what does it mean? Require source files to exactly match the original version

Situation: You have loaded in your editor a version of a file which is different than the one compiled into the executable you are debugging.

If the option is selected, and you try to debug code in that file, you will be prompted to find the right one, or else you will not be able to step into or break on any of that file's functions. (I think the pop-up dialog also allows you to select "use this version anyway").

If the option is not selected, you will see your version of the file. However, the code you see may be very different from the code that is executing. The breakpoint will be displayed on the line number matching the old file. It may show up in a blank line, or a comment, or some other function entirely.

In general, you should select it, so that you know that what you are seeing is what you are running.

I would leave the option selected.

Consider the following situation:

• Build some code
• Make a change to a source file
• Start debugging

Now when you are debugging, the source file no longer matches what was used during compilation. This might leave you with breakpoints or line numbers that no longer match what's actually happening in the debugger.

If there is some reason why you want to see your local code instead, deselect the option.