IAR C Preprocessor include directories - iar

Question

I've been asked to make a small mod to some software that was written back in the mid naughties on IAR Embedded Workbench v3.3
I have had the original source files copied from an old machine to one I have been given for the task.
For the moment I am simply trying to get the software compiling. It took me a while to realise, or at least I thought I'd realised, that the reason it couldn't open various header files was that, incredibly, all the include paths were absolute, not relative.
So, I changed all the paths to be $PROJ_DIR$ relative, but then started to get different files that couldn't be opened. Then realised that the machine they gave me just happened to have a very similar directory structure to the original machine used and, amazingly, had quite a few of the same files in the directory structure of this machine I'm using as was on the machine used to compile the code originally.
I then thought, OK, I'll just check I have got my relative paths correct by choosing one of the header files it was complaining about not finding and putting, in the Preprocessor tab, an absolute path to the directory on this machine I'm using that contained the header file it wanted. However, that still wouldn't find the header file!
Finally, I put an absolute path in the c file to point to the desired header file.
#include "C:\absolute__Path\stdtyp.h"
And it compiled.
To confirm:
Putting C:\absolute__Path
in the Project | Options | C/C++ compiler | Preprocessor tab will not work if I just have:
#include "stdtyp.h"
in the c file.
I have used IAR in the past - not that much - but I have used it and I was sure that's where you set your include directories. So, am I wrong, or can there be something else that is overriding that path in the Preprocessor tab as described above?
Edit: I'm not wrong, after having slept on it, I decided to create a new project with random directories, subdirectories and header files. Sure enough, if I set and remove $PROJ_DIR$ referenced paths in the preprocessor tab, the new project compiles, then doesn't. So, there must be something, presumably in the ewp file that is borking it.

Answer 1

It turns out you can override the paths on an individual file by file basis. So, the rogue files had the paths overridden and had absolute paths.
Right click on the file in EW and select Options.
That then for most file shows a load of greyed out boxes. What I'd failed to do was thoroughly check all files. The few I'd randomly checked were greyed out, but some files had their properties overridden here with different (and absolute) paths put there.
At least now the project can be easily copied between machines having used relative paths.