Path: utzoo!attcan!uunet!husc6!rutgers!att!ulysses!andante!alice!ark
From: ark@alice.UUCP (Andrew Koenig)
Newsgroups: comp.unix.wizards
Subject: Re: diff
Message-ID: <8702@alice.UUCP>
Date: 7 Jan 89 17:13:42 GMT
References: <5174@lynx.UUCP>
Distribution: na
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 41

In article <5174@lynx.UUCP>, m5@lynx.uucp (Mike McNally) writes:
> While hacking on GNU diff to add the -D option, I noticed a seemingly
> unavoidable problem with the whole concept.  The -D option generates

There's another problem:

	File 1:

	stuff 1
	#ifdef X
	stuff 2
	#endif
	stuff 3


	File 2:

	stuff 1
	#ifdef Y
	stuff 2
	#endif
	stuff 3

The obvious way to merge this is:

	stuff 1
	#ifdef FOO
	#ifdef X
	#else
	#ifdef Y
	#endif
	stuff 2
	#endif
	stuff 3

but this is obviously wrong.

The correct solution is left as an exercise for the reader.
-- 
				--Andrew Koenig
				  ark@europa.att.com