Re: backslash whitespace newline

[Joe Buck <Joe dot Buck at synopsys dot COM>]

On Tue, Oct 25, 2005 at 08:22:12PM -0400, Andrew Pinski wrote:
> Why not get other compilers to change to what GCC does?  Why does GCC
> have to follow what other compilers do, maybe other compilers 
> would be in the best interest of following what GCC does.

The problem, I think, is that the behavior of both GCC *and* the
other compilers does not serve the users.

The reason is that there simply isn't any reason why a user would
use a backslash to continue a C++ comment on purpose, and plenty of
reason why she might do it by accident.

There appear to be five relevant cases; the backslash-newline (or
whitespace/backslash/newline) can be in

1) a C++ comment
2) a C comment
3) a string literal
4) a preprocessor directive
5) somewhere else.

For cases 2 and 5, the behavior doesn't matter.  For case 3, the
continuation is unlikely to be accidental, and the user is, I think,
less likely to leave a stray slash in case 4.

But case 1 is the nasty one, as users think they can put anything
in a comment.  A backslash at the end is likely to be an accident,
since just starting the next line with a // is easy enough.

So, I think that a trailing backslash at the end of a C++ comment
(followed or not by whitespace) should be warned about.  I think
Apple's customers would want this warning too, since many of them
will also be interested in compiling for other systems, and there
is a lot of gcc 3.x out there.  Best to use warnings to get rid
of the problematic code.