Why doesn't Edit & Continue work for me in VS2008 with a legacy C++ win32 project?

Question

If I create a new win32 C++ project in VS2008 I can use Edit & Continue with it just fine, but with this legacy project I'm working with my attempts to use / enable it have failed.

Here are things I've checked:

Tools -> Options -> Debugging -> Edit and Continue -> Enable Edit and Continue is ON.

Debug Information Format: Program Database (/Zi)

Code Generation -> Enable Function-Level Linking: Yes (/Gy)

Looked for a corrupt .ILK file. I can't find any .ILK files - are they still used in 2008?

But when I step into the program, change the next line, and step again, I get:

"This source file has changed. It no longer matches..."

rather than

"Would you like Edit & Continue to apply your code changes."

What's wrong with this project that E&C doesn't work?

Answer 1

I assume you have debugging symbols/etc and the legacy C++ application had been compiled with this support...

If not, then you will run into the problem that the code was not 'instrumented' to allow for injection of alternate code.

I would suspect that the changes in output code format would make VC++ 2008 incompatible... as I doubt Microsoft added such backwards compatibility in (until VS 2008, I think they even made it hard to use older versions of .Net without using the specific VS)