Question

I’ve just came up with an idea to solve a problem and wanted to share it. Sorry if too banal.

So, a big C++ project I am reviewing, contains many includes which relies on symbols from other includes but which don’t include the required includes. Any slight change in build-procedure results in “missing symbol” failures.

So in order to check all includes for self-containment at once, I search for all *.h, create on the fly a cpp-file which only contains #include -statement with this .h file and try to compile it. At the end I obtain a list of “good” and “bad” include files.
Cool isn’t it 🙂
Or is there an easier solution to do it?

Answer 1

If every .cpp file includes it’s own header-file first, and then other headers, you’ll get this check without using external tools.

This is actually part of Googles C++ Style Guide for the same reason:

The preferred ordering reduces hidden
dependencies. We want every header
file to be compilable on its own. The
easiest way to achieve this is to make
sure that every one of them is the
first .h file #included in some .cc.

If you have any header files that does not have a corresponding .cpp-file, you’d have to do something special for them.