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Re: [PATCH] trigraphs


On 21-Jul-2003, Matt Austern <austern@apple.com> wrote:
> On Monday, July 21, 2003, at 12:01PM, Jason Merrill wrote:
> I agree that turning off the warning unconditionally is a bad idea.  The real
> question is whether the warning should be turned on by -Wall or only if the
> user explicitly uses -Wtrigraphs.
> 
> I claim that the latter makes more sense.  -Wall is supposed to be a
> collection of warnings that are appropriate for most users: the idea is
> that, in general, "good" code should compile clean under -Wall.
>
> This doesn't apply to -Wtrigraphs.  The vast majority of users have no reason
> to care about trigraphs.  They are never going to use the -trigraphs 
> flag and have no reason to care what would happen in -trigraphs mode.

These users (or their colleagues) may well attempt to compile their
code with some other C compiler which has trigraphs enabled by default.
If they do so, the code may suddenly change in meaning, resulting in
a portability problem.

Constructs which are likely to cause portability problems (and which are
easy to avoid) should be warned about with -Wall.  So I think -Wtrigraphs
should be part of -Wall.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.


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