Trick Fails to Compile Sims with enum classes

[shaferandrew]

PR #1603 (commit 763b52f), causes a syntax error when compiling a sim that uses c++ enum class.

To reproduce (using SIM_cannon_analytic as a base):

1. Create "foo.hh" in "trick_sims/Cannon/models/cannon/gravity/include/" with the following contents:

   // @trick_parse{everything}
   enum class Foo {
      a,
      b,
      c
   };

2. In SIM_cannon_analytic/S_define, add line 13 as ##include "cannon/gravity/include/foo.hh"
3. Optionally, add line 20 as Foo bar{Foo::a}; (it fails to compile even without this line).
4. Run trick-CP in the SIM_cannon_analytic directory and observe this output:

   Building with the following compilation flags:
   TRICK_CFLAGS   =  -I../models
   TRICK_CXXFLAGS =  -I../models
   SWIGing    build/home/ajshafer/dev/trick/trick_sims/Cannon/SIM_cannon_analytic/S_source_py.i
   build/home/ajshafer/dev/trick/trick_sims/Cannon/models/cannon/gravity/include/foo_py.i:20: Error: Syntax error in input(1).
   make: *** [build/Makefile_swig:55: build/home/ajshafer/dev/trick/trick_sims/Cannon/SIM_cannon_analytic/S_source_py.cpp] Error 1

5. From "foo_py.i", starting at line 18:

   enum class Foo {
   #if SWIG_VERSION > 0x040000
   %pythoncode %{
      __setattr__ = _swig_setattr_nondynamic_instance_variable(object.__setattr__)
   %}
   #endif
   
      a,
      b,
      c
   };
   #define TRICK_SWIG_DEFINED_Foo

6. Removing or commenting out lines 19 through 23 (from #if... to ...#endif) and re-running make will complete successfully.

I can't find any instances of "enum class" in the Trick testing setup.

[shaferandrew]

Interestingly, this does not seem to affect an enum class that is declared within an object.

1. Create "bar.hh" using step 1. above with these contents:

   // @trick_parse{everything}
   class Bar {
      enum class Baz{
          a,
          b,
          c
      };
   
      Baz baz{Baz::a};
   };

2. Update the S_define to include it (##include "cannon/gravity/include/bar.hh")
3. Optionally, create a Bar object in the body (Bar bar{};)

Notice that this will compile. Lines 18-32 of "bar_py.i" are below:

   class Bar {
   #if SWIG_VERSION > 0x040000
   %pythoncode %{
       __setattr__ = _swig_setattr_nondynamic_instance_variable(object.__setattr__)
   %}
   #endif

       enum class Baz{
           a,
           b,
           c
       };

       Baz baz{Baz::a};
   };

This issue may only affect an enum class that is declared outside of an encapsulating class, e.g. just within a namespace.

[alexlin0]

This is the result of #1288.

convert_swig does not understand an enum class and erroneously matches it as a regular class, adding the code above and causing the error.

[sharmeye]

Seems to be addressed in recent PR