@GFLAGS_IS_A_DLL@ expands to empty string in gflags_declare.h about gflags HOT 6 CLOSED

Thanks for reporting. This mistake fall through the cracks as the header file 
is configured prior to settings GFLAGS_IS_A_DLL in the CMakeLists.txt. Also, if 
both libraries are being build, we will need to make a default choice for this 
on Windows. The exported CMake targets can have a property that specified which 
GFLAGS_DLL_DECL to use in this case.

To fix this issue, I modified the build configuration to always set 
GFLAGS_IS_A_DLL to 1 if BUILD_SHARED_LIBS is ON. You can of course always 
define GFLAGS_DLL_DECL yourself before including the header file, but as Unix 
user you should of course not have to.

This issue was closed by revision 09f7800768f8.

This issue was closed by revision 6040eac5b357.

Opened issue 78 for addressing the import definition of GFLAGS_DLL_DECL to help 
users/CMake set it properly if both shared and static libraries were 
build/installed.

This issue was closed by revision 38c4402f58ad.

Issue 81 has been merged into this issue.