[BUG]Fail to build static library

[JackBoosY]

Hi Developers,
Recently, I tried to upgrade openimageio to the latest version in vcpkg(#8543), but there were some errors in the static build.

Describe the bug

timer.cpp(15): error C2491: 'OpenImageIO_v2_1::Timer::seconds_per_tick': definition of dllimport static data member not allowed
benchmark.cpp(35): error C2491: 'OpenImageIO_v2_1::clobber': definition of dllimport function not allowed
benchmark.cpp(116): error C2491: 'OpenImageIO_v2_1::operator <<': definition of dllimport function not allowed
...

After looking at the code, I found that the declaration of these functions is marked as OIIO_API, and this macro is defined as OIIO_EXPORT/OIIO_IMPORT in export.h:57-61, however its conditions OpenImageIO_EXPORTS and OpenImageIO_Util_EXPORTS are not defined in any cmake files， and I removed the declaration of seconds_per_tick under static build.

Then I defined these macros in SOURCE_PATH/CMakeLists.txt according to BUILD_SHARED_LIBS, and the following error occurred after rebuilding:

timer.h(171): error C2597: illegal reference to non-static member 'OpenImageIO_v2_1::Timer::seconds_per_tick'
timer.h(171): error C3867: 'OpenImageIO_v2_1::Timer::seconds_per_tick': non-standard syntax; use '&' to create a pointer to member

Put the initialization of seconds_per_tick into the constructor of class Timer.
Remove the static declaration from the static build in Timer::seconds. Then rebuild:

timer.h(157): error C2662: 'double OpenImageIO_v2_1::Timer::seconds(OpenImageIO_v2_1::Timer::ticks_t)': cannot convert 'this' pointer from 'const OpenImageIO_v2_1::Timer' to 'OpenImageIO_v2_1::Timer &'
timer.cpp(15): error C2761: 'double OpenImageIO_v2_1::Timer::seconds_per_tick': redeclaration of member is not allowed
timer.cpp(26): error C2597: illegal reference to non-static member 'OpenImageIO_v2_1::Timer::seconds_per_tick'

After looking at the constructor of the class TimerSetupOnce, I found that the seconds_per_tick was called here, but the instance pointer of the class Timer was not imported, which caused the Timer::seconds_per_tick not to be called here.

To Reproduce
Steps to reproduce the behavior:

1. Clone vcpkg from this repo.
2. ./bootstrap.bat
3. ./vcpkg.exe install openimageio:x64-windows-static

Expected behavior
Build successful.

Evidence
See the details above.

Platform information:

• OIIO branch/version: master - 781bc97
• OS: Windows 10 Enterprise 1903
• C++ compiler: Visual Studio 2017 ver 15.9.13
• Any non-default build flags when you build OIIO:
  See changes here.

Can anyone help me?

Thanks.

[JackBoosY]

After add -DOIIO_STATIC_DEFINE=1 to SOURCE/src/cmake/compiler.cmake line 454, this issue solved.

[lgritz]

aha, very interesting! I see the typo now...

[lgritz]

Proper fix in #2442