#1304 Regression for generating C++ code for a vector of a set

[Olaf Flebbe]

There seems to be a regression with respect to generating c++/java code generation.

The appended Inputfile generates valid code with swig-2.0.4, however the compiler rejects the code generated by swig-2.0.9

Error message:
JAVA_wrap.cxx:574:64: error: declaration of reference variable 'result' requires an initializer
std::vector< FederateHandleSaveStatusPair >::const_reference result;
^~~~~~
JAVA_wrap.cxx:589:66: error: 'type name' declared as a pointer to a reference of type
'std::vector<FederateHandleSaveStatusPair>::const_reference' (aka 'const std::pair<FederateHandle, SaveStatus=""> &')
(std::vector< FederateHandleSaveStatusPair >::const_reference *)&jresult = new std::vector< FederateHandleSaveStatusPair ...
^
2 errors generated.

Command line (MacosX)

swig -java -c++ -I/System/Library/Frameworks/JavaVM.framework/Headers -I/System/Library/Frameworks/JavaVM.framework/Headers -o JAVA_wrap.cxx rti1516e.i
c++ -c -I/System/Library/Frameworks/JavaVM.framework/Headers JAVA_wrap.cxx

[Olaf Flebbe]

I did a git bisect: Offending Patch is

[7d038d4bd7762fb931d3a2112788cddc952792a2] Fix scoping of forward class declarations nested within a class (for C++). Also fix %template and resolution of template parameters that are typedefs

[Michael Dickens]

I see these errors when compiling GNU Radio with its SWIG Python interface; code compilation fails only under very specific circumstances. In this case, the argument is of type "std::vector<size_t>", and the pointer type that SWIG creates to hold the argument is of type "std::vector<unsigned int>" or "std::vector<unsigned long>" apparently depending on the CPU bit size (32 or 64, respectively). "size_t" is, I believe, always "unsigned long", so compiling works on a 64-bit CPU but fails on a 32-bit CPU. I think I have a work-around for the GNU Radio code, but I'd love to see SWIG fixed. Ideally, the pointer argument would of type "std::vector<size_t>*", so that it works no matter what the typedef value of size_t is.

[Andy]

I'm seeing the same problem attempting to build Java wrappers for CRFSuite, with Swig 3.0.2 on OS X. I'm keen to see the problem fixed or hear about any useful workarounds.

[Olly Betts]

The generated C++ code from the example above compiled using SWIG 4.0.2 so closing as fixed.