Having looked at the .lib and .dll files that come with Tcl 8.6 using the dumpbin utility it looks as if the Tcl library exports the symbol _Tcl_ObjSetVar2
. Your linker error refers to this function with an imp prefixed to it which is I suspect something that Swig is creating.
What would be helpful would be doing a search through all of the code generated by Swig looking to see if the function imp_Tcl_ObjSetVar2 is defined and/or referenced. To me it seems more likely to be a wrapper function that Swig needs rather than an issue linking to the Tcl lib which doesn't contain the imp export anyway.
Update
As per the comments in addition to specifying the directory that the .lib file is located in you need to add the actual library to Configuration Properties -> Linker -> Input -> Additional Dependancies within Visual Studio.