I've really been banging my head against the proverbial wall over this one.
I have a solution which contains both C# and C++ code projects.
I often call the C++ DLLs, which are compiled in this project from the C# via P/Invoke. No problemo. All the requisite debugger settings through the *.sln file, as well as the C++ and C# files, have been properly set, to the best of my knowledge. Note: I often am able to debug similarly P/Invoked C++ code with no issues!
Naturally, I figured that, perhaps, the symbols weren't loading -- yet, upon opening the modules window, I discovered that the DLL into which I am attempting to step isn't even listed! Running the function in my C# program does indeed use the DLL(I get the correct output), but, whilst watching the Modules window, the DLL still does not appear.
Does anyone have an idea of what's going on?
tl;dr
I have a fair amount of experience with debugging P/Invoked C++. However, the DLL I wish to debug does not even appear in the Modules list(so I obviously am not able to step into it if the VS debugger appears to be completely unaware of its existence).
My guess would be that you do not have debugging turned on for unmanaged code. Go to the Start-up project's Properties->Debug tab. Check "Enable unmanaged code debugging".
来源：https://stackoverflow.com/questions/15234384/dll-missing-from-modules-list-in-vs2010