please keep the "deprecated" -I- option: it has important functionality not available elsewhere

please keep the "deprecated" -I- option: it has important functionality not available elsewhere

[Mark Galeck (CW)]

Hello,

I am the author of Foundry build system which is now transitioning to the use of gcc from another compiler.  This is great because gcc is an excellent compiler.  However. there is a potential problem for me.

I hope that the designers of gcc are aware, that some of the gcc (as any advanced software tool) options, are for "convenience", while some are for "uniformity".

With a small system, like, a few files to compile, convenience is the key - you want to write the necessary commands to do your compilation, as quickly as possible. 

With a huge system of hundreds of thousands of files, convenience goes out the window, and the important thing is instead, uniformity. The useful features are the ones who behave in a simple way and always in the same way.  That is the only way, with such a large system, for a human to get a handle on the behaviour of the system.

Case in point, is the use of "current directory" for -I/-iquote include file searches.  That the "current directory" (the directory that the currently preprocessed file was found) is searched first, is a "convenience" feature.  For a system with few files, it is very useful.  For a huge system, with gazillions of files with duplicate names all over, in order to be sure that the intended include files are included and not some other duplicates, it is crucial to have a simple, uniform algorithm for the search, which lends itself easily to script automation.  

The addition of "current directory" to the search algorithm, makes it in practice impossible to ensure always the correct files are included (in a huge system).  

That is why I always disabled the "current directory" (and also disabled the use of "system" directories, and disabled any difference between "" and <>). That way, the one and only thing to worry about is the ordering of -I directories. 

As I can see, the only way to get this effect in gcc, is with -I- put before all the -I options.  In fact, -I- option is really for something else, and this disabling of current directory is a side effect.  The whole option is obsolete, and the side effect is in fact thought of as a nuisance in the manual.  

Nothing could be more misguided!  This "strange side effect" is in fact very important.  


So please don't remove -I- (or make it possible to disable the current directory search, with some other option).  


Thank you,

Mark Galeck