How to resolve the issue "unresolved extenal symbol _DllMainCRTStartup#12"? - c++

Question

I want to build a DLL file from my source code but I had an error. During the linking, the command line couldn't resolve so many objects and abandoned the linking.
I decided to split the objects into two libraries and then to create the DLL from the two libraries.
I run my makefile but the linking is breaking up with a new error: unresolved external symbol _DllMainCRTStartup#12
I use the following settings:
Compiler options: /Od /MT /EHsc /MP /Zi /Zl /Zp8 /c /DSOMEDEFINE
Linker options: /MAPINFO:EXPORTS /SUBSYSTEM:WINDOWS /MACHINE:X86 /MANIFEST /INCREMENTAL:NO /NOLOGO /DLL /DEBUG /OUT:"$(__NAME).dll" /LIBPATH:$(__MS_LIB_PATH) \
/LIBPATH:"$(SW_HOME)\lib" /LIBPATH:"$(SW_HOME)\common\lib" /PDB:"$(__NAME).pdb" /MAP:"$(__NAME).map"
My build process runs in three steps:
first step: compile all objects
second step: use lib.exe to create two files with extension *.LIB
third step: use link.exe to create DLL file from LIB files.
but I have a linking error like in my title.
So, I suppose that the problem happens because some paths to visual studio folder during linking are not correct or during the splitting of objects in two libraries, something is going wrong and some information is gone.
Or I use not the correct options for the compiler and the linker.
Could someone help me to resolve it?

Answer 1

This is not a direct answer to your question, but an explanation in simple English of what might be the problem.
If you call a function, you first have to provide a declaration for it. The compiler will check your call against the declaration. If the function is a library function the compiler will look for it in one of the library’s interface files (GetTickCount declaration is in WinBase.h, for instance). If you do not include the file where declaration is located, the compiler will issue an error (GetTickCount not found).
If the function you are calling is a library function, you will have to provide the library where the function is implemented (GetTickCount is located in kernel32.lib). If the linker does not find the function in the provided libraries, it will issue an error (unresolved external symbol GetTickCount).
You actually do not specify any libraries in your options, just some additional library paths (/LIBPATH). Therefore the linker does not find the implementation of the functions you are calling: “During the linking, the command line couldn't resolve so many objects and abandoned the linking.” This is how automatically generated options look like (notice the differences):
/OUT:"m:\temp\Win32Project1\Release\Win32Project1.dll"
/MANIFEST
/LTCG:incremental
/NXCOMPAT
/PDB:"m:\temp\Win32Project1\Release\Win32Project1.pdb"
/DYNAMICBASE "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib"
/IMPLIB:"m:\temp\Win32Project1\Release\Win32Project1.lib"
/DEBUG
/DLL
/MACHINE:X86
/OPT:REF
/SAFESEH
/INCREMENTAL:NO
/PGD:"m:\temp\Win32Project1\Release\Win32Project1.pgd"
/SUBSYSTEM:WINDOWS
/MANIFESTUAC:"level='asInvoker' uiAccess='false'"
/ManifestFile:"Release\Win32Project1.dll.intermediate.manifest"
/OPT:ICF
/ERRORREPORT:PROMPT
/NOLOGO
/TLBID:1
Regarding the CRT, again let VC do the work for you. Let VC chose the Runtime Library:
/Yu"stdafx.h"
/GS /GL /analyze- /W3 /Gy /Zc:wchar_t /Zi /Gm- /O2
/Fd"Release\vc140.pdb"
/Zc:inline
/fp:precise
/D "WIN32" /D "NDEBUG" /D "_WINDOWS" /D "_USRDLL" /D "WIN32PROJECT1_EXPORTS" /D "_WINDLL" /D "_UNICODE" /D "UNICODE"
/errorReport:prompt
/WX-
/Zc:forScope
/Gd /Oy- /Oi /MD
/Fa"Release\"
/EHsc
/nologo
/Fo"Release\"
/Fp"Release\Win32Project1.pch"
If you insist in doing things manually, here are some interesting readings:
CRT Library Features
/MD, /MT, /LD (Use Run-Time Library)
/ENTRY (Entry-Point Symbol)