How to create a C++ DLL using another C++ LIB? - c++

Question

I'm trying to generate a DLL based on existing software pieces compiled in a static library (.lib) file. I'm using Visual Studio 2019, and the target is purely Windows.
The existing project (P1) have the following function :
int runLocal();
It's compiled to P1.lib.
In my new DLL project (P2), I have the following code :
#include "..\path\to\P1.h" // declaration of "int runLocal()"
extern "C" __declspec(dllexport) int __stdcall DLLMain() {
int res = runLocal();
std::cout << res << std::endl;
}
Project P2 (DLL) have following linker options :
Additional dependencies: D:\path\to\P1.lib;%(AdditionalDependencies)
However the linker "refuse" to see or use the lib file, and I get this error :
LNK2001 unresolved external symbol "int __stdcall runLocal(void)" (?runLocal##YGHXZ).
In fact, I get excatly the same error if I didn't tell the linker to use P1.lib file.
I have control over all the project sources, so I can change stuffs where it's necessary.
Note 1: The P2 project is used by a debug application (a third project compiled separately) that use LoadLibrary() to run the exported DLLMain function.
Note 2: I already succeeded in compiling an exe file against the same .lib file using the same method. So the difference seems to be in the DLL generation.
Note 3: I tried (without success) to play with many options in Visual project properties, in both compiler & linker section, at least the options that are not beyond my understanding.
So, what should I do to link correctly the .lib file and create my dll ?
Edit 1: I add the compiler & linker options:
P1 compiler options:
/permissive- /GS /TP /GL /analyze- /W3 /Gy /Zc:wchar_t
/I"C:\_tools\boost_1_68_0\" /I"C:\_tools\cryptopp_8_2_0\"
/Qspectre /guard:cf /Zi /Gm- /O2 /sdl /Fd"tmp_Win32_Release\p1.pdb" /Zc:inline
/fp:precise /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "_CRT_SECURE_NO_WARNINGS"
/D "_UNICODE" /D "UNICODE" /D "_AFXDLL"
/errorReport:prompt /WX- /Zc:forScope /Gd /Oy /Oi /MD /std:c++17 /FC
/Fa"tmp_Win32_Release\" /EHsc /nologo
/Fo"tmp_Win32_Release\" /Ot /Fp"tmp_Win32_Release\p1.pch" /diagnostics:column
P1 librarian options:
/OUT:"D:\Projets\XL4DLL\Common\p1.lib" /LTCG /MACHINE:X86 /SUBSYSTEM:WINDOWS /NOLOGO
Checked with dumpbin.exe as suggested, and the symbol "?runLocal##YGHXZ" exists in p1.lib
P2 compiler options:
/permissive- /MP /GS /TP /GL /analyze- /W3 /Gy /Zc:wchar_t
/I"C:\_tools\boost_1_68_0\" /I"C:\_tools\cryptopp_8_2_0\"
/Qspectre /guard:cf /Zi /Gm- /O2 /sdl /Fd"tmp_Win32_Release\vc142.pdb"
/Zc:inline /fp:precise /D "WIN32" /D "NDEBUG" /D "_WINDOWS" /D "_USRDLL"
/D "_WINDLL" /D "_UNICODE" /D "UNICODE"
/errorReport:prompt /WX- /Zc:forScope /Gz /Oy /Oi /MD /std:c++17 /FC
/Fa"tmp_Win32_Release\" /EHsc /nologo /Fo"tmp_Win32_Release\" /Ot
/Fp"tmp_Win32_Release\XL4DLL32.pch" /diagnostics:column
P2 linker options:
/OUT:"D:\Projets\XL4DLL\Release\XL4DLL32.dll" /MANIFEST /LTCG:incremental
/NXCOMPAT /PDB:"D:\Projets\XL4DLL\Release\XL4DLL32.pdb" /DYNAMICBASE
"D:\Projets\XL4DLL\Common\p1.lib" "D:\Projets\XL4DLL\Common\SharedToolsLib32.lib"
"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:"D:\Projets\XL4DLL\Release\XL4DLL32.lib" /DLL /MACHINE:X86
/OPT:REF /SAFESEH /INCREMENTAL:NO /PGD:"D:\Projets\XL4DLL\Release\XL4DLL32.pgd"
/SUBSYSTEM:WINDOWS /MANIFESTUAC:"level='asInvoker' uiAccess='false'"
/ManifestFile:"tmp_Win32_Release\XL4DLL32.dll.intermediate.manifest"
/OPT:ICF /ERRORREPORT:PROMPT /NOLOGO
/LIBPATH:"C:\_tools\boost_1_68_0\stage\lib" /TLBID:1
There is another difference between P1 and P2 projects configuration:
P1 is configured to use "Use MFC in a Shared DLL"
P2 is configured to use "Use Standard Windows Libraries", because it requires the use of Windows.h header and uses symbols not defined with MFC usage.