From: utzoo!decvax!cca!dan@BBN-UNIX@sri-unix
Newsgroups: net.unix-wizards
Title: Re: Comments in C
Article-I.D.: sri-unix.4367
Posted: Wed Nov 24 02:19:42 1982
Received: Thu Nov 25 12:17:36 1982

From: Dan Franklin <dan at BBN-UNIX>
Date: 23 Nov 1982  0:47:28 EST (Tuesday)
I think the subject's been just about beaten to death, but: yes, whether
comments nest or not, a friendly compiler can point out a problem ('unterminated
comment at line #' or 'comment within comment at line #'), and an unfriendly
compiler can be equally useless either way.  I do not believe that if comments
nested, cc would necessarily diagnose errors for you; as evidence I submit the
fact that although #if and #endif nest, if you forget an #endif the V7
preprocessor gives you the "silent treatment" that UNIX is so justly famed for.
(It is also slightly more difficult to handle nested comments correctly, since
you have to keep a stack of starting comment line numbers, but of course anyone
who sets out to write a compiler shouldn't find that particularly daunting!)

If anyone is seriously thinking of changing the compiler, I really think that
changing it to warn about comments within comments, rather than changing it to
make comments nest, is more appropriate--compatibility being a lot more
important than immediate convenience.  But the right place to put such a check
is probably in lint, given the current situation.

    Dan