[odb-users] MSVC19 link error: LNK2001: Unresolved external symbol

[CETONI GmbH - Uwe Kindler]

Hi,

We use orm-odb now since some years with MinGW compiler on Windows. Now 
we decided to switch from MinGW to MSVC19 compiler from Microsoft. Whe 
could successfully build the ORM odb libraries following the 
instructions from here: 
https://codesynthesis.com/products/odb/doc/install-build2.xhtml#windows-odb

Now,  when we link our shared library that uses ODB and that implements 
the databse classes, we see the following linker error:

error LNK2001: Unresolved external symbol ""struct odb::details::share 
odb::details::shared" (?shared at details@odb@@3Ushare at 12@A)"

The symbol is declared in odb/details/shared_ptr/base.hxx:

namespace odb
{
   namespace details
   {
     struct share
     {
       explicit
       share (char id);

       bool
       operator== (share) const;

     private:
       char id_;
     };

     extern LIBODB_EXPORT share shared;
     extern LIBODB_EXPORT share exclusive;
   }
}

For me it looks like although the symbols are labeled properly with 
LIBODB_EXPORT, they are not exported properly from the DLL. The same 
code works fine with MinGW, because MinGW exports all symbols. I have no 
real idea, how to solve this issue. Has someone an idea, how this can be 
solved? Is this an ODB issue or an MSVC compiler issue - or maybe I'm 
doing something wrong:

Environment:

libodb-2.5.0-b.25
MSVC version: 19.29.30154 for 64 bit
Qt Version: 6.5.2

Compiler invocation:

cl -c -nologo -Zc:wchar_t -FS -Zc:rvalueCast -Zc:inline 
-Zc:strictStrings -Zc:throwingNew -permissive- -Zc:__cplusplus 
-Zc:externConstexpr -wd4251 -wd4996 -wd4661 -wd4244 /utf-8 -Zi -MDd 
-std:c++17 -w34100 -w34189 -w44456 -w44457 -w44458 -wd4577 -wd4467 -W2 
-W2 -W2 -W2 -EHsc /Fddebug\qtlabb_itemsd.vc.pdb -DUNICODE -D_UNICODE 
-DWIN32 -D_ENABLE_EXTENDED_ALIGNED_STORAGE -DWIN64 -DX64 
-D_HAS_AUTO_PTR_ETC=1 -DBOOST_ALL_NO_LIB -DNOMINMAX -D_HAS_STD_BYTE=1 
-DDEBUG -DUSL_QT -DADVANCED_DOCKING -DQT_QML_DEBUG -DQT_WIDGETS_LIB 
-DQT_STATEMACHINE_LIB -DQT_GUI_LIB -DQT_SQL_LIB -DQT_CORE_LIB -D_WINDL

Thank you for any help.