SWIG compilation errors due to macro usage

[Sichao25]

The use of macros in PCU.h (e.g. PCU_FORMAT_ATTRIBUTE, PCU_EXPL_INST_DECL ) causes syntax errors when compiling Python wrappers, likely due to SWIG's difficulty handling complex macros. This issue is currently ignored in the PR, but a better solution should be implemented.
Potential approaches to consider:

• Use a do-while loop to wrap the macro.
• "Lie" to SWIG and treat the macro as a regular function. See discussion here.
• Refactor macros to be SWIG-compatible.

Other suggestions are welcome.

[bobpaw]

The two macros you mentioned (PCU_FORMAT_ATTRIBUTE, PCU_EXPL_INST_DECL) aren't function-like macros so I don't think the first two approaches will work (for those specific macros). Can you upload the swig error messages?

[Sichao25]

Thanks for the input. The error message is as follows:

/lore/yus9/scorec_software/core/pcu/PCU.h:114: Error: Syntax error - possibly a missing semicolon (';').
/lore/yus9/scorec_software/core/pcu/PCU.h:158: Warning 327: Extern template ignored.
/lore/yus9/scorec_software/core/pcu/PCU.h:158: Error: Syntax error in input(1).

A semicolon is required after the command statement, not the macro.

[bobpaw]

The semicolon should be removed from the macro definition of PCU_FORMAT_ATTRIBUTE and instead added on 114.

It's valid to add extra semicolons for 156-159. I figure it's better to make swig happy than remove access to operations with the other data types.

[bobpaw]

Although if swig doesn't like explicit template instantiations maybe the #ifndef SWIG is better? I don't know that the extern keyword is really required. The extern is required to avoid re-instantiating in every translation unit that includes PCU.h.

[Sichao25]

Thanks for the solutions. Would you mind sharing your environment info, such as your SWIG version? I tried adding extra semicolons before, but it didn't work for me. I wonder if this might be environment-related.

[bobpaw]

No I tried compiling and I was wrong. It's a little more complicated with both cases:

format attributes:

• https://www.swig.org/Doc4.0/Varargs.html
• https://trac.osgeo.org/grass/ticket/308

explicit template instantiation:

• https://swig.org/Doc3.0/CPlusPlus11.html#CPlusPlus11_extern_template

[bobpaw]

Should this be closed now that #495 is merged?

[cwsmith]

Yes. Thank you.