Stream device 2.8.20 builds failure in Windows x86

[FreddieAkeroyd]

Building Stream device 2.8.20 on win32-x86 fails with the error

[2021-07-28T04:49:20.198Z] StreamEpics.cc
[2021-07-28T04:49:20.198Z] c:\instrument\apps\epics32\support\streamdevice\master\src\streamepics.cc(467) : error C2440: '=' : cannot convert from 'const char *(__stdcall *)(void)' to 'const char *(__cdecl *)(void)'
[2021-07-28T04:49:20.198Z]         This conversion requires a reinterpret_cast, a C-style cast or function-style cast

building on windows-x64 works fine.

The relevant line is

StreamGetThreadNameFunction = epicsThreadGetNameSelf;

The issue is caused by epicsThreadGetNameSelf being defined as epicsShareAPI resulting in it using the stdcall rather than default cdecl calling convention on x86, on x64 Microsoft removed stdcall and it was aliased to cdecl hence all compiles OK.

There are two options to fix this:

• modify StreamGetThreadNameFunction signature to include epicsShareAPI, however any user defined alternative functions would also need to be declared epicsShareAPI too
• create and assign a streamGetThreadNameDefaultFunction() wrapper function that just calls epicsThreadGetNameSelf()

@dirk-zimoch I am happy to submit a PR, I just wanted to check which your preference was

[dirk-zimoch]

I guess I will go with alternative 2. I am really not happy with the permanent Windows dll specific problems. Maybe I should drop Windows support to make my life easier?

[dirk-zimoch]

fixed in commit dfbd308.

[FreddieAkeroyd]

Thanks for fixing - I am happy to help with resolving any windows specific issues, having stream device supported on windows is important for us. I'm assuming EPICS has epicsShareAPI set to __stdcall for compatibility with being called from programming languages other than C/C++, though a limitation of __stdcall is that it does not support variable argument functions hence some EPICS functions (like errlogPrintf) are not declared with epicsShareAPI.