Name callback data structs

[jschueller]

Rationale: this allows to forward-declare callback data types in case a callback needs to be declared in a public header:

struct _HighsCallbackDataOut;
struct _HighsCallbackDataIn;
typedef _HighsCallbackDataOut HighsCallbackDataOut; typedef _HighsCallbackDataIn HighsCallbackDataIn;

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.08%. Comparing base (869cbd4) to head (fe506f8).
⚠️ Report is 576 commits behind head on latest.

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #2625      +/-   ##
==========================================
+ Coverage   81.06%   81.08%   +0.01%     
==========================================
  Files         347      347              
  Lines       85219    85313      +94     
==========================================
+ Hits        69083    69176      +93     
- Misses      16136    16137       +1     

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[galabovaa]

@jschueller Would

typedef struct HighsCallbackDataOut {
...

without

typedef _HighsCallbackDataOut HighsCallbackDataOut; 

allow forward-declaring as well? Could you give us an example of the code you need to build, if possible? If you define another HighsCallbackDataOut would that not be an issue?

[jschueller]

no, that wouldnt work (error: conflicting declaration ‘typedef struct HighsCallbackDataOut HighsCallbackDataOut’)

here is what I'm trying to do in a nutshell:

Solver.hxx:

#include <iostream>

// predeclaration (public header, so we cannot use highs.h here)
struct _HighsCallbackDataOut;
struct _HighsCallbackDataIn;
typedef _HighsCallbackDataOut HighsCallbackDataOut;
typedef _HighsCallbackDataIn HighsCallbackDataIn;


class Solver
{
public:
  Solver() {};
  void run() {};

protected:
  // we need to declare this here because we want to access protected member of the Solver class
  static void Callback(const int callback_type,
                       const char* message,
                       const HighsCallbackDataOut* data_out,
                       HighsCallbackDataIn* data_in,
                       void* user_callback_data);
};

Solver.cxx:

#include "Solver.hxx"

// actual include of highs
#include <Highs.h>


void Solver::Callback(const int callback_type,
                       const char* message,
                       const HighsCallbackDataOut* data_out,
                       HighsCallbackDataIn* data_in,
                       void* user_callback_data) {}

[galabovaa]

I tried this minimal example locally, and, with the HiGHS code from latest, simply declaring the struct compiled as well:

Solver.hxx

#include <iostream>

struct HighsCallbackDataOut;
struct HighsCallbackDataIn;

class Solver
{
public:
  Solver() {};
  void run() {};

protected:
  static void Callback(const int callback_type,
                       const char* message,
                       const HighsCallbackDataOut* data_out,
                       HighsCallbackDataIn* data_in,
                       void* user_callback_data);
};

and
Solver.cxx

#include "Solver.hxx"

// actual include of highs
#include <Highs.h>


void Solver::Callback(const int callback_type,
                       const char* message,
                       const HighsCallbackDataOut* data_out,
                       HighsCallbackDataIn* data_in,
                       void* user_callback_data) {}
                       

This way you still include Highs.h only in your implementation file. Do you get a different error?

[jschueller]

yes, I still get a conflicting declaration with your solution

I prepared a repo to replicate the issue, see the github actions logs:
https://github.com/jschueller/hello-highs.git

[jschueller]

hello @galabovaa, any new thoughts on this ?

[galabovaa]

I have not had a chance to investigate properly yet. Some of us were at a conference and we have some new developments to complete. We will likely accept this, I just need to try it out myself first