eladb]

@mojodna Thanks. This was useful.

[victusfate]

Thanks for bringing up this issue @mojodna and for the solution @TooTallNate . I'm leveraging a number of libraries (cairo, graphicsmagick, and opencv) as well as stl code where c++ throw style exceptions are the norm.

[mildsunrise]

@TooTallNate but I want exceptions...
They make my code modular and _a lot_ easier to manage.
Is there a way to use exceptions _without_ using C++ style throw statements?

[TooTallNate]

@jmendeth You mean JavaScript exceptions?

[mildsunrise]

No, I mean using exceptions in my native (i.e. C++) code.

If I can't use exceptions, I must check the return code every time, for example.
That makes the wrapper code more bug-phrone and difficult to manage.
Don't you think?

[TooTallNate]

I don't really get what you're asking for. If you want C++ exceptions, use the gyp code posted above when building your addon. Otherwise they're disabled by default since that's how it is in node itself.

[mildsunrise]

Yeah, I'm using your gyp code right now. But you said that:

The _real_ solution however would be to remove all instances of C++-style throw statements.

So, are you saying that the real solution would be to not use exceptions at all? :S

[XadillaX]

@TooTallNate This helped me! Thanks!

[mateodelnorte]

I'm having a similar problem on centos in https://github.com/electronifie/node-python/blob/master/binding.gyp. Without the reference to fno-exceptions, I get an error telling me to use it. If I do include it, I get an error saying it can't find my exception type - which comes from a known library (Python.h).

../src/py_object_wrapper.cc: In static member function ‘static v8::Local<v8::Value> PyObjectWrapper::ConvertToJavaScript(PyObject*)’:
../src/py_object_wrapper.cc:176:16: error: expected type-specifier before ‘OverflowError’
         catch (OverflowError error) {

Any ideas?

[yhc-yhc]

thanks for this Issues, it help me to. and I use this the exception can be works:
"cflags": ['-fexceptions'],
'cflags': ['-fexceptions'],

[loretoparisi]

Here it is a more comprehensive list of flags to enable exceptions on all platforms builds:

```json
{
"conditions": [
[ "OS=='linux'", {
"cflags+": [ "-std=c++11", "-fexceptions" ],
"cflags_c+": [ "-std=c++11", "-fexceptions" ],
"cflags_cc+": [ "-std=c++11", "-fexceptions" ],
}],
[ "OS=='freebsd'", {
"cflags+": [ "-std=c++11", "-fexceptions" ],
"cflags_c+": [ "-std=c++11", "-fexceptions" ],
"cflags_cc+": [ "-std=c++11", "-fexceptions" ],
}],
[ "OS=='mac'", {
"cflags+": [ "-stdlib=libc++" ],
"xcode_settings": {
"OTHER_CPLUSPLUSFLAGS" : [ "-std=c++11", "-stdlib=libc++", "-pthread" ],
"OTHER_LDFLAGS": [ "-stdlib=libc++" ],
"GCC_ENABLE_CPP_EXCEPTIONS": "YES",
"MACOSX_DEPLOYMENT_TARGET": "10.7",
"CLANG_CXX_LANGUAGE_STANDARD":"c++11",
"CLANG_CXX_LIBRARY": "libc++"
},
}],
[
"OS=='win'", {
"cflags": [
"-Wall"
],
"defines": [
"WIN"
],
"msvs_settings": {
"VCCLCompilerTool": {
"ExceptionHandling": "2",
"DisableSpecificWarnings": [
"4244"
],
},
"VCLinkerTool": {
"LinkTimeCodeGeneration": 1,
"OptimizeReferences": 2,
"EnableCOMDATFolding": 2,
"LinkIncremental": 1,
}
}
}]
]
}